[Title 40 CFR ]
[Code of Federal Regulations (annual edition) - July 1, 2000 Edition]
[From the U.S. Government Printing Office]



[[Page i]]

          

                    40


          Parts 50 to 51

                         Revised as of July 1, 2000

Protection of Environment





          Containing a Codification of documents of general 
          applicability and future effect
          As of July 1, 2000
          With Ancillaries
          Published by
          Office of the Federal Register
          National Archives and Records
          Administration

As a Special Edition of the Federal Register



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                     U.S. GOVERNMENT PRINTING OFFICE
                            WASHINGTON : 2000



               For sale by U.S. Government Printing Office
 Superintendent of Documents, Mail Stop: SSOP, Washington, DC 20402-9328



[[Page iii]]




                            Table of Contents



                                                                    Page
  Explanation.................................................       v

  Title 40:
          Chapter I--Environmental Protection Agency                 3
  Finding Aids:
      Material Incorporated by Reference......................     485
      Table of CFR Titles and Chapters........................     487
      Alphabetical List of Agencies Appearing in the CFR......     505
      List of CFR Sections Affected...........................     515



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                     ----------------------------

                     Cite this Code:  CFR
                     To cite the regulations in 
                       this volume use title, 
                       part and section number. 
                       Thus,  40 CFR 50.1 refers 
                       to title 40, part 50, 
                       section 1.

                     ----------------------------

[[Page v]]



                               EXPLANATION

    The Code of Federal Regulations is a codification of the general and 
permanent rules published in the Federal Register by the Executive 
departments and agencies of the Federal Government. The Code is divided 
into 50 titles which represent broad areas subject to Federal 
regulation. Each title is divided into chapters which usually bear the 
name of the issuing agency. Each chapter is further subdivided into 
parts covering specific regulatory areas.
    Each volume of the Code is revised at least once each calendar year 
and issued on a quarterly basis approximately as follows:

Title 1 through Title 16.................................as of January 1
Title 17 through Title 27..................................as of April 1
Title 28 through Title 41...................................as of July 1
Title 42 through Title 50................................as of October 1

    The appropriate revision date is printed on the cover of each 
volume.

LEGAL STATUS

    The contents of the Federal Register are required to be judicially 
noticed (44 U.S.C. 1507). The Code of Federal Regulations is prima facie 
evidence of the text of the original documents (44 U.S.C. 1510).

HOW TO USE THE CODE OF FEDERAL REGULATIONS

    The Code of Federal Regulations is kept up to date by the individual 
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    To determine whether a Code volume has been amended since its 
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the daily Federal Register. These two lists will identify the Federal 
Register page number of the latest amendment of any given rule.

EFFECTIVE AND EXPIRATION DATES

    Each volume of the Code contains amendments published in the Federal 
Register since the last revision of that volume of the Code. Source 
citations for the regulations are referred to by volume number and page 
number of the Federal Register and date of publication. Publication 
dates and effective dates are usually not the same and care must be 
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Code a note has been inserted to reflect the future effective date. In 
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inserted following the text.

OMB CONTROL NUMBERS

    The Paperwork Reduction Act of 1980 (Pub. L. 96-511) requires 
Federal agencies to display an OMB control number with their information 
collection request.

[[Page vi]]

Many agencies have begun publishing numerous OMB control numbers as 
amendments to existing regulations in the CFR. These OMB numbers are 
placed as close as possible to the applicable recordkeeping or reporting 
requirements.

OBSOLETE PROVISIONS

    Provisions that become obsolete before the revision date stated on 
the cover of each volume are not carried. Code users may find the text 
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1963, 1964-1972, or 1973-1985, published in seven separate volumes. For 
the period beginning January 1, 1986, a ``List of CFR Sections 
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INCORPORATION BY REFERENCE

    What is incorporation by reference? Incorporation by reference was 
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to materials already published elsewhere. For an incorporation to be 
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This material, like any other properly issued regulation, has the force 
of law.
    What is a proper incorporation by reference? The Director of the 
Federal Register will approve an incorporation by reference only when 
the requirements of 1 CFR part 51 are met. Some of the elements on which 
approval is based are:
    (a) The incorporation will substantially reduce the volume of 
material published in the Federal Register.
    (b) The matter incorporated is in fact available to the extent 
necessary to afford fairness and uniformity in the administrative 
process.
    (c) The incorporating document is drafted and submitted for 
publication in accordance with 1 CFR part 51.
    Properly approved incorporations by reference in this volume are 
listed in the Finding Aids at the end of this volume.
    What if the material incorporated by reference cannot be found? If 
you have any problem locating or obtaining a copy of material listed in 
the Finding Aids of this volume as an approved incorporation by 
reference, please contact the agency that issued the regulation 
containing that incorporation. If, after contacting the agency, you find 
the material is not available, please notify the Director of the Federal 
Register, National Archives and Records Administration, Washington DC 
20408, or call (202) 523-4534.

CFR INDEXES AND TABULAR GUIDES

    A subject index to the Code of Federal Regulations is contained in a 
separate volume, revised annually as of January 1, entitled CFR Index 
and Finding Aids. This volume contains the Parallel Table of Statutory 
Authorities and Agency Rules (Table I). A list of CFR titles, chapters, 
and parts and an alphabetical list of agencies publishing in the CFR are 
also included in this volume.
    An index to the text of ``Title 3--The President'' is carried within 
that volume.
    The Federal Register Index is issued monthly in cumulative form. 
This index is based on a consolidation of the ``Contents'' entries in 
the daily Federal Register.
    A List of CFR Sections Affected (LSA) is published monthly, keyed to 
the revision dates of the 50 CFR titles.

[[Page vii]]


REPUBLICATION OF MATERIAL

    There are no restrictions on the republication of material appearing 
in the Code of Federal Regulations.

INQUIRIES

    For a legal interpretation or explanation of any regulation in this 
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    For inquiries concerning CFR reference assistance, call 202-523-5227 
or write to the Director, Office of the Federal Register, National 
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SALES

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                              Raymond A. Mosley,
                                    Director,
                          Office of the Federal Register.

July 1, 2000.



[[Page ix]]



                               THIS TITLE

    Title 40--Protection of Environment is composed of twenty-four 
volumes. The parts in these volumes are arranged in the following order: 
parts 1-49, parts 50-51, part 52 (52.01-52.1018), part 52 (52.1019-End), 
parts 53-59, part 60, parts 61-62, part 63 (63.1-63.1199), part 63 
(63.1200-End), parts 64-71, parts 72-80, parts 81-85, part 86, parts 87-
135, parts 136-149, parts 150-189, parts 190-259, parts 260-265, parts 
266-299, parts 300-399, parts 400-424, parts 425-699, parts 700-789, and 
part 790 to End. The contents of these volumes represent all current 
regulations codified under this title of the CFR as of July 1, 2000.

    Chapter I--Environmental Protection Agency appears in all twenty-
four volumes. A Pesticide Tolerance Commodity/Chemical Index and Crop 
Grouping Commodities Index appear in parts 150-189. A Toxic Substances 
Chemical--CAS Number Index appears in parts 700-789 and part 790 to End. 
Redesignation Tables appear in the volumes containing parts 50-51, parts 
150-189, and parts 700-789. Regulations issued by the Council on 
Environmental Quality appear in the volume containing part 790 to End. 
The OMB control numbers for title 40 appear in Sec. 9.1 of this chapter.

    For this volume, Kenneth R. Payne was Chief Editor. The Code of 
Federal Regulations publication program is under the direction of 
Frances D. McDonald, assisted by Alomha S. Morris.

[[Page x]]





[[Page 1]]



                   TITLE 40--PROTECTION OF ENVIRONMENT




                   (This book contains parts 50 to 51)

  --------------------------------------------------------------------
                                                                    Part

chapter i--Environmental Protection Agency (Continued)......          50

[[Page 3]]



               CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY




  --------------------------------------------------------------------


  Editorial Note: Subchapter C--Air Programs is continued in volumes 40 
CFR parts 50-51, part 52 (52.01-52.1018), part 52 (52.1019-End), parts 
53-59, part 60, parts 61-62, part 63 (63.1-63.1199), part 63 (63.1200-
End), parts 64-71, parts 72-80, parts 81-85, part 86, and parts 87-135.

                       SUBCHAPTER C--AIR PROGRAMS

Part                                                                Page
50              National primary and secondary ambient air 
                    quality standards.......................           5
51              Requirements for preparation, adoption, and 
                    submittal of implementation plans.......         129

[[Page 5]]





                       SUBCHAPTER C--AIR PROGRAMS



PART 50--NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS--Table of Contents




Sec.
50.1  Definitions.
50.2  Scope.
50.3  Reference conditions.
50.4  National primary ambient air quality standards for sulfur oxides 
          (sulfur dioxide).
50.5  National secondary ambient air quality standard for sulfur oxides 
          (sulfur dioxide).
50.6  National primary and secondary ambient air quality standards for 
          PM10.
50.7  National primary and secondary ambient air quality standards for 
          particulate matter.
50.8  National primary ambient air quality standards for carbon 
          monoxide.
50.9  National 1-hour primary and secondary ambient air quality 
          standards for ozone.
50.10  National 8-hour primary and secondary ambient air quality 
          standards for ozone.
50.11  National primary and secondary ambient air quality standards for 
          nitrogen dioxide.
50.12  National primary and secondary ambient air quality standards for 
          lead.

Appendix A to Part 50--Reference Method for the Determination of Sulfur 
          Dioxide in the Atmosphere (Pararosaniline Method)
Appendix B to Part 50--Reference Method for the Determination of 
          Suspended Particulate Matter in the Atmosphere (High-Volume 
          Method)
Appendix C to Part 50--Measurement Principle and Calibration Procedure 
          for the Measurement of Carbon Monoxide in the Atmosphere (Non-
          Dispersive Infrared Photometry)
Appendix D to Part 50--Measurement Principle and Calibration Procedure 
          for the Measurement of Ozone in the Atmosphere
Appendix E to Part 50 [Reserved]
Appendix F to Part 50--Measurement Principle and Calibration Procedure 
          for the Measurement of Nitrogen Dioxide in the Atmosphere (Gas 
          Phase Chemiluminescence)
Appendix G to Part 50--Reference Method for the Determination of Lead in 
          Suspended Particulate Matter Collected From Ambient Air
Appendix H to Part 50--Interpretation of the 1-Hour Primary and 
          Secondary National Ambient Air Quality Standards for Ozone
Appendix I to Part 50--Interpretation of the 8-Hour Primary and 
          Secondary National Ambient Air Quality Standards for Ozone
Appendix J to Part 50--Reference Method for the Determination of 
          Particulate Matter as PM10 in the Atmosphere
Appendix K to Part 50--Interpretation of the National Ambient Air 
          Quality Standards for Particulate Matter
Appendix L to Part 50--Reference Method for the Determination of Fine 
          Particulate Matter as PM2.5 in the Atmosphere
Appendix M to Part 50--Reference Method for the Determination of 
          Particulate Matter as PM10 in the Atmosphere
Appendix N to Part 50--Interpretation of the National Ambient Air 
          Quality Standards for Particulate Matter

    Authority: 42 U.S.C. 7401, et seq.

    Source: 36 FR 22384, Nov. 25, 1971, unless otherwise noted.



Sec. 50.1  Definitions.

    (a) As used in this part, all terms not defined herein shall have 
the meaning given them by the Act.
    (b) Act means the Clean Air Act, as amended (42 U.S.C. 1857-18571, 
as amended by Pub. L. 91-604).
    (c) Agency means the Environmental Protection Agency.
    (d) Administrator means the Administrator of the Environmental 
Protection Agency.
    (e) Ambient air means that portion of the atmosphere, external to 
buildings, to which the general public has access.
    (f) Reference method means a method of sampling and analyzing the 
ambient air for an air pollutant that is specified as a reference method 
in an appendix to this part, or a method that has been designated as a 
reference method in accordance with part 53 of this chapter; it does not 
include a method for which a reference method designation has been 
cancelled in accordance with Sec. 53.11 or Sec. 53.16 of this chapter.
    (g) Equivalent method means a method of sampling and analyzing the 
ambient air for an air pollutant that has been designated as an 
equivalent method in accordance with part 53 of this chapter; it does 
not include a method for which an equivalent method designation has

[[Page 6]]

been cancelled in accordance with Sec. 53.11 or Sec. 53.16 of this 
chapter.
    (h) Traceable means that a local standard has been compared and 
certified either directly or via not more than one intermediate 
standard, to a primary standard such as a National Bureau of Standards 
Standard Reference Material (NBS SRM), or a USEPA/NBS-approved Certified 
Reference Material (CRM).
    (i) Indian country is as defined in 18 U.S.C. 1151.

[36 FR 22384, Nov. 25, 1971, as amended at 41 FR 11253, Mar. 17, 1976; 
48 FR 2529, Jan. 20, 1983; 63 FR 7274, Feb. 12, 1998]



Sec. 50.2  Scope.

    (a) National primary and secondary ambient air quality standards 
under section 109 of the Act are set forth in this part.
    (b) National primary ambient air quality standards define levels of 
air quality which the Administrator judges are necessary, with an 
adequate margin of safety, to protect the public health. National 
secondary ambient air quality standards define levels of air quality 
which the Administrator judges necessary to protect the public welfare 
from any known or anticipated adverse effects of a pollutant. Such 
standards are subject to revision, and additional primary and secondary 
standards may be promulgated as the Administrator deems necessary to 
protect the public health and welfare.
    (c) The promulgation of national primary and secondary ambient air 
quality standards shall not be considered in any manner to allow 
significant deterioration of existing air quality in any portion of any 
State or Indian country.
    (d) The proposal, promulgation, or revision of national primary and 
secondary ambient air quality standards shall not prohibit any State or 
Indian country from establishing ambient air quality standards for that 
State or area under a tribal CAA program or any portion thereof which 
are more stringent than the national standards.

[36 FR 22384, Nov. 25, 1971, as amended at 63 FR 7274, Feb. 12, 1998]



Sec. 50.3   Reference conditions.

    All measurements of air quality that are expressed as mass per unit 
volume (e.g., micrograms per cubic meter) other than for the particulate 
matter (PM10 and PM2.5) standards contained in 
Sec. 50.7 shall be corrected to a reference temperature of 25  deg.C and 
a reference pressure of 760 millimeters of mercury (1,013.2 millibars). 
Measurements of PM10 and PM2.5 for purposes of 
comparison to the standards contained in Sec. 50.7 shall be reported 
based on actual ambient air volume measured at the actual ambient 
temperature and pressure at the monitoring site during the measurement 
period.

[62 FR 38711, July 18, 1997]



Sec. 50.4  National primary ambient air quality standards for sulfur oxides (sulfur dioxide).

    (a) The level of the annual standard is 0.030 parts per million 
(ppm), not to be exceeded in a calendar year. The annual arithmetic mean 
shall be rounded to three decimal places (fractional parts equal to or 
greater than 0.0005 ppm shall be rounded up).
    (b) The level of the 24-hour standard is 0.14 parts per million 
(ppm), not to be exceeded more than once per calendar year. The 24-hour 
averages shall be determined from successive nonoverlapping 24-hour 
blocks starting at midnight each calendar day and shall be rounded to 
two decimal places (fractional parts equal to or greater than 0.005 ppm 
shall be rounded up).
    (c) Sulfur oxides shall be measured in the ambient air as sulfur 
dioxide by the reference method described in appendix A to this part or 
by an equivalent method designated in accordance with part 53 of this 
chapter.
    (d) To demonstrate attainment, the annual arithmetic mean and the 
second-highest 24-hour averages must be based upon hourly data that are 
at least 75 percent complete in each calendar quarter. A 24-hour block 
average shall be considered valid if at least 75 percent of the hourly 
averages for the 24-hour period are available. In the event that only 
18, 19, 20, 21, 22, or 23 hourly averages are available, the 24-hour 
block average shall be computed as the sum of the available hourly

[[Page 7]]

averages using 18, 19, etc. as the divisor. If fewer than 18 hourly 
averages are available, but the 24-hour average would exceed the level 
of the standard when zeros are substituted for the missing values, 
subject to the rounding rule of paragraph (b) of this section, then this 
shall be considered a valid 24-hour average. In this case, the 24-hour 
block average shall be computed as the sum of the available hourly 
averages divided by 24.

[61 FR 25579, May 22, 1996]



Sec. 50.5  National secondary ambient air quality standard for sulfur oxides (sulfur dioxide).

    (a) The level of the 3-hour standard is 0.5 parts per million (ppm), 
not to be exceeded more than once per calendar year. The 3-hour averages 
shall be determined from successive nonoverlapping 3-hour blocks 
starting at midnight each calendar day and shall be rounded to 1 decimal 
place (fractional parts equal to or greater than 0.05 ppm shall be 
rounded up).
    (b) Sulfur oxides shall be measured in the ambient air as sulfur 
dioxide by the reference method described in appendix A of this part or 
by an equivalent method designated in accordance with part 53 of this 
chapter.
    (c) To demonstrate attainment, the second-highest 3-hour average 
must be based upon hourly data that are at least 75 percent complete in 
each calendar quarter. A 3-hour block average shall be considered valid 
only if all three hourly averages for the 3-hour period are available. 
If only one or two hourly averages are available, but the 3-hour average 
would exceed the level of the standard when zeros are substituted for 
the missing values, subject to the rounding rule of paragraph (a) of 
this section, then this shall be considered a valid 3-hour average. In 
all cases, the 3-hour block average shall be computed as the sum of the 
hourly averages divided by 3.

[61 FR 25580, May 22, 1996]



Sec. 50.6   National primary and secondary ambient air quality standards for PM10.

    (a) The level of the national primary and secondary 24-hour ambient 
air quality standards for particulate matter is 150 micrograms per cubic 
meter (g/m\3\), 24-hour average concentration. The standards 
are attained when the expected number of days per calendar year with a 
24-hour average concentration above 150 g/m\3\, as determined 
in accordance with appendix K to this part, is equal to or less than 
one.
    (b) The level of the national primary and secondary annual standards 
for particulate matter is 50 micrograms per cubic meter (g/
m\3\), annual arithmetic mean. The standards are attained when the 
expected annual arithmetic mean concentration, as determined in 
accordance with appendix K to this part, is less than or equal to 50 
g/m\3\.
    (c) For the purpose of determining attainment of the primary and 
secondary standards, particulate matter shall be measured in the ambient 
air as PM10 (particles with an aerodynamic diameter less than 
or equal to a nominal 10 micrometers) by:
    (1) A reference method based on appendix J and designated in 
accordance with part 53 of this chapter, or
    (2) An equivalent method designated in accordance with part 53 of 
this chapter.
    (d) The PM10 standards set forth in this section will no 
longer apply to an area not attaining these standards as of September 
16, 1997, once EPA takes final action to promulgate a rule pursuant to 
section 172(e) of the Clean Air Act, as amended (42 U.S.C. 7472(e)) 
applicable to the area. The PM10 standards set forth in this 
section will no longer apply to an area attaining these standards as of 
September 16, 1997, once EPA approves a State Implementation Plan (SIP) 
applicable to the area containing all PM10 control measures 
adopted and implemented by the State prior to September 16, 1997, and a 
section 110 SIP implementing the PM standards published on July 18, 
1997.

[[Page 8]]

SIP approvals are codified in 40 CFR part 52.

[52 FR 24663, July 1, 1987, as amended at 62 FR 38711, July 18, 1997]



Sec. 50.7   National primary and secondary ambient air quality standards for particulate matter.

    (a) The national primary and secondary ambient air quality standards 
for particulate matter are:
    (1) 15.0 micrograms per cubic meter (g/m3) 
annual arithmetic mean concentration, and 65 g/m3 
24-hour average concentration measured in the ambient air as 
PM2.5 (particles with an aerodynamic diameter less than or 
equal to a nominal 2.5 micrometers) by either:
    (i) A reference method based on appendix L of this part and 
designated in accordance with part 53 of this chapter; or
    (ii) An equivalent method designated in accordance with part 53 of 
this chapter.
    (2) 50 micrograms per cubic meter (g/m3) annual 
arithmetic mean concentration, and 150 g/m3 24-hour 
average concentration measured in the ambient air as PM10 
(particles with an aerodynamic diameter less than or equal to a nominal 
10 micrometers) by either:
    (i) A reference method based on appendix M of this part and 
designated in accordance with part 53 of this chapter; or
    (ii) An equivalent method designated in accordance with part 53 of 
this chapter.
    (b) The annual primary and secondary PM2.5 standards are 
met when the annual arithmetic mean concentration, as determined in 
accordance with appendix N of this part, is less than or equal to 15.0 
micrograms per cubic meter.
    (c) The 24-hour primary and secondary PM2.5 standards are 
met when the 98th percentile 24-hour concentration, as 
determined in accordance with appendix N of this part, is less than or 
equal to 65 micrograms per cubic meter.
    (d) The annual primary and secondary PM10 standards are 
met when the annual arithmetic mean concentration, as determined in 
accordance with appendix N of this part, is less than or equal to 50 
micrograms per cubic meter.
    (e) The 24-hour primary and secondary PM10 standards are 
met when the 99th percentile 24-hour concentration, as 
determined in accordance with appendix N of this part, is less than or 
equal to 150 micrograms per cubic meter.

[62 FR 38711, July 18, 1997]



Sec. 50.8  National primary ambient air quality standards for carbon monoxide.

    (a) The national primary ambient air quality standards for carbon 
monoxide are:
    (1) 9 parts per million (10 milligrams per cubic meter) for an 8-
hour average concentration not to be exceeded more than once per year 
and
    (2) 35 parts per million (40 milligrams per cubic meter) for a 1-
hour average concentration not to be exceeded more than once per year.
    (b) The levels of carbon monoxide in the ambient air shall be 
measured by:
    (1) A reference method based on appendix C and designated in 
accordance with part 53 of this chapter, or
    (2) An equivalent method designated in accordance with part 53 of 
this chapter.
    (c) An 8-hour average shall be considered valid if at least 75 
percent of the hourly average for the 8-hour period are available. In 
the event that only six (or seven) hourly averages are available, the 8-
hour average shall be computed on the basis of the hours available using 
six (or seven) as the divisor.
    (d) When summarizing data for comparision with the standards, 
averages shall be stated to one decimal place. Comparison of the data 
with the levels of the standards in parts per million shall be made in 
terms of integers with fractional parts of 0.5 or greater rounding up.

[50 FR 37501, Sept. 13, 1985]



Sec. 50.9   National 1-hour primary and secondary ambient air quality standards for ozone.

    (a) The level of the national 1-hour primary and secondary ambient 
air quality standards for ozone measured

[[Page 9]]

by a reference method based on appendix D to this part and designated in 
accordance with part 53 of this chapter, is 0.12 parts per million (235 
g/m3). The standard is attained when the expected 
number of days per calendar year with maximum hourly average 
concentrations above 0.12 parts per million (235 g/
m3) is equal to or less than 1, as determined by appendix H 
to this part.
    (b) The 1-hour standards set forth in this section will no longer 
apply to an area once EPA determines that the area has air quality 
meeting the 1-hour standard. Area designations are codified in 40 CFR 
part 81.

[62 FR 38894, July 18, 1997]



Sec. 50.10   National 8-hour primary and secondary ambient air quality standards for ozone.

    (a) The level of the national 8-hour primary and secondary ambient 
air quality standards for ozone, measured by a reference method based on 
appendix D to this part and designated in accordance with part 53 of 
this chapter, is 0.08 parts per million (ppm), daily maximum 8-hour 
average.
    (b) The 8-hour primary and secondary ozone ambient air quality 
standards are met at an ambient air quality monitoring site when the 
average of the annual fourth-highest daily maximum 8-hour average ozone 
concentration is less than or equal to 0.08 ppm, as determined in 
accordance with appendix I to this part.

[62 FR 38894, July 18, 1997]



Sec. 50.11  National primary and secondary ambient air quality standards for nitrogen dioxide.

    (a) The level of the national primary ambient air quality standard 
for nitrogen dioxide is 0.053 parts per million (100 micrograms per 
cubic meter), annual arithmetic mean concentration.
    (b) The level of national secondary ambient air quality standard for 
nitrogen dioxide is 0.053 parts per million (100 micrograms per cubic 
meter), annual arithmetic mean concentration.
    (c) The levels of the standards shall be measured by:
    (1) A reference method based on appendix F and designated in 
accordance with part 53 of this chapter, or
    (2) An equivalent method designated in accordance with part 53 of 
this chapter.
    (d) The standards are attained when the annual arithmetic mean 
concentration in a calendar year is less than or equal to 0.053 ppm, 
rounded to three decimal places (fractional parts equal to or greater 
than 0.0005 ppm must be rounded up). To demonstrate attainment, an 
annual mean must be based upon hourly data that are at least 75 percent 
complete or upon data derived from manual methods that are at least 75 
percent complete for the scheduled sampling days in each calendar 
quarter.

[50 FR 25544, June 19, 1985]



Sec. 50.12  National primary and secondary ambient air quality standards for lead.

    National primary and secondary ambient air quality standards for 
lead and its compounds, measured as elemental lead by a reference method 
based on appendix G to this part, or by an equivalent method, are: 1.5 
micrograms per cubic meter, maximum arithmetic mean averaged over a 
calendar quarter.

(Secs. 109, 301(a) Clean Air Act as amended (42 U.S.C. 7409, 7601(a)))

[43 FR 46258, Oct. 5, 1978]

Appendix A to Part 50--Reference Method for the Determination of Sulfur 
            Dioxide in the Atmosphere (Pararosaniline Method)

    1.0 Applicability.
    1.1 This method provides a measurement of the concentration of 
sulfur dioxide (SO2) in ambient air for determining 
compliance with the primary and secondary national ambient air quality 
standards for sulfur oxides (sulfur dioxide) as specified in Sec. 50.4 
and Sec. 50.5 of this chapter. The method is applicable to the 
measurement of ambient SO2 concentrations using sampling 
periods ranging from 30 minutes to 24 hours. Additional quality 
assurance procedures and guidance are provided in part 58, appendixes A 
and B, of this chapter and in references 1 and 2.
    2.0 Principle.
    2.1 A measured volume of air is bubbled through a solution of 0.04 M 
potassium tetrachloromercurate (TCM). The SO2 present in the 
air stream reacts with the TCM solution to form a stable 
monochlorosulfonatomercurate(3) complex. Once formed, this complex 
resists air oxidation(4,

[[Page 10]]

5) and is stable in the presence of strong oxidants such as ozone and 
oxides of nitrogen. During subsequent analysis, the complex is reacted 
with acid-bleached pararosaniline dye and formaldehyde to form an 
intensely colored pararosaniline methyl sulfonic acid.(6) The optical 
density of this species is determined spectrophotometrically at 548 nm 
and is directly related to the amount of SO2 collected. The 
total volume of air sampled, corrected to EPA reference conditions (25 
deg.C, 760 mm Hg [101 kPa]), is determined from the measured flow rate 
and the sampling time. The concentration of SO2 in the 
ambient air is computed and expressed in micrograms per standard cubic 
meter (g/std m3).
    3.0 Range.
    3.1 The lower limit of detection of SO2 in 10 mL of TCM 
is 0.75 g (based on collaborative test results).(7) This 
represents a concentration of 25 g SO2/m3 
(0.01 ppm) in an air sample of 30 standard liters (short-term sampling) 
and a concentration of 13 g SO2/m3 (0.005 
ppm) in an air sample of 288 standard liters (long-term sampling). 
Concentrations less than 25 g SO2/m3 can 
be measured by sampling larger volumes of ambient air; however, the 
collection efficiency falls off rapidly at low concentrations.(8, 9) 
Beer's law is adhered to up to 34 g of SO2 in 25 mL 
of final solution. This upper limit of the analysis range represents a 
concentration of 1,130 g SO2/m3 (0.43 
ppm) in an air sample of 30 standard liters and a concentration of 590 
g SO2/m3 (0.23 ppm) in an air sample of 
288 standard liters. Higher concentrations can be measured by collecting 
a smaller volume of air, by increasing the volume of absorbing solution, 
or by diluting a suitable portion of the collected sample with absorbing 
solution prior to analysis.
    4.0 Interferences.
    4.1 The effects of the principal potential interferences have been 
minimized or eliminated in the following manner: Nitrogen oxides by the 
addition of sulfamic acid,(10, 11) heavy metals by the addition of 
ethylenediamine tetracetic acid disodium salt (EDTA) and phosphoric 
acid,(10, 12) and ozone by time delay.(10) Up to 60 g Fe (III), 
22 g V (V), 10 g Cu (II), 10 g Mn (II), and 
10 g Cr (III) in 10 mL absorbing reagent can be tolerated in 
the procedure.(10) No significant interference has been encountered with 
2.3 g NH3.(13)
    5.0 Precision and Accuracy.
    5.1 The precision of the analysis is 4.6 percent (at the 95 percent 
confidence level) based on the analysis of standard sulfite samples.(10)
    5.2 Collaborative test results (14) based on the analysis of 
synthetic test atmospheres (SO2 in scrubbed air) using the 
24-hour sampling procedure and the sulfite-TCM calibration procedure 
show that:

 The replication error varies linearly with concentration from 
2.5 g/m\3\ at concentrations of 100 g/m\3\ 
to 7 g/m\3\ at concentrations of 400 g/
m\3\.
 The day-to-day variability within an individual laboratory 
(repeatability) varies linearly with concentration from 18.1 
g/m\3\ at levels of 100 g/m\3\ to 50.9 
g/m\3\ at levels of 400 g/m\3\.
 The day-to-day variability between two or more laboratories 
(reproducibility) varies linearly with concentration from 
36.9 g/m\3\ at levels of 100 g/m\3\ to 
103.5  g/m\3\ at levels of 400 g/m\3\.
 The method has a concentration-dependent bias, which becomes 
significant at the 95 percent confidence level at the high concentration 
level. Observed values tend to be lower than the expected SO2 
concentration level.

    6.0 Stability.
    6.1 By sampling in a controlled temperature environment of 
15 deg.10  deg.C, greater than 98.9 percent of the 
SO2-TCM complex is retained at the completion of sampling. 
(15) If kept at 5  deg.C following the completion of sampling, the 
collected sample has been found to be stable for up to 30 days.(10) The 
presence of EDTA enhances the stability of SO2 in the TCM 
solution and the rate of decay is independent of the concentration of 
SO2.(16)
    7.0 Apparatus.
    7.1 Sampling.
    7.1.1 Sample probe: A sample probe meeting the requirements of 
section 7 of 40 CFR part 58, appendix E (Teflon or glass with 
residence time less than 20 sec.) is used to transport ambient air to 
the sampling train location. The end of the probe should be designed or 
oriented to preclude the sampling of precipitation, large particles, 
etc. A suitable probe can be constructed from Teflon tubing 
connected to an inverted funnel.
    7.1.2 Absorber--short-term sampling: An all glass midget impinger 
having a solution capacity of 30 mL and a stem clearance of 
41 mm from the bottom of the vessel is used for sampling 
periods of 30 minutes and 1 hour (or any period considerably less than 
24 hours). Such an impinger is shown in Figure 1. These impingers are 
commercially available from distributors such as Ace Glass, 
Incorporated.
    7.1.3 Absorber--24-hour sampling: A polypropylene tube 32 mm in 
diameter and 164 mm long (available from Bel Art Products, Pequammock, 
NJ) is used as the absorber. The cap of the absorber must be a 
polypropylene cap with two ports (rubber stoppers are unacceptable 
because the absorbing reagent can react with the stopper to yield 
erroneously high SO2 concentrations). A glass impinger stem, 
6 mm in diameter and 158 mm long, is inserted into one port of the 
absorber cap. The tip of the stem is tapered to a small diameter orifice 
(0.40.1 mm) such that a No. 79 jeweler's drill bit will pass 
through the opening but a No. 78 drill bit

[[Page 11]]

will not. Clearance from the bottom of the absorber to the tip of the 
stem must be 62 mm. Glass stems can be fabricated by any 
reputable glass blower or can be obtained from a scientific supply firm. 
Upon receipt, the orifice test should be performed to verify the orifice 
size. The 50 mL volume level should be permanently marked on the 
absorber. The assembled absorber is shown in Figure 2.
    7.1.4 Moisture trap: A moisture trap constructed of a glass trap as 
shown in Figure 1 or a polypropylene tube as shown in Figure 2 is placed 
between the absorber tube and flow control device to prevent entrained 
liquid from reaching the flow control device. The tube is packed with 
indicating silica gel as shown in Figure 2. Glass wool may be 
substituted for silica gel when collecting short-term samples (1 hour or 
less) as shown in Figure 1, or for long term (24 hour) samples if flow 
changes are not routinely encountered.
    7.1.5 Cap seals: The absorber and moisture trap caps must seal 
securely to prevent leaks during use. Heat-shrink material as shown in 
Figure 2 can be used to retain the cap seals if there is any chance of 
the caps coming loose during sampling, shipment, or storage.

[[Page 12]]




[[Page 13]]





[[Page 14]]


    7.1.6 Flow control device: A calibrated rotameter and needle valve 
combination capable of maintaining and measuring air flow to within 
2 percent is suitable for short-term sampling but may not be 
used for long-term sampling. A critical orifice can be used for 
regulating flow rate for both long-term and short-term sampling. A 22-
gauge hypodermic needle 25 mm long may be used as a critical orifice to 
yield a flow rate of approximately 1 L/min for a 30-minute sampling 
period. When sampling for 1 hour, a 23-gauge hypodermic needle 16 mm in 
length will provide a flow rate of approximately 0.5 L/min. Flow control 
for a 24-hour sample may be provided by a 27-gauge hypodermic needle 
critical orifice that is 9.5 mm in length. The flow rate should be in 
the range of 0.18 to 0.22 L/min.
    7.1.7 Flow measurement device: Device calibrated as specified in 
9.4.1 and used to measure sample flow rate at the monitoring site.
    7.1.8 Membrane particle filter: A membrane filter of 0.8 to 2 
m porosity is used to protect the flow controller from 
particles during long-term sampling. This item is optional for short-
term sampling.
    7.1.9 Vacuum pump: A vacuum pump equipped with a vacuum gauge and 
capable of maintaining at least 70 kPa (0.7 atm) vacuum differential 
across the flow control device at the specified flow rate is required 
for sampling.
    7.1.10 Temperature control device: The temperature of the absorbing 
solution during sampling must be maintained at 15 deg. 10 
deg.C. As soon as possible following sampling and until analysis, the 
temperature of the collected sample must be maintained at 5 deg. 
5  deg.C. Where an extended period of time may elapse before 
the collected sample can be moved to the lower storage temperature, a 
collection temperature near the lower limit of the 15  10 
deg.C range should be used to minimize losses during this period. 
Thermoelectric coolers specifically designed for this temperature 
control are available commercially and normally operate in the range of 
5 deg. to 15  deg.C. Small refrigerators can be modified to provide the 
required temperature control; however, inlet lines must be insulated 
from the lower temperatures to prevent condensation when sampling under 
humid conditions. A small heating pad may be necessary when sampling at 
low temperatures (<7  deg.C) to prevent the absorbing solution from 
freezing.(17)
    7.1.11 Sampling train container: The absorbing solution must be 
shielded from light during and after sampling. Most commercially 
available sampler trains are enclosed in a light-proof box.
    7.1.12 Timer: A timer is recommended to initiate and to stop 
sampling for the 24-hour period. The timer is not a required piece of 
equipment; however, without the timer a technician would be required to 
start and stop the sampling manually. An elapsed time meter is also 
recommended to determine the duration of the sampling period.
    7.2 Shipping.
    7.2.1 Shipping container: A shipping container that can maintain a 
temperature of 5 deg. 5  deg.C is used for transporting the 
sample from the collection site to the analytical laboratory. Ice 
coolers or refrigerated shipping containers have been found to be 
satisfactory. The use of eutectic cold packs instead of ice will give a 
more stable temperature control. Such equipment is available from Cole-
Parmer Company, 7425 North Oak Park Avenue, Chicago, IL 60648.
    7.3 Analysis.
    7.3.1 Spectrophotometer: A spectrophotometer suitable for 
measurement of absorbances at 548 nm with an effective spectral 
bandwidth of less than 15 nm is required for analysis. If the 
spectrophotometer reads out in transmittance, convert to absorbance as 
follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.000

where:

A = absorbance, and
T = transmittance (0<T<1).

    A standard wavelength filter traceable to the National Bureau of 
Standards is used to verify the wavelength calibration according to the 
procedure enclosed with the filter. The wavelength calibration must be 
verified upon initial receipt of the instrument and after each 160 hours 
of normal use or every 6 months, whichever occurs first.
    7.3.2 Spectrophotometer cells: A set of 1-cm path length cells 
suitable for use in the visible region is used during analysis. If the 
cells are unmatched, a matching correction factor must be determined 
according to Section 10.1.
    7.3.3 Temperature control device: The color development step during 
analysis must be conducted in an environment that is in the range of 
20 deg. to 30  deg.C and controlled to 1  deg.C. Both 
calibration and sample analysis must be performed under identical 
conditions (within 1  deg.C). Adequate temperature control may be 
obtained by means of constant temperature baths, water baths with manual 
temperature control, or temperature controlled rooms.
    7.3.4 Glassware: Class A volumetric glassware of various capacities 
is required for preparing and standardizing reagents and standards and 
for dispensing solutions during analysis. These included pipets, 
volumetric flasks, and burets.
    7.3.5 TCM waste receptacle: A glass waste receptacle is required for 
the storage of spent TCM solution. This vessel should be stoppered and 
stored in a hood at all times.
    8.0 Reagents.
    8.1 Sampling.

[[Page 15]]

    8.1.1 Distilled water: Purity of distilled water must be verified by 
the following procedure:(18)
 Place 0.20 mL of potassium permanganate solution (0.316 g/L), 
500 mL of distilled water, and 1mL of concentrated sulfuric acid in a 
chemically resistant glass bottle, stopper the bottle, and allow to 
stand.
 If the permanganate color (pink) does not disappear completely 
after a period of 1 hour at room temperature, the water is suitable for 
use.
 If the permanganate color does disappear, the water can be 
purified by redistilling with one crystal each of barium hydroxide and 
potassium permanganate in an all glass still.

    8.1.2 Absorbing reagent (0.04 M potassium tetrachloromercurate 
[TCM]): Dissolve 10.86 g mercuric chloride, 0.066 g EDTA, and 6.0 g 
potassium chloride in distilled water and dilute to volume with 
distilled water in a 1,000-mL volumetric flask. (Caution: Mercuric 
chloride is highly poisonous. If spilled on skin, flush with water 
immediately.) The pH of this reagent should be between 3.0 and 5.0 (10) 
Check the pH of the absorbing solution by using pH indicating paper or a 
pH meter. If the pH of the solution is not between 3.0 and 5.0, dispose 
of the solution according to one of the disposal techniques described in 
Section 13.0. The absorbing reagent is normally stable for 6 months. If 
a precipitate forms, dispose of the reagent according to one of the 
procedures described in Section 13.0.
    8.2 Analysis.
    8.2.1 Sulfamic acid (0.6%): Dissolve 0.6 g sulfamic acid in 100 mL 
distilled water. Perpare fresh daily.
    8.2.2 Formaldehyde (0.2%): Dilute 5 mL formaldehyde solution (36 to 
38 percent) to 1,000 mL with distilled water. Prepare fresh daily.
    8.2.3 Stock iodine solution (0.1 N): Place 12.7 g resublimed iodine 
in a 250-mL beaker and add 40 g potassium iodide and 25 mL water. Stir 
until dissolved, transfer to a 1,000 mL volumetric flask and dilute to 
volume with distilled water.
    8.2.4 Iodine solution (0.01 N): Prepare approximately 0.01 N iodine 
solution by diluting 50 mL of stock iodine solution (Section 8.2.3) to 
500 mL with distilled water.
    8.2.5 Starch indicator solution: Triturate 0.4 g soluble starch and 
0.002 g mercuric iodide (preservative) with enough distilled water to 
form a paste. Add the paste slowly to 200 mL of boiling distilled water 
and continue boiling until clear. Cool and transfer the solution to a 
glass stopperd bottle.
    8.2.6 1 N hydrochloric acid: Slowly and while stirring, add 86 mL of 
concentrated hydrochloric acid to 500 mL of distilled water. Allow to 
cool and dilute to 1,000 mL with distilled water.
    8.2.7 Potassium iodate solution: Accurately weigh to the nearest 0.1 
mg, 1.5 g (record weight) of primary standard grade potassium iodate 
that has been previously dried at 180  deg.C for at least 3 hours and 
cooled in a dessicator. Dissolve, then dilute to volume in a 500-mL 
volumetric flask with distilled water.
    8.2.8 Stock sodium thiosulfate solution (0.1 N): Prepare a stock 
solution by dissolving 25 g sodium thiosulfate (Na2 
S2 O35H2 O) in 1,000 mL freshly 
boiled, cooled, distilled water and adding 0.1 g sodium carbonate to the 
solution. Allow the solution to stand at least 1 day before 
standardizing. To standardize, accurately pipet 50 mL of potassium 
iodate solution (Section 8.2.7) into a 500-mL iodine flask and add 2.0 g 
of potassium iodide and 10 mL of 1 N HCl. Stopper the flask and allow to 
stand for 5 minutes. Titrate the solution with stock sodium thiosulfate 
solution (Section 8.2.8) to a pale yellow color. Add 5 mL of starch 
solution (Section 8.2.5) and titrate until the blue color just 
disappears. Calculate the normality (Ns) of the stock sodium 
thiosulfate solution as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.001

where:

M = volume of thiosulfate required in mL, and
W = weight of potassium iodate in g (recorded weight in Section 8.2.7).
[GRAPHIC] [TIFF OMITTED] TC08NO91.002

    8.2.9  Working sodium thiosulfate titrant (0.01 N): Accurately pipet 
100 mL of stock sodium thiosulfate solution (Section 8.2.8) into a 
1,000-mL volumetric flask and dilute to volume with freshly boiled, 
cooled, distilled water. Calculate the normality of the working sodium 
thiosulfate titrant (NT) as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.003

    8.2.10 Standardized sulfite solution for the preparation of working 
sulfite-TCM solution: Dissolve 0.30 g sodium metabisulfite (Na2 
S2 O5) or 0.40 g sodium sulfite (Na2 
SO3) in 500 mL of recently boiled, cooled, distilled water. 
(Sulfite solution is unstable; it is therefore important to use water of 
the highest purity to minimize this instability.) This solution contains 
the equivalent of 320 to 400 g SO2/mL. The actual 
concentration of the solution is determined by adding excess iodine and 
back-titrating with standard sodium thiosulfate solution. To back-
titrate, pipet 50 mL of the 0.01 N iodine solution (Section 8.2.4) into 
each of two 500-mL iodine flasks (A and B). To flask A (blank) add 25 mL 
distilled water, and to flask B (sample)

[[Page 16]]

pipet 25 mL sulfite solution. Stopper the flasks and allow to stand for 
5 minutes. Prepare the working sulfite-TCM solution (Section 8.2.11) 
immediately prior to adding the iodine solution to the flasks. Using a 
buret containing standardized 0.01 N thiosulfate titrant (Section 
8.2.9), titrate the solution in each flask to a pale yellow color. Then 
add 5 mL starch solution (Section 8.2.5) and continue the titration 
until the blue color just disappears.
    8.2.11 Working sulfite-TCM solution: Accurately pipet 5 mL of the 
standard sulfite solution (Section 8.2.10) into a 250-mL volumetric 
flask and dilute to volume with 0.04 M TCM. Calculate the concentration 
of sulfur dioxide in the working solution as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.004

where:

A = volume of thiosulfate titrant required for the blank, mL;
B = volume of thiosulfate titrant required for the sample, mL;
NT = normality of the thiosulfate titrant, from equation (3);
32,000 = milliequivalent weight of SO2, g;
25 = volume of standard sulfite solution, mL; and
0.02 = dilution factor.

    This solution is stable for 30 days if kept at 5  deg.C. (16) If not 
kept at 5  deg.C, prepare fresh daily.
    8.2.12 Purified pararosaniline (PRA) stock solution (0.2% nominal):
    8.2.12.1 Dye specifications--

 The dye must have a maximum absorbance at a wavelength of 540 
nm when assayed in a buffered solution of 0.1 M sodium acetate-acetic 
acid;
 The absorbance of the reagent blank, which is temperature 
sensitive (0.015 absorbance unit/  deg.C), must not exceed 0.170 at 22 
deg.C with a 1-cm optical path length when the blank is prepared 
according to the specified procedure;
 The calibration curve (Section 10.0) must have a slope equal to 
0.0300.002 absorbance unit/g SO2 with a 
1-cm optical path length when the dye is pure and the sulfite solution 
is properly standardized.

    8.2.12.2 Preparation of stock PRA solution-- A specially purified 
(99 to 100 percent pure) solution of pararosaniline, which meets the 
above specifications, is commercially available in the required 0.20 
percent concentration (Harleco Co.). Alternatively, the dye may be 
purified, a stock solution prepared, and then assayed according to the 
procedure as described below.(10)
    8.2.12.3 Purification procedure for PRA--
    1. Place 100 mL each of 1-butanol and 1 N HCl in a large separatory 
funnel (250-mL) and allow to equilibrate. Note: Certain batches of 1-
butanol contain oxidants that create an SO2 demand. Before 
using, check by placing 20 mL of 1-butanol and 5 mL of 20 percent 
potassium iodide (KI) solution in a 50-mL separatory funnel and shake 
thoroughly. If a yellow color appears in the alcohol phase, redistill 
the 1-butanol from silver oxide and collect the middle fraction or 
purchase a new supply of 1-butanol.
    2. Weigh 100 mg of pararosaniline hydrochloride dye (PRA) in a small 
beaker. Add 50 mL of the equilibrated acid (drain in acid from the 
bottom of the separatory funnel in 1.) to the beaker and let stand for 
several minutes. Discard the remaining acid phase in the separatory 
funnel.
    3. To a 125-mL separatory funnel, add 50 mL of the equilibrated 1-
butanol (draw the 1-butanol from the top of the separatory funnel in 
1.). Transfer the acid solution (from 2.) containing the dye to the 
funnel and shake carefully to extract. The violet impurity will transfer 
to the organic phase.
    4. Transfer the lower aqueous phase into another separatory funnel, 
add 20 mL of equilibrated 1-butanol, and extract again.
    5. Repeat the extraction procedure with three more 10-mL portions of 
equilibrated 1-butanol.
    6. After the final extraction, filter the acid phase through a 
cotton plug into a 50-mL volumetric flask and bring to volume with 1 N 
HCl. This stock reagent will be a yellowish red.
    7. To check the purity of the PRA, perform the assay and adjustment 
of concentration (Section 8.2.12.4) and prepare a reagent blank (Section 
11.2); the absorbance of this reagent blank at 540 nm should be less 
than 0.170 at 22  deg.C. If the absorbance is greater than 0.170 under 
these conditions, further extractions should be performed.
    8.2.12.4 PRA assay procedure-- The concentration of pararosaniline 
hydrochloride (PRA) need be assayed only once after purification. It is 
also recommended that commercial solutions of pararosaniline be assayed 
when first purchased. The assay procedure is as follows:(10)
    1. Prepare 1 M acetate-acetic acid buffer stock solution with a pH 
of 4.79 by dissolving

[[Page 17]]

13.61 g of sodium acetate trihydrate in distilled water in a 100-mL 
volumetric flask. Add 5.70 mL of glacial acetic acid and dilute to 
volume with distilled water.
    2. Pipet 1 mL of the stock PRA solution obtained from the 
purification process or from a commercial source into a 100-mL 
volumetric flask and dilute to volume with distilled water.
    3. Transfer a 5-mL aliquot of the diluted PRA solution from 2. into 
a 50-mL volumetric flask. Add 5mL of 1 M acetate-acetic acid buffer 
solution from 1. and dilute the mixture to volume with distilled water. 
Let the mixture stand for 1 hour.
    4. Measure the absorbance of the above solution at 540 nm with a 
spectrophotometer against a distilled water reference. Compute the 
percentage of nominal concentration of PRA by
[GRAPHIC] [TIFF OMITTED] TC08NO91.005

where:

A = measured absorbance of the final mixture (absorbance units);
W = weight in grams of the PRA dye used in the assay to prepare 50 mL of 
stock solution (for example, 0.100 g of dye was used to prepare 50 mL of 
solution in the purification procedure; when obtained from commercial 
sources, use the stated concentration to compute W; for 98% PRA, W=.098 
g.); and
K = 21.3 for spectrophotometers having a spectral bandwidth of less than 
15 nm and a path length of 1 cm.

    8.2.13 Pararosaniline reagent: To a 250-mL volumetric flask, add 20 
mL of stock PRA solution. Add an additional 0.2 mL of stock solution for 
each percentage that the stock assays below 100 percent. Then add 25 mL 
of 3 M phosphoric acid and dilute to volume with distilled water. The 
reagent is stable for at least 9 months. Store away from heat and light.
    9.0 Sampling Procedure.
    9.1 General Considerations. Procedures are described for short-term 
sampling (30-minute and 1-hour) and for long-term sampling (24-hour). 
Different combinations of absorbing reagent volume, sampling rate, and 
sampling time can be selected to meet special needs. For combinations 
other than those specifically described, the conditions must be adjusted 
so that linearity is maintained between absorbance and concentration 
over the dynamic range. Absorbing reagent volumes less than 10 mL are 
not recommended. The collection efficiency is above 98 percent for the 
conditions described; however, the efficiency may be substantially lower 
when sampling concentrations below 25SO2/
m\3\.(8,9)
    9.2 30-Minute and 1-Hour Sampling. Place 10 mL of TCM absorbing 
reagent in a midget impinger and seal the impinger with a thin film of 
silicon stopcock grease (around the ground glass joint). Insert the 
sealed impinger into the sampling train as shown in Figure 1, making 
sure that all connections between the various components are leak tight. 
Greaseless ball joint fittings, heat shrinkable Teflon 
tubing, or Teflon tube fittings may be used to attain 
leakfree conditions for portions of the sampling train that come into 
contact with air containing SO2. Shield the absorbing reagent 
from direct sunlight by covering the impinger with aluminum foil or by 
enclosing the sampling train in a light-proof box. Determine the flow 
rate according to Section 9.4.2. Collect the sample at 10.10 
L/min for 30-minute sampling or 0.5000.05 L/min for 1-hour 
sampling. Record the exact sampling time in minutes, as the sample 
volume will later be determined using the sampling flow rate and the 
sampling time. Record the atmospheric pressure and temperature.
    9.3 24-Hour Sampling. Place 50 mL of TCM absorbing solution in a 
large absorber, close the cap, and, if needed, apply the heat shrink 
material as shown in Figure 3. Verify that the reagent level is at the 
50 mL mark on the absorber. Insert the sealed absorber into the sampling 
train as shown in Figure 2. At this time verify that the absorber 
temperature is controlled to 1510  deg.C. During sampling, 
the absorber temperature must be controlled to prevent decomposition of 
the collected complex. From the onset of sampling until analysis, the 
absorbing solution must be protected from direct sunlight. Determine the 
flow rate according to Section 9.4.2. Collect the sample for 24 hours 
from midnight to midnight at a flow rate of 0.2000.020 L/
min. A start/stop timer is helpful for initiating and stopping sampling 
and an elapsed time meter will be useful for determining the sampling 
time.

[[Page 18]]



    9.4 Flow Measurement.
    9.4.1 Calibration: Flow measuring devices used for the on-site flow 
measurements required in 9.4.2 must be calibrated against a reliable 
flow or volume standard such as an NBS traceable bubble flowmeter or 
calibrated wet test meter. Rotameters or critical orifices used in the 
sampling train may be calibrated, if desired, as a quality control 
check, but such calibration shall not replace the on-site flow 
measurements required by 9.4.2. In-line rotameters, if they are to be 
calibrated, should be calibrated in situ, with the appropriate volume of 
solution in the absorber.
    9.4.2 Determination of flow rate at sampling site: For short-term 
samples, the standard flow rate is determined at the sampling site at 
the initiation and completion of sample collection with a calibrated 
flow measuring device connected to the inlet of the absorber. For 24-
hour samples, the standard flow rate is determined at the time the 
absorber is placed in the sampling train and again when the absorber is 
removed from the train for shipment to the analytical laboratory with a 
calibrated flow measuring device connected to the inlet of the sampling 
train. The flow rate determination must be made with all components of 
the sampling system in operation (e.g., the absorber temperature 
controller and any sample box heaters must also be operating). Equation 
6 may be used to determine the standard flow rate when a calibrated 
positive displacement meter is used as the flow measuring device. Other 
types of calibrated flow measuring devices may also be used to determine 
the flow rate at the sampling site provided that the user applies any 
appropriate corrections to devices for which output is dependent on 
temperature or pressure.

[[Page 19]]

[GRAPHIC] [TIFF OMITTED] TC08NO91.006

where:

Qstd = flow rate at standard conditions, std L/min (25  deg.C 
and 760 mm Hg);
Qact = flow rate at monitoring site conditions, L/min;
Pb = barometric pressure at monitoring site conditions, mm Hg 
or kPa;
RH = fractional relative humidity of the air being measured;
PH2O = vapor pressure of water at the temperature 
of the air in the flow or volume standard, in the same units as 
Pb, (for wet volume standards only, i.e., bubble flowmeter or 
wet test meter; for dry standards, i.e., dry test meter, 
PH2O=0);
Pstd = standard barometric pressure, in the same units as 
Pb (760 mm Hg or 101 kPa); and
Tmeter = temperature of the air in the flow or volume 
standard,  deg.C (e.g., bubble flowmeter).

    If a barometer is not available, the following equation may be used 
to determine the barometric pressure:
[GRAPHIC] [TIFF OMITTED] TC08NO91.007

where:

H = sampling site elevation above sea level in meters.

    If the initial flow rate (Qi) differs from the flow rate 
of the critical orifice or the flow rate indicated by the flowmeter in 
the sampling train (Qc) by more than 5 percent as determined 
by equation (8), check for leaks and redetermine Qi.
[GRAPHIC] [TIFF OMITTED] TC08NO91.008

    Invalidate the sample if the difference between the initial 
(Qi) and final (Qf) flow rates is more than 5 
percent as determined by equation (9):
[GRAPHIC] [TIFF OMITTED] TC08NO91.009

    9.5 Sample Storage and Shipment. Remove the impinger or absorber 
from the sampling train and stopper immediately. Verify that the 
temperature of the absorber is not above 25  deg.C. Mark the level of 
the solution with a temporary (e.g., grease pencil) mark. If the sample 
will not be analyzed within 12 hours of sampling, it must be stored at 
5 deg. 5  deg.C until analysis. Analysis must occur within 
30 days. If the sample is transported or shipped for a period exceeding 
12 hours, it is recommended that thermal coolers using eutectic ice 
packs, refrigerated shipping containers, etc., be used for periods up to 
48 hours. (17) Measure the temperature of the absorber solution when the 
shipment is received. Invalidate the sample if the temperature is above 
10  deg.C. Store the sample at 5 deg. 5  deg.C until it is 
analyzed.
    10.0 Analytical Calibration.
    10.1 Spectrophotometer Cell Matching. If unmatched spectrophotometer 
cells are used, an absorbance correction factor must be determined as 
follows:
    1. Fill all cells with distilled water and designate the one that 
has the lowest absorbance at 548 nm as the reference. (This reference 
cell should be marked as such and continually used for this purpose 
throughout all future analyses.)
    2. Zero the spectrophotometer with the reference cell.
    3. Determine the absorbance of the remaining cells (Ac) 
in relation to the reference cell and record these values for future 
use. Mark all cells in a manner that adequately identifies the 
correction.
    The corrected absorbance during future analyses using each cell is 
determining as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.010

where:

A = corrected absorbance,
Aobs = uncorrected absorbance, and
Ac = cell correction.

    10.2 Static Calibration Procedure (Option 1). Prepare a dilute 
working sulfite-TCM solution by diluting 10 mL of the working sulfite-
TCM solution (Section 8.2.11) to 100 mL with TCM absorbing reagent. 
Following the table below, accurately pipet the indicated volumes of the 
sulfite-TCM solutions into a series of 25-mL volumetric flasks. Add TCM 
absorbing reagent as indicated to bring the volume in each flask to 10 
mL.

[[Page 20]]



------------------------------------------------------------------------
                                        Volume of                Total
                                         sulfite-  Volume of  g
         Sulfite-TCM solution              TCM      TCM, mL       SO2
                                         solution              (approx.*
------------------------------------------------------------------------
Working...............................        4.0        6.0        28.8
Working...............................        3.0        7.0        21.6
Working...............................        2.0        8.0        14.4
Dilute working........................       10.0        0.0         7.2
Dilute working........................        5.0        5.0         3.6
                                              0.0       10.0         0.0
------------------------------------------------------------------------
*Based on working sulfite-TCM solution concentration of 7.2 g
  SO2/mL; the actual total g SO2 must be calculated using
  equation 11 below.

    To each volumetric flask, add 1 mL 0.6% sulfamic acid (Section 
8.2.1), accurately pipet 2 mL 0.2% formaldehyde solution (Section 
8.2.2), then add 5 mL pararosaniline solution (Section 8.2.13). Start a 
laboratory timer that has been set for 30 minutes. Bring all flasks to 
volume with recently boiled and cooled distilled water and mix 
thoroughly. The color must be developed (during the 30-minute period) in 
a temperature environment in the range of 20 deg. to 30  deg.C, which is 
controlled to plus-minus1  deg.C. For increased precision, a 
constant temperature bath is recommended during the color development 
step. After 30 minutes, determine the corrected absorbance of each 
standard at 548 nm against a distilled water reference (Section 10.1). 
Denote this absorbance as (A). Distilled water is used in the reference 
cell rather than the reagant blank because of the temperature 
sensitivity of the reagent blank. Calculate the total micrograms 
SO2 in each solution:
[GRAPHIC] [TIFF OMITTED] TC08NO91.011

where:

VTCM/SO2 = volume of sulfite-TCM solution used, mL;
CTCM/SO2 = concentration of sulfur dioxide in the working 
sulfite-TCM, g SO2/mL (from equation 4); and
D = dilution factor (D = 1 for the working sulfite-TCM solution; D = 0.1 
for the diluted working sulfite-TCM solution).

    A calibration equation is determined using the method of linear 
least squares (Section 12.1). The total micrograms SO2 
contained in each solution is the x variable, and the corrected 
absorbance (eq. 10) associated with each solution is the y variable. For 
the calibration to be valid, the slope must be in the range of 0.030 
plus-minus0.002 absorbance unit/g SO2, 
the intercept as determined by the least squares method must be equal to 
or less than 0.170 absorbance unit when the color is developed at 22 
deg.C (add 0.015 to this 0.170 specification for each  deg.C above 22 
deg.C) and the correlation coefficient must be greater than 0.998. If 
these criteria are not met, it may be the result of an impure dye and/or 
an improperly standardized sulfite-TCM solution. A calibration factor 
(Bs) is determined by calculating the reciprocal of the slope 
and is subsequently used for calculating the sample concentration 
(Section 12.3).
    10.3 Dynamic Calibration Procedures (Option 2). Atmospheres 
containing accurately known concentrations of sulfur dioxide are 
prepared using permeation devices. In the systems for generating these 
atmospheres, the permeation device emits gaseous SO2 at a 
known, low, constant rate, provided the temperature of the device is 
held constant (plus-minus0.1  deg.C) and the device has been 
accurately calibrated at the temperature of use. The SO2 
permeating from the device is carried by a low flow of dry carrier gas 
to a mixing chamber where it is diluted with SO2-free air to 
the desired concentration and supplied to a vented manifold. A typical 
system is shown schematically in Figure 4 and this system and other 
similar systems have been described in detail by O'Keeffe and Ortman; 
(19) Scaringelli, Frey, and Saltzman, (20) and Scaringelli, O'Keeffe, 
Rosenberg, and Bell. (21) Permeation devices may be prepared or 
purchased and in both cases must be traceable either to a National 
Bureau of Standards (NBS) Standard Reference Material (SRM 1625, SRM 
1626, SRM 1627) or to an NBS/EPA-approved commercially available 
Certified Reference Material (CRM). CRM's are described in Reference 22, 
and a list of CRM sources is available from the address shown for 
Reference 22. A recommended protocol for certifying a permeation device 
to an NBS SRM or CRM is given in Section 2.0.7 of Reference 2. Device 
permeation rates of 0.2 to 0.4 g/min, inert gas flows of about 
50 mL/min, and dilution air flow rates from 1.1 to 15 L/min conveniently 
yield standard atmospheres in the range of 25 to 600 g 
SO2/m3 (0.010 to 0.230 ppm).
    10.3.1 Calibration Option 2A (30-minute and 1-hour samples): 
Generate a series of six standard atmospheres of SO2 (e.g., 
0, 50, 100, 200, 350, 500, 750 g/m3) by adjusting 
the dilution flow rates appropriately. The concentration of SO2 
in each atmosphere is calculated as follows:
[GRAPHIC] [TIFF OMITTED] TR31AU93.014

where:


[[Page 21]]


Ca = concentration of SO2 at standard conditions, 
g/m3;
Pr = permeation rate, g/min;
Qd = flow rate of dilution air, std L/min; and
Qp = flow rate of carrier gas across permeation device, std 
L/min.



[[Page 22]]


    Be sure that the total flow rate of the standard exceeds the flow 
demand of the sample train, with the excess flow vented at atmospheric 
pressure. Sample each atmosphere using similar apparatus as shown in 
Figure 1 and under the same conditions as field sampling (i.e., use same 
absorbing reagent volume and sample same volume of air at an equivalent 
flow rate). Due to the length of the sampling periods required, this 
method is not recommended for 24-hour sampling. At the completion of 
sampling, quantitatively transfer the contents of each impinger to one 
of a series of 25-mL volumetric flasks (if 10 mL of absorbing solution 
was used) using small amounts of distilled water for rinse (<5mL). If 
>10 mL of absorbing solution was used, bring the absorber solution in 
each impinger to orginal volume with distilled H2 O and pipet 
10-mL portions from each impinger into a series of 25-mL volumetric 
flasks. If the color development steps are not to be started within 12 
hours of sampling, store the solutions at 5 deg.  5  deg.C. 
Calculate the total micrograms SO2 in each solution as 
follows:
[GRAPHIC] [TIFF OMITTED] TR31AU93.015

where:

Ca = concentration of SO2 in the standard 
atmosphere, g/m\3\ ;
Os = sampling flow rate, std L/min;
t=sampling time, min;
Va = volume of absorbing solution used for color development 
(10 mL); and
Vb = volume of absorbing solution used for sampling, mL.

    Add the remaining reagents for color development in the same manner 
as in Section 10.2 for static solutions. Calculate a calibration 
equation and a calibration factor (Bg) according to Section 
10.2, adhering to all the specified criteria.
    10.3.2 Calibration Option 2B (24-hour samples): Generate a standard 
atmosphere containing approximately 1,050 g SO2/m\3\ 
and calculate the exact concentration according to equation 12. Set up a 
series of six absorbers according to Figure 2 and connect to a common 
manifold for sampling the standard atmosphere. Be sure that the total 
flow rate of the standard exceeds the flow demand at the sample 
manifold, with the excess flow vented at atmospheric pressure. The 
absorbers are then allowed to sample the atmosphere for varying time 
periods to yield solutions containing 0, 0.2, 0.6, 1.0, 1.4, 1.8, and 
2.2 g SO2/mL solution. The sampling times required 
to attain these solution concentrations are calculated as follows:
[GRAPHIC] [TIFF OMITTED] TR31AU93.016

where:

t = sampling time, min;
Vb = volume of absorbing solution used for sampling (50 mL);
Cs = desired concentration of SO2 in the absorbing 
solution, g/mL;
Ca = concentration of the standard atmosphere calculated 
according to equation 12, g/m\3\ ; and
Qs = sampling flow rate, std L/min.

    At the completion of sampling, bring the absorber solutions to 
original volume with distilled water. Pipet a 10-mL portion from each 
absorber into one of a series of 25-mL volumetric flasks. If the color 
development steps are not to be started within 12 hours of sampling, 
store the solutions at 5 deg.  5  deg.C. Add the remaining 
reagents for color development in the same manner as in Section 10.2 for 
static solutions. Calculate the total g SO2 in each 
standard as follows:
[GRAPHIC] [TIFF OMITTED] TR31AU93.017

where:

Va = volume of absorbing solution used for color development 
(10 mL).
All other parameters are defined in equation 14.

    Calculate a calibration equation and a calibration factor 
(Bt) according to Section 10.2 adhering to all the specified 
criteria.
    11.0 Sample Preparation and Analysis.
    11.1 Sample Preparation. Remove the samples from the shipping 
container. If the shipment period exceeded 12 hours from the completion 
of sampling, verify that the temperature is below 10  deg.C. Also, 
compare the solution level to the temporary level mark on the absorber. 
If either the temperature is above 10  deg.C or there was significant 
loss (more than 10 mL) of the sample during shipping, make an 
appropriate notation in the record and invalidate the sample. Prepare 
the samples for analysis as follows:
    1. For 30-minute or 1-hour samples: Quantitatively transfer the 
entire 10 mL amount of absorbing solution to a 25-mL volumetric flask 
and rinse with a small amount (<5 mL) of distilled water.
    2. For 24-hour samples: If the volume of the sample is less than the 
original 50-mL volume (permanent mark on the absorber), adjust the 
volume back to the original volume with distilled water to compensate 
for water lost to evaporation during sampling. If the final volume is 
greater than the original volume, the volume must be measured using a 
graduated cylinder. To analyze, pipet 10 mL

[[Page 23]]

of the solution into a 25-mL volumetric flask.
    11.2 Sample Analysis. For each set of determinations, prepare a 
reagent blank by adding 10 mL TCM absorbing solution to a 25-mL 
volumetric flask, and two control standards containing approximately 5 
and 15 g SO2, respectively. The control standards 
are prepared according to Section 10.2 or 10.3. The analysis is carried 
out as follows:
    1. Allow the sample to stand 20 minutes after the completion of 
sampling to allow any ozone to decompose (if applicable).
    2. To each 25-mL volumetric flask containing reagent blank, sample, 
or control standard, add 1 mL of 0.6% sulfamic acid (Section 8.2.1) and 
allow to react for 10 min.
    3. Accurately pipet 2 mL of 0.2% formaldehyde solution (Section 
8.2.2) and then 5 mL of pararosaniline solution (Section 8.2.13) into 
each flask. Start a laboratory timer set at 30 minutes.
    4. Bring each flask to volume with recently boiled and cooled 
distilled water and mix thoroughly.
    5. During the 30 minutes, the solutions must be in a temperature 
controlled environment in the range of 20 deg. to 30  deg.C maintained 
to plus-minus 1  deg.C. This temperature must also be within 
1  deg.C of that used during calibration.
    6. After 30 minutes and before 60 minutes, determine the corrected 
absorbances (equation 10) of each solution at 548 nm using 1-cm optical 
path length cells against a distilled water reference (Section 10.1). 
(Distilled water is used as a reference instead of the reagent blank 
because of the sensitivity of the reagent blank to temperature.)
    7. Do not allow the colored solution to stand in the cells because a 
film may be deposited. Clean the cells with isopropyl alcohol after use.
    8. The reagent blank must be within 0.03 absorbance units of the 
intercept of the calibration equation determined in Section 10.
    11.3 Absorbance range. If the absorbance of the sample solution 
ranges between 1.0 and 2.0, the sample can be diluted 1:1 with a portion 
of the reagent blank and the absorbance redetermined within 5 minutes. 
Solutions with higher absorbances can be diluted up to sixfold with the 
reagent blank in order to obtain scale readings of less than 1.0 
absorbance unit. However, it is recommended that a smaller portion (<10 
mL) of the original sample be reanalyzed (if possible) if the sample 
requires a dilution greater than 1:1.
    11.4 Reaqent disposal. All reagents containing mercury compounds 
must be stored and disposed of using one of the procedures contained in 
Section 13. Until disposal, the discarded solutions can be stored in 
closed glass containers and should be left in a fume hood.
    12.0 Calculations.
    12.1 Calibration Slope, Intercept, and Correlation Coefficient. The 
method of least squares is used to calculate a calibration equation in 
the form of:
[GRAPHIC] [TIFF OMITTED] TC08NO91.012

where:

y = corrected absorbance,
m = slope, absorbance unit/g SO2,
x = micrograms of SO2,
b = y intercept (absorbance units).

    The slope (m), intercept (b), and correlation coefficient (r) are 
calculated as follows:
[GRAPHIC] [TIFF OMITTED] TR31AU93.018

[GRAPHIC] [TIFF OMITTED] TR31AU93.019

[GRAPHIC] [TIFF OMITTED] TR31AU93.020

where n is the number of calibration points.
    A data form (Figure 5) is supplied for easily organizing calibration 
data when the slope, intercept, and correlation coefficient are 
calculated by hand.
    12.2 Total Sample Volume. Determine the sampling volume at standard 
conditions as follows:
[GRAPHIC] [TIFF OMITTED] TR31AU93.021

where:

Vstd = sampling volume in std L,
Qi = standard flow rate determined at the initiation of 
sampling in std L/min,
Qf = standard flow rate determined at the completion of 
sampling is std L/min, and
t = total sampling time, min.

    12.3 Sulfur Dioxide Concentration. Calculate and report the 
concentration of each sample as follows:
[GRAPHIC] [TIFF OMITTED] TR31AU93.022

where:

A = corrected absorbance of the sample solution, from equation (10);
Ao = corrected absorbance of the reagent blank, using 
equation (10);
Bx = calibration factor equal to Bs, 
Bg, or Bt depending on the calibration procedure 
used, the reciprocal of the slope of the calibration equation;
Va = volume of absorber solution analyzed, mL;
Vb = total volume of solution in absorber (see 11.1-2), mL; 
and
Vstd = standard air volume sampled, std L (from Section 
12.2).

[[Page 24]]



                                                    Data Form
                                             [For hand calculations]
----------------------------------------------------------------------------------------------------------------
                                                      Absor- bance
     Calibration point no.       Micro- grams So2        units
----------------------------------------------------------------------------------------------------------------
                                       (x)                (y)                 x2                xy           y2
1.............................  .................  .................  .................  ................  .....
2.............................  .................  .................  .................  ................  .....
3.............................  .................  .................  .................  ................  .....
4.............................  .................  .................  .................  ................  .....
5.............................  .................  .................  .................  ................  .....
6.............................  .................  .................  .................  ................  .....
----------------------------------------------------------------------------------------------------------------

 x=______   y=______   x\2\=______  
xy______  y\2\______  
n=______ (number of pairs of coordinates.)
_______________________________________________________________________

Figure 5. Data form for hand calculations.

    12.4 Control Standards. Calculate the analyzed micrograms of 
SO2 in each control standard as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.070

where:

Cq = analyzed g SO2 in each control 
standard,
A = corrected absorbance of the control standard, and
Ao = corrected absorbance of the reagent blank.

    The difference between the true and analyzed values of the control 
standards must not be greater than 1 g. If the difference is 
greater than 1 g, the source of the discrepancy must be 
identified and corrected.
    12.5 Conversion of g/m3 to ppm (v/v). If 
desired, the concentration of sulfur dioxide at reference conditions can 
be converted to ppm SO2 (v/v) as follows:
[GRAPHIC] [TIFF OMITTED] TR31AU93.023

    13.0 The TCM absorbing solution and any reagents containing mercury 
compounds must be treated and disposed of by one of the methods 
discussed below. Both methods remove greater than 99.99 percent of the 
mercury.
    13.1 Disposal of Mercury-Containing Solutions.
    13.2 Method for Forming an Amalgam.
    1. Place the waste solution in an uncapped vessel in a hood.
    2. For each liter of waste solution, add approximately 10 g of 
sodium carbonate until neutralization has occurred (NaOH may have to be 
used).
    3. Following neutralization, add 10 g of granular zinc or magnesium.
    4. Stir the solution in a hood for 24 hours. Caution must be 
exercised as hydrogen gas is evolved by this treatment process.
    5. After 24 hours, allow the solution to stand without stirring to 
allow the mercury amalgam (solid black material) to settle to the bottom 
of the waste receptacle.
    6. Upon settling, decant and discard the supernatant liquid.
    7. Quantitatively transfer the solid material to a container and 
allow to dry.
    8. The solid material can be sent to a mercury reclaiming plant. It 
must not be discarded.
    13.3 Method Using Aluminum Foil Strips.
    1. Place the waste solution in an uncapped vessel in a hood.
    2. For each liter of waste solution, add approximately 10 g of 
aluminum foil strips. If all the aluminum is consumed and no gas is 
evolved, add an additional 10 g of foil. Repeat until the foil is no 
longer consumed and allow the gas to evolve for 24 hours.
    3. Decant the supernatant liquid and discard.
    4. Transfer the elemental mercury that has settled to the bottom of 
the vessel to a storage container.
    5. The mercury can be sent to a mercury reclaiming plant. It must 
not be discarded.
    14.0 References for SO2 Method.
    1. Quality Assurance Handbook for Air Pollution Measurement Systems, 
Volume I, Principles. EPA-600/9-76-005, U.S. Environmental Protection 
Agency, Research Triangle Park, NC 27711, 1976.
    2. Quality Assurance Handbook for Air Pollution Measurement Systems, 
Volume II, Ambient Air Specific Methods. EPA-600/4-77-027a, U.S. 
Environmental Protection Agency, Research Triangle Park, NC 27711, 1977.
    3. Dasqupta, P. K., and K. B. DeCesare. Stability of Sulfur Dioxide 
in Formaldehyde and Its Anomalous Behavior in Tetrachloromercurate (II). 
Submitted for publication in Atmospheric Environment, 1982.
    4. West, P. W., and G. C. Gaeke. Fixation of Sulfur Dioxide as 
Disulfitomercurate (II) and Subsequent Colorimetric Estimation. Anal. 
Chem., 28:1816, 1956.
    5. Ephraim, F. Inorganic Chemistry. P. C. L. Thorne and E. R. 
Roberts, Eds., 5th Edition, Interscience, 1948, p. 562.
    6. Lyles, G. R., F. B. Dowling, and V. J. Blanchard. Quantitative 
Determination of Formaldehyde in the Parts Per Hundred Million 
Concentration Level. J. Air. Poll. Cont. Assoc., Vol. 15(106), 1965.
    7. McKee, H. C., R. E. Childers, and O. Saenz, Jr. Collaborative 
Study of Reference Method for Determination of Sulfur Dioxide in the 
Atmosphere (Pararosaniline Method). EPA-APTD-0903, U.S. Environmental 
Protection Agency, Research Triangle Park, NC 27711, September 1971.
    8. Urone, P., J. B. Evans, and C. M. Noyes. Tracer Techniques in 
Sulfur--Air Pollution Studies Apparatus and Studies of Sulfur Dioxide 
Colorimetric and Conductometric Methods. Anal. Chem., 37: 1104, 1965.

[[Page 25]]

    9. Bostrom, C. E. The Absorption of Sulfur Dioxide at Low 
Concentrations (pphm) Studied by an Isotopic Tracer Method. Intern. J. 
Air Water Poll., 9:333, 1965.
    10. Scaringelli, F. P., B. E. Saltzman, and S. A. Frey. 
Spectrophotometric Determination of Atmospheric Sulfur Dioxide. Anal. 
Chem., 39: 1709, 1967.
    11. Pate, J. B., B. E. Ammons, G. A. Swanson, and J. P. Lodge, Jr. 
Nitrite Interference in Spectrophotometric Determination of Atmospheric 
Sulfur Dioxide. Anal. Chem., 37:942, 1965.
    12. Zurlo, N., and A. M. Griffini. Measurement of the Sulfur Dioxide 
Content of the Air in the Presence of Oxides of Nitrogen and Heavy 
Metals. Medicina Lavoro, 53:330, 1962.
    13. Rehme, K. A., and F. P. Scaringelli. Effect of Ammonia on the 
Spectrophotometric Determination of Atmospheric Concentrations of Sulfur 
Dioxide. Anal. Chem., 47:2474, 1975.
    14. McCoy, R. A., D. E. Camann, and H. C. McKee. Collaborative Study 
of Reference Method for Determination of Sulfur Dioxide in the 
Atmosphere (Pararosaniline Method) (24-Hour Sampling). EPA-650/4-74-027, 
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, 
December 1973.
    15. Fuerst, R. G. Improved Temperature Stability of Sulfur Dioxide 
Samples Collected by the Federal Reference Method. EPA-600/4-78-018, 
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, 
April 1978.
    16. Scaringelli, F. P., L. Elfers, D. Norris, and S. Hochheiser. 
Enhanced Stability of Sulfur Dioxide in Solution. Anal. Chem., 42:1818, 
1970.
    17. Martin, B. E. Sulfur Dioxide Bubbler Temperature Study. EPA-600/
4-77-040, U.S. Environmental Protection Agency, Research Triangle Park, 
NC 27711, August 1977.
    18. American Society for Testing and Materials. ASTM Standards, 
Water; Atmospheric Analysis. Part 23. Philadelphia, PA, October 1968, p. 
226.
    19. O'Keeffe, A. E., and G. C. Ortman. Primary Standards for Trace 
Gas Analysis. Anal. Chem., 38:760, 1966.
    20. Scaringelli, F. P., S. A. Frey, and B. E. Saltzman. Evaluation 
of Teflon Permeation Tubes for Use with Sulfur Dioxide. Amer. Ind. 
Hygiene Assoc. J., 28:260, 1967.
    21. Scaringelli, F. P., A. E. O'Keeffe, E. Rosenberg, and J. P. 
Bell, Preparation of Known Concentrations of Gases and Vapors With 
Permeation Devices Calibrated Gravimetrically. Anal. Chem., 42:871, 
1970.
    22. A Procedure for Establishing Traceability of Gas Mixtures to 
Certain National Bureau of Standards Standard Reference Materials. EPA-
600/7-81-010, U.S. Environmental Protection Agency, Environmental 
Monitoring Systems Laboratory (MD-77), Research Triangle Park, NC 27711, 
January 1981.

[47 FR 54899, Dec. 6, 1982; 48 FR 17355, Apr. 22, 1983]

    Appendix B to Part 50--Reference Method for the Determination of 
   Suspended Particulate Matter in the Atmosphere (High-Volume Method)

    1.0 Applicability.
    1.1 This method provides a measurement of the mass concentration of 
total suspended particulate matter (TSP) in ambient air for determining 
compliance with the primary and secondary national ambient air quality 
standards for particulate matter as specified in Sec. 50.6 and Sec. 50.7 
of this chapter. The measurement process is nondestructive, and the size 
of the sample collected is usually adequate for subsequent chemical 
analysis. Quality assurance procedures and guidance are provided in part 
58, appendixes A and B, of this chapter and in References 1 and 2.
    2.0 Principle.
    2.1 An air sampler, properly located at the measurement site, draws 
a measured quantity of ambient air into a covered housing and through a 
filter during a 24-hr (nominal) sampling period. The sampler flow rate 
and the geometry of the shelter favor the collection of particles up to 
25-50 m (aerodynamic diameter), depending on wind speed and 
direction.(3) The filters used are specified to have a minimum 
collection efficiency of 99 percent for 0.3 m (DOP) particles 
(see Section 7.1.4).
    2.2 The filter is weighed (after moisture equilibration) before and 
after use to determine the net weight (mass) gain. The total volume of 
air sampled, corrected to EPA standard conditions (25  deg.C, 760 mm Hg 
[101 kPa]), is determined from the measured flow rate and the sampling 
time. The concentration of total suspended particulate matter in the 
ambient air is computed as the mass of collected particles divided by 
the volume of air sampled, corrected to standard conditions, and is 
expressed in micrograms per standard cubic meter (g/std 
m3). For samples collected at temperatures and pressures 
significantly different than standard conditions, these corrected 
concentrations may differ substantially from actual concentrations 
(micrograms per actual cubic meter), particularly at high elevations. 
The actual particulate matter concentration can be calculated from the 
corrected concentration using the actual temperature and pressure during 
the sampling period.
    3.0 Range.
    3.1 The approximate concentration range of the method is 2 to 750 
g/std m3. The upper limit is determined by the point 
at which the sampler can no longer maintain the specified

[[Page 26]]

flow rate due to the increased pressure drop of the loaded filter. This 
point is affected by particle size distribution, moisture content of the 
collected particles, and variability from filter to filter, among other 
things. The lower limit is determined by the sensitivity of the balance 
(see Section 7.10) and by inherent sources of error (see Section 6).
    3.2 At wind speeds between 1.3 and 4.5 m/sec (3 and 10 mph), the 
high-volume air sampler has been found to collect particles up to 25 to 
50 m, depending on wind speed and direction.(3) For the filter 
specified in Section 7.1, there is effectively no lower limit on the 
particle size collected.
    4.0 Precision.
    4.1 Based upon collaborative testing, the relative standard 
deviation (coefficient of variation) for single analyst precision 
(repeatability) of the method is 3.0 percent. The corresponding value 
for interlaboratory precision (reproducibility) is 3.7 percent.(4)
    5.0 Accuracy.
    5.1 The absolute accuracy of the method is undefined because of the 
complex nature of atmospheric particulate matter and the difficulty in 
determining the ``true'' particulate matter concentration. This method 
provides a measure of particulate matter concentration suitable for the 
purpose specified under Section 1.0, Applicability.
    6.0 Inherent Sources of Error.
    6.1 Airflow variation. The weight of material collected on the 
filter represents the (integrated) sum of the product of the 
instantaneous flow rate times the instantaneous particle concentration. 
Therefore, dividing this weight by the average flow rate over the 
sampling period yields the true particulate matter concentration only 
when the flow rate is constant over the period. The error resulting from 
a nonconstant flow rate depends on the magnitude of the instantaneous 
changes in the flow rate and in the particulate matter concentration. 
Normally, such errors are not large, but they can be greatly reduced by 
equipping the sampler with an automatic flow controlling mechanism that 
maintains constant flow during the sampling period. Use of a contant 
flow controller is recommended.*
---------------------------------------------------------------------------

    *At elevated altitudes, the effectiveness of automatic flow 
controllers may be reduced because of a reduction in the maximum sampler 
flow.
---------------------------------------------------------------------------

    6.2 Air volume measurement. If the flow rate changes substantially 
or nonuniformly during the sampling period, appreciable error in the 
estimated air volume may result from using the average of the 
presampling and postsampling flow rates. Greater air volume measurement 
accuracy may be achieved by (1) equipping the sampler with a flow 
controlling mechanism that maintains constant air flow during the 
sampling period,* (2) using a calibrated, continuous flow rate recording 
device to record the actual flow rate during the samping period and 
integrating the flow rate over the period, or (3) any other means that 
will accurately measure the total air volume sampled during the sampling 
period. Use of a continuous flow recorder is recommended, particularly 
if the sampler is not equipped with a constant flow controller.
    6.3 Loss of volatiles. Volatile particles collected on the filter 
may be lost during subsequent sampling or during shipment and/or storage 
of the filter prior to the postsampling weighing.(5) Although such 
losses are largely unavoidable, the filter should be reweighed as soon 
after sampling as practical.
    6.4 Artifact particulate matter. Artifact particulate matter can be 
formed on the surface of alkaline glass fiber filters by oxidation of 
acid gases in the sample air, resulting in a higher than true TSP 
determination.(6 7) This effect usually occurs early in the sample 
period and is a function of the filter pH and the presence of acid 
gases. It is generally believed to account for only a small percentage 
of the filter weight gain, but the effect may become more significant 
where relatively small particulate weights are collected.
    6.5 Humidity. Glass fiber filters are comparatively insensitive to 
changes in relative humidity, but collected particulate matter can be 
hygroscopic.(8) The moisture conditioning procedure minimizes but may 
not completely eliminate error due to moisture.
    6.6 Filter handling. Careful handling of the filter between the 
presampling and postsampling weighings is necessary to avoid errors due 
to loss of fibers or particles from the filter. A filter paper cartridge 
or cassette used to protect the filter can minimize handling errors. 
(See Reference 2, Section 2).
    6.7 Nonsampled particulate matter. Particulate matter may be 
deposited on the filter by wind during periods when the sampler is 
inoperative. (9) It is recommended that errors from this source be 
minimized by an automatic mechanical device that keeps the filter 
covered during nonsampling periods, or by timely installation and 
retrieval of filters to minimize the nonsampling periods prior to and 
following operation.
    6.8 Timing errors. Samplers are normally controlled by clock timers 
set to start and stop the sampler at midnight. Errors in the nominal 
1,440-min sampling period may result from a power interruption during 
the sampling period or from a discrepancy between the start or stop time 
recorded on the filter information record and the actual start or stop 
time of the sampler. Such discrepancies may be caused by (1) poor 
resolution of the timer set-points, (2) timer error due to power 
interruption, (3) missetting of

[[Page 27]]

the timer, or (4) timer malfunction. In general, digital electronic 
timers have much better set-point resolution than mechanical timers, but 
require a battery backup system to maintain continuity of operation 
after a power interruption. A continuous flow recorder or elapsed time 
meter provides an indication of the sampler run-time, as well as 
indication of any power interruption during the sampling period and is 
therefore recommended.
    6.9 Recirculation of sampler exhaust. Under stagnant wind 
conditions, sampler exhaust air can be resampled. This effect does not 
appear to affect the TSP measurement substantially, but may result in 
increased carbon and copper in the collected sample. (10) This problem 
can be reduced by ducting the exhaust air well away, preferably 
downwind, from the sampler.
    7.0 Apparatus.
    (See References 1 and 2 for quality assurance information.)
    Note: Samplers purchased prior to the effective date of this 
amendment are not subject to specifications preceded by ().
    7.1 Filter. (Filters supplied by the Environmental Protection Agency 
can be assumed to meet the following criteria. Additional specifications 
are required if the sample is to be analyzed chemically.)
    7.1.1 Size: 20.3  0.2  x 25.4  0.2 cm 
(nominal 8  x 10 in).
    7.1.2 Nominal exposed area: 406.5 cm\2\ (63 in\2\).
    7.1.3. Material: Glass fiber or other relatively inert, 
nonhygroscopic material. (8)
    7.1.4 Collection efficiency: 99 percent minimum as measured by the 
DOP test (ASTM-2986) for particles of 0.3 m diameter.
    7.1.5 Recommended pressure drop range: 42-54 mm Hg (5.6-7.2 kPa) at 
a flow rate of 1.5 std m\3\/min through the nominal exposed area.
    7.1.6 pH: 6 to 10. (11)
    7.1.7 Integrity: 2.4 mg maximum weight loss. (11)
    7.1.8 Pinholes: None.
    7.1.9 Tear strength: 500 g minimum for 20 mm wide strip cut from 
filter in weakest dimension. (See ASTM Test D828-60).
    7.1.10 Brittleness: No cracks or material separations after single 
lengthwise crease.
    7.2 Sampler. The air sampler shall provide means for drawing the air 
sample, via reduced pressure, through the filter at a uniform face 
velocity.
    7.2.1 The sampler shall have suitable means to:
    a. Hold and seal the filter to the sampler housing.
    b. Allow the filter to be changed conveniently.
    c. Preclude leaks that would cause error in the measurement of the 
air volume passing through the filter.
    d. () Manually adjust the flow rate to accommodate 
variations in filter pressure drop and site line voltage and altitude. 
The adjustment may be accomplished by an automatic flow controller or by 
a manual flow adjustment device. Any manual adjustment device must be 
designed with positive detents or other means to avoid unintentional 
changes in the setting.
---------------------------------------------------------------------------

    () See note at beginning of Section 7 of this appendix.
---------------------------------------------------------------------------

    7.2.2 Minimum sample flow rate, heavily loaded filter: 1.1 
m3/min (39 ft3/min).
---------------------------------------------------------------------------

     These specifications are in actual air volume 
units; to convert to EPA standard air volume units, multiply the 
specifications by (Pb/Pstd)(298/T) where 
Pb and T are the barometric pressure in mm Hg (or kPa) and 
the temperature in K at the sampler, and Pstd is 760 mm Hg 
(or 101 kPa).
---------------------------------------------------------------------------

    7.2.3 Maximum sample flow rate, clean filter: 1.7 m3/min 
(60 ft3/min).
    7.2.4 Blower Motor: The motor must be capable of continuous 
operation for 24-hr periods.
    7.3 Sampler shelter.
    7.3.1 The sampler shelter shall:
    a. Maintain the filter in a horizontal position at least 1 m above 
the sampler supporting surface so that sample air is drawn downward 
through the filter.
    b. Be rectangular in shape with a gabled roof, similar to the design 
shown in Figure 1.
    c. Cover and protect the filter and sampler from precipitation and 
other weather.
    d. Discharge exhaust air at least 40 cm from the sample air inlet.
    e. Be designed to minimize the collection of dust from the 
supporting surface by incorporating a baffle between the exhaust outlet 
and the supporting surface.
    7.3.2 The sampler cover or roof shall overhang the sampler housing 
somewhat, as shown in Figure 1, and shall be mounted so as to form an 
air inlet gap between the cover and the sampler housing walls. 
 This sample air inlet should be approximately 
uniform on all sides of the sampler.  The area of 
the sample air inlet must be sized to provide an effective particle 
capture air velocity of between 20 and 35 cm/sec at the recommended 
operational flow rate. The capture velocity is the sample air flow rate 
divided by the inlet area measured in a horizontal plane at the lower 
edge of the cover.  Ideally, the inlet area and 
operational flow rate should be selected to obtain a capture air 
velocity of 25 2 cm/sec.
    7.4 Flow rate measurement devices.
    7.4.1 The sampler shall incorporate a flow rate measurement device 
capable of indicating the total sampler flow rate. Two common types of 
flow indicators covered in the calibration procedure are (1) an 
electronic mass flowmeter and (2) an orifice or orifices

[[Page 28]]

located in the sample air stream together with a suitable pressure 
indicator such as a manometer, or aneroid pressure gauge. A pressure 
recorder may be used with an orifice to provide a continuous record of 
the flow. Other types of flow indicators (including rotameters) having 
comparable precision and accuracy are also acceptable.
    7.4.2  The flow rate measurement device must be capable of 
being calibrated and read in units corresponding to a flow rate which is 
readable to the nearest 0.02 std m3/min over the range 1.0 to 
1.8 std m3/min.
    7.5 Thermometer, to indicate the approximate air temperature at the 
flow rate measurement orifice, when temperature corrections are used.
    7.5.1 Range: -40 deg. to +50  deg.C (223-323 K).
    7.5.2 Resolution: 2  deg.C (2 K).
    7.6 Barometer, to indicate barometric pressure at the flow rate 
measurement orifice, when pressure corrections are used.
    7.6.1 Range: 500 to 800 mm Hg (66-106 kPa).
    7.6.2 Resolution: 5 mm Hg (0.67 kPa).
    7.7 Timing/control device.
    7.7.1 The timing device must be capable of starting and stopping the 
sampler to obtain an elapsed run-time of 24 hr 1 hr (1,440 
60 min).
    7.7.2 Accuracy of time setting: 30 min, or better. (See 
Section 6.8).
    7.8 Flow rate transfer standard, traceable to a primary standard. 
(See Section 9.2.)
    7.8.1 Approximate range: 1.0 to 1.8 m3/min.
    7.8.2 Resolution: 0.02 m3/min.
    7.8.3 Reproducibility: 2 percent (2 times coefficient of 
variation) over normal ranges of ambient temperature and pressure for 
the stated flow rate range. (See Reference 2, Section 2.)
    7.8.4 Maximum pressure drop at 1.7 std m3/min; 50 cm H2 O 
(5 kPa).
    7.8.5 The flow rate transfer standard must connect without leaks to 
the inlet of the sampler and measure the flow rate of the total air 
sample.
    7.8.6 The flow rate transfer standard must include a means to vary 
the sampler flow rate over the range of 1.0 to 1.8 m3/min 
(35-64 ft3/min) by introducing various levels of flow 
resistance between the sampler and the transfer standard inlet.
    7.8.7 The conventional type of flow transfer standard consists of: 
An orifice unit with adapter that connects to the inlet of the sampler, 
a manometer or other device to measure orifice pressure drop, a means to 
vary the flow through the sampler unit, a thermometer to measure the 
ambient temperature, and a barometer to measure ambient pressure. Two 
such devices are shown in Figures 2a and 2b. Figure 2a shows multiple 
fixed resistance plates, which necessitate disassembly of the unit each 
time the flow resistance is changed. A preferable design, illustrated in 
Figure 2b, has a variable flow restriction that can be adjusted 
externally without disassembly of the unit. Use of a conventional, 
orifice-type transfer standard is assumed in the calibration procedure 
(Section 9). However, the use of other types of transfer standards 
meeting the above specifications, such as the one shown in Figure 2c, 
may be approved; see the note following Section 9.1.
    7.9 Filter conditioning environment
    7.9.1 Controlled temperature: between 15 deg. and 30  deg.C with 
less than plus-minus3  deg.C variation during equilibration 
period.
    7.9.2 Controlled humidity: Less than 50 percent relative humidity, 
constant within plus-minus5 percent.
    7.10 Analytical balance.
    7.10.1 Sensitivity: 0.1 mg.
    7.10.2 Weighing chamber designed to accept an unfolded 20.3 x 25.4 
cm (8 x 10 in) filter.
    7.11 Area light source, similar to X-ray film viewer, to backlight 
filters for visual inspection.
    7.12 Numbering device, capable of printing identification numbers on 
the filters before they are placed in the filter conditioning 
environment, if not numbered by the supplier.
    8.0 Procedure.
    (See References 1 and 2 for quality assurance information.)
    8.1 Number each filter, if not already numbered, near its edge with 
a unique identification number.
    8.2 Backlight each filter and inspect for pinholes, particles, and 
other imperfections; filters with visible imperfections must not be 
used.
    8.3 Equilibrate each filter in the conditioning environment for at 
least 24-hr.
    8.4 Following equilibration, weigh each filter to the nearest 
milligram and record this tare weight (Wi) with the filter 
identification number.
    8.5 Do not bend or fold the filter before collection of the sample.
    8.6 Open the shelter and install a numbered, preweighed filter in 
the sampler, following the sampler manufacturer's instructions. During 
inclement weather, precautions must be taken while changing filters to 
prevent damage to the clean filter and loss of sample from or damage to 
the exposed filter. Filter cassettes that can be loaded and unloaded in 
the laboratory may be used to minimize this problem (See Section 6.6).
    8.7 Close the shelter and run the sampler for at least 5 min to 
establish run-temperature conditions.
    8.8 Record the flow indicator reading and, if needed, the barometric 
pressure (P 3) and the ambient temperature (T 3) 
see NOTE following step 8.12). Stop the sampler. Determine the sampler 
flow rate (see Section 10.1); if it is outside the acceptable range (1.1 
to 1.7 m3/min [39-60 ft3/min]), use a different 
filter, or adjust the sampler flow rate. Warning: Substantial flow 
adjustments may affect the

[[Page 29]]

calibration of the orifice-type flow indicators and may necessitate 
recalibration.
    8.9 Record the sampler identification information (filter number, 
site location or identification number, sample date, and starting time).
    8.10 Set the timer to start and stop the sampler such that the 
sampler runs 24-hrs, from midnight to midnight (local time).
    8.11 As soon as practical following the sampling period, run the 
sampler for at least 5 min to again establish run-temperature 
conditions.
    8.12 Record the flow indicator reading and, if needed, the 
barometric pressure (P 3) and the ambient temperature (T 
3).
    Note: No onsite pressure or temperature measurements are necessary 
if the sampler flow indicator does not require pressure or temperature 
corrections (e.g., a mass flowmeter) or if average barometric pressure 
and seasonal average temperature for the site are incorporated into the 
sampler calibration (see step 9.3.9). For individual pressure and 
temperature corrections, the ambient pressure and temperature can be 
obtained by onsite measurements or from a nearby weather station. 
Barometric pressure readings obtained from airports must be station 
pressure, not corrected to sea level, and may need to be corrected for 
differences in elevation between the sampler site and the airport. For 
samplers having flow recorders but not constant flow controllers, the 
average temperature and pressure at the site during the sampling period 
should be estimated from weather bureau or other available data.
    8.13 Stop the sampler and carefully remove the filter, following the 
sampler manufacturer's instructions. Touch only the outer edges of the 
filter. See the precautions in step 8.6.
    8.14 Fold the filter in half lengthwise so that only surfaces with 
collected particulate matter are in contact and place it in the filter 
holder (glassine envelope or manila folder).
    8.15 Record the ending time or elapsed time on the filter 
information record, either from the stop set-point time, from an elapsed 
time indicator, or from a continuous flow record. The sample period must 
be 1,440  60 min. for a valid sample.
    8.16 Record on the filter information record any other factors, such 
as meteorological conditions, construction activity, fires or dust 
storms, etc., that might be pertinent to the measurement. If the sample 
is known to be defective, void it at this time.
    8.17 Equilibrate the exposed filter in the conditioning environment 
for at least 24-hrs.
    8.18 Immediately after equilibration, reweigh the filter to the 
nearest milligram and record the gross weight with the filter 
identification number. See Section 10 for TSP concentration 
calculations.
    9.0 Calibration.
    9.1 Calibration of the high volume sampler's flow indicating or 
control device is necessary to establish traceability of the field 
measurement to a primary standard via a flow rate transfer standard. 
Figure 3a illustrates the certification of the flow rate transfer 
standard and Figure 3b illustrates its use in calibrating a sampler flow 
indicator. Determination of the corrected flow rate from the sampler 
flow indicator, illustrated in Figure 3c, is addressed in Section 10.1
    Note: The following calibration procedure applies to a conventional 
orifice-type flow transfer standard and an orifice-type flow indicator 
in the sampler (the most common types). For samplers using a pressure 
recorder having a square-root scale, 3 other acceptable calibration 
procedures are provided in Reference 12. Other types of transfer 
standards may be used if the manufacturer or user provides an 
appropriately modified calibration procedure that has been approved by 
EPA under Section 2.8 of appendix C to part 58 of this chapter.
    9.2 Certification of the flow rate transfer standard.
    9.2.1 Equipment required: Positive displacement standard volume 
meter traceable to the National Bureau of Standards (such as a Roots 
meter or equivalent), stop-watch, manometer, thermometer, and barometer.
    9.2.2 Connect the flow rate transfer standard to the inlet of the 
standard volume meter. Connect the manometer to measure the pressure at 
the inlet of the standard volume meter. Connect the orifice manometer to 
the pressure tap on the transfer standard. Connect a high-volume air 
pump (such as a high-volume sampler blower) to the outlet side of the 
standard volume meter. See Figure 3a.
    9.2.3 Check for leaks by temporarily clamping both manometer lines 
(to avoid fluid loss) and blocking the orifice with a large-diameter 
rubber stopper, wide cellophane tape, or other suitable means. Start the 
high-volume air pump and note any change in the standard volume meter 
reading. The reading should remain constant. If the reading changes, 
locate any leaks by listening for a whistling sound and/or retightening 
all connections, making sure that all gaskets are properly installed.
    9.2.4 After satisfactorily completing the leak check as described 
above, unclamp both manometer lines and zero both manometers.
    9.2.5 Achieve the appropriate flow rate through the system, either 
by means of the variable flow resistance in the transfer standard or by 
varying the voltage to the air pump. (Use of resistance plates as shown 
in Figure 1a is discouraged because the above leak check must be 
repeated each time a new resistance plate is installed.) At least five 
different but constant flow rates, evenly distributed, with at least 
three in the specified

[[Page 30]]

flow rate interval (1.1 to 1.7 m\3\/min [39-60 ft \3\/min]), are 
required.
    9.2.6 Measure and record the certification data on a form similar to 
the one illustrated in Figure 4 according to the following steps.
    9.2.7 Observe the barometric pressure and record as P1 
(item 8 in Figure 4).
    9.2.8 Read the ambient temperature in the vicinity of the standard 
volume meter and record it as T1 (item 9 in Figure 4).
    9.2.9 Start the blower motor, adjust the flow, and allow the system 
to run for at least 1 min for a constant motor speed to be attained.
    9.2.10 Observe the standard volume meter reading and simultaneously 
start a stopwatch. Record the initial meter reading (Vi) in 
column 1 of Figure 4.
    9.2.11 Maintain this constant flow rate until at least 3 
m3 of air have passed through the standard volume meter. 
Record the standard volume meter inlet pressure manometer reading as 
P (column 5 in Figure 4), and the orifice manometer reading as 
H (column 7 in Figure 4). Be sure to indicate the correct units 
of measurement.
    9.2.12 After at least 3 m3 of air have passed through the 
system, observe the standard volume meter reading while simultaneously 
stopping the stopwatch. Record the final meter reading (Vf) 
in column 2 and the elapsed time (t) in column 3 of Figure 4.
    9.2.13 Calculate the volume measured by the standard volume meter at 
meter conditions of temperature and pressures as 
Vm=Vf-Vi. Record in column 4 of Figure 
4.
    9.2.14 Correct this volume to standard volume (std m3) as 
follows:
[GRAPHIC] [TIFF OMITTED] TR31AU93.024

where:

Vstd = standard volume, std m3;
Vm = actual volume measured by the standard volume meter;
P1 = barometric pressure during calibration, mm Hg or kPa;
P = differential pressure at inlet to volume meter, mm Hg or 
kPa;
Pstd = 760 mm Hg or 101 kPa;
Tstd = 298 K;
T1 = ambient temperature during calibration, K.
Calculate the standard flow rate (std m3/min) as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.013

where:

Qstd = standard volumetric flow rate, std m3/min
t = elapsed time, minutes.

    Record Qstd to the nearest 0.01 std m3/min in 
column 6 of Figure 4.
    9.2.15 Repeat steps 9.2.9 through 9.2.14 for at least four 
additional constant flow rates, evenly spaced over the approximate range 
of 1.0 to 1.8 std m3/min (35-64 ft\3\/min).
    9.2.16 For each flow, compute

H (P1/Pstd)(298/
T1)

(column 7a of Figure 4) and plot these value against Qstd as 
shown in Figure 3a. Be sure to use consistent units (mm Hg or kPa) for 
barometric pressure. Draw the orifice transfer standard certification 
curve or calculate the linear least squares slope (m) and intercept (b) 
of the certification curve:

H (P1/Pstd)(298/
T1)

=mQstd+b. See Figures 3 and 4. A certification graph should 
be readable to 0.02 std m\3\/min.
    9.2.17 Recalibrate the transfer standard annually or as required by 
applicable quality control procedures. (See Reference 2.)
    9.3 Calibration of sampler flow indicator.

    Note: For samplers equipped with a flow controlling device, the flow 
controller must be disabled to allow flow changes during calibration of 
the sampler's flow indicator, or the alternate calibration of the flow 
controller given in 9.4 may be used. For samplers using an orifice-type 
flow indicator downstream of the motor, do not vary the flow rate by 
adjusting the voltage or power supplied to the sampler.

    9.3.1 A form similar to the one illustrated in Figure 5 should be 
used to record the calibration data.
    9.3.2 Connect the transfer standard to the inlet of the sampler. 
Connect the orifice manometer to the orifice pressure tap, as 
illustrated in Figure 3b. Make sure there are no leaks between the 
orifice unit and the sampler.
    9.3.3 Operate the sampler for at least 5 minutes to establish 
thermal equilibrium prior to the calibration.
    9.3.4 Measure and record the ambient temperature, T2, and 
the barometric pressure, P2, during calibration.
    9.3.5 Adjust the variable resistance or, if applicable, insert the 
appropriate resistance plate (or no plate) to achieve the desired flow 
rate.
    9.3.6 Let the sampler run for at least 2 min to re-establish the 
run-temperature conditions. Read and record the pressure drop across the 
orifice (H) and the sampler flow rate indication (I) in the 
appropriate columns of Figure 5.
    9.3.7 Calculate H(P2/
Pstd)(298/T2) and determine the flow rate at 
standard conditions (Qstd) either graphically from the 
certification curve or by calculating Qstd from the least 
square slope and intercept of the transfer standard's transposed 
certification curve: Qstd=1/m 
H(P2/Pstd)(298/T2)-b. 
Record the value of Qstd on Figure 5.

[[Page 31]]

    9.3.8 Repeat steps 9.3.5, 9.3.6, and 9.3.7 for several additional 
flow rates distributed over a range that includes 1.1 to 1.7 std 
m3/min.
    9.3.9 Determine the calibration curve by plotting values of the 
appropriate expression involving I, selected from table 1, against 
Qstd. The choice of expression from table 1 depends on the 
flow rate measurement device used (see Section 7.4.1) and also on 
whether the calibration curve is to incorporate geographic average 
barometric pressure (Pa) and seasonal average temperature 
(Ta) for the site to approximate actual pressure and 
temperature. Where Pa and Ta can be determined for 
a site for a seasonal period such that the actual barometric pressure 
and temperature at the site do not vary by more than 60 mm 
Hg (8 kPa) from Pa or 15  deg.C from Ta, 
respectively, then using Pa and Ta avoids the need 
for subsequent pressure and temperature calculation when the sampler is 
used. The geographic average barometric pressure (Pa) may be 
estimated from an altitude-pressure table or by making an (approximate) 
elevation correction of -26 mm Hg (-3.46 kPa) for each 305 m (1,000 ft) 
above sea level (760 mm Hg or 101 kPa). The seasonal average temperature 
(Ta) may be estimated from weather station or other records. 
Be sure to use consistent units (mm Hg or kPa) for barometric pressure.
    9.3.10 Draw the sampler calibration curve or calculate the linear 
least squares slope (m), intercept (b), and correlation coefficient of 
the calibration curve: [Expression from table 1]= mQstd+b. 
See Figures 3 and 5. Calibration curves should be readable to 0.02 std 
m3/min.
    9.3.11 For a sampler equipped with a flow controller, the flow 
controlling mechanism should be re-enabled and set to a flow near the 
lower flow limit to allow maximum control range. The sample flow rate 
should be verified at this time with a clean filter installed. Then add 
two or more filters to the sampler to see if the flow controller 
maintains a constant flow; this is particularly important at high 
altitudes where the range of the flow controller may be reduced.
    9.4 Alternate calibration of flow-controlled samplers. A flow-
controlled sampler may be calibrated solely at its controlled flow rate, 
provided that previous operating history of the sampler demonstrates 
that the flow rate is stable and reliable. In this case, the flow 
indicator may remain uncalibrated but should be used to indicate any 
relative change between initial and final flows, and the sampler should 
be recalibrated more often to minimize potential loss of samples because 
of controller malfunction.
    9.4.1 Set the flow controller for a flow near the lower limit of the 
flow range to allow maximum control range.
    9.4.2 Install a clean filter in the sampler and carry out steps 
9.3.2, 9.3.3, 9.3.4, 9.3.6, and 9.3.7.
    9.4.3 Following calibration, add one or two additional clean filters 
to the sampler, reconnect the transfer standard, and operate the sampler 
to verify that the controller maintains the same calibrated flow rate; 
this is particularly important at high altitudes where the flow control 
range may be reduced.



[[Page 32]]




    10.0 Calculations of TSP Concentration.
    10.1 Determine the average sampler flow rate during the sampling 
period according to either 10.1.1 or 10.1.2 below.
    10.1.1 For a sampler without a continuous flow recorder, determine 
the appropriate expression to be used from table 2 corresponding to the 
one from table 1 used in step 9.3.9. Using this appropriate expression, 
determine Qstd for the initial flow rate from the sampler 
calibration curve, either graphically or from the transposed regression 
equation:

Qstd =
1/m ([Appropriate expression from table 2]-b)

Similarly, determine Qstd from the final flow reading, and 
calculate the average flow Qstd as one-half the sum of the 
initial and final flow rates.
    10.1.2 For a sampler with a continuous flow recorder, determine the 
average flow rate device reading, I, for the period. Determine the 
appropriate expression from table 2 corresponding to the one from table 
1 used in step 9.3.9. Then using this expression and the average flow 
rate reading, determine Qstd from the sampler calibration 
curve, either graphically or from the transposed regression equation:

Qstd =

1/m ([Appropriate expression from table 2]-b)
    If the trace shows substantial flow change during the sampling 
period, greater accuracy may be achieved by dividing the sampling period 
into intervals and calculating an average reading before determining 
Qstd.
    10.2 Calculate the total air volume sampled as:

V-Qstd x t

where:

V = total air volume sampled, in standard volume units, std m\3\/;
Qstd = average standard flow rate, std m\3\/min;
t = sampling time, min.

    10.3 Calculate and report the particulate matter concentration as:
    [GRAPHIC] [TIFF OMITTED] TR31AU93.025
    
where:

TSP = mass concentration of total suspended particulate matter, 
g/std m\3\;
Wi = initial weight of clean filter, g;
Wf = final weight of exposed filter, g;
V = air volume sampled, converted to standard conditions, std m\3\,
10\6\ = conversion of g to g.

    10.4 If desired, the actual particulate matter concentration (see 
Section 2.2) can be calculated as follows:

(TSP)a=TSP (P3/Pstd)(298/T3)

where:

(TSP)a = actual concentration at field conditions, 
g/m\3\;

[[Page 33]]

TSP = concentration at standard conditions, g/std m\3\;
P3 = average barometric pressure during sampling period, mm 
Hg;
Pstd = 760 mn Hg (or 101 kPa);
T3 = average ambient temperature during sampling period, K.

    11.0 References.
    1. Quality Assurance Handbook for Air Pollution Measurement Systems, 
Volume I, Principles. EPA-600/9-76-005, U.S. Environmental Protection 
Agency, Research Triangle Park, NC 27711, 1976.
    2. Quality Assurance Handbook for Air Pollution Measurement Systems, 
Volume II, Ambient Air Specific Methods. EPA-600/4-77-027a, U.S. 
Environmental Protection Agency, Research Triangle Park, NC 27711, 1977.
    3. Wedding, J. B., A. R. McFarland, and J. E. Cernak. Large Particle 
Collection Characteristics of Ambient Aerosol Samplers. Environ. Sci. 
Technol. 11:387-390, 1977.
    4. McKee, H. C., et al. Collaborative Testing of Methods to Measure 
Air Pollutants, I. The High-Volume Method for Suspended Particulate 
Matter. J. Air Poll. Cont. Assoc., 22 (342), 1972.
    5. Clement, R. E., and F. W. Karasek. Sample Composition Changes in 
Sampling and Analysis of Organic Compounds in Aerosols. The Intern. J. 
Environ. Anal. Chem., 7:109, 1979.
    6. Lee, R. E., Jr., and J. Wagman. A Sampling Anomaly in the 
Determination of Atmospheric Sulfuric Concentration. Am. Ind. Hygiene 
Assoc. J., 27:266, 1966.
    7. Appel, B. R., et al. Interference Effects in Sampling Particulate 
Nitrate in Ambient Air. Atmospheric Environment, 13:319, 1979.
    8. Tierney, G. P., and W. D. Conner. Hygroscopic Effects on Weight 
Determinations of Particulates Collected on Glass-Fiber Filters. Am. 
Ind. Hygiene Assoc. J., 28:363, 1967.
    9. Chahal, H. S., and D. J. Romano. High-Volume Sampling Effect of 
Windborne Particulate Matter Deposited During Idle Periods. J. Air Poll. 
Cont. Assoc., Vol. 26 (885), 1976.
    10. Patterson, R. K. Aerosol Contamination from High-Volume Sampler 
Exhaust. J. Air Poll. Cont. Assoc., Vol. 30 (169), 1980.
    11. EPA Test Procedures for Determining pH and Integrity of High-
Volume Air Filters. QAD/M-80.01. Available from the Methods 
Standardization Branch, Quality Assurance Division, Environmental 
Monitoring Systems Laboratory (MD-77), U.S. Environmental Protection 
Agency, Research Triangle Park, NC 27711, 1980.
    12. Smith, F., P. S. Wohlschlegel, R. S. C. Rogers, and D. J. 
Mulligan. Investigation of Flow Rate Calibration Procedures Associated 
with the High-Volume Method for Determination of Suspended Particulates. 
EPA-600/4-78-047, U.S. Environmental Protection Agency, Research 
Triangle Park, NC, June 1978.



[[Page 34]]





[[Page 35]]





[[Page 36]]





[[Page 37]]




[47 FR 54912, Dec. 6, 1982; 48 FR 17355, Apr. 22, 1983]

 Appendix C to Part 50--Measurement Principle and Calibration Procedure 
for the Measurement of Carbon Monoxide in the Atmosphere (Non-Dispersive 
                          Infrared Photometry)

                          Measurement Principle

    1. Measurements are based on the absorption of infrared radiation by 
carbon monoxide (CO) in a non-dispersive photometer. Infrared energy 
from a source is passed through a cell containing the gas sample to be 
analyzed, and the quantitative absorption of energy by CO in the sample 
cell is measured by a suitable detector. The photometer is sensitized to 
CO by employing CO gas in either the detector or in a filter cell in the 
optical path, thereby limiting the measured absorption to one or more of 
the characteristic wavelengths at which CO strongly absorbs. Optical 
filters or other means may

[[Page 38]]

also be used to limit sensitivity of the photometer to a narrow band of 
interest. Various schemes may be used to provide a suitable zero 
reference for the photometer. The measured absorption is converted to an 
electrical output signal, which is related to the concentration of CO in 
the measurement cell.
    2. An analyzer based on this principle will be considered a 
reference method only if it has been designated as a reference method in 
accordance with part 53 of this chapter.
    3. Sampling considerations.
    The use of a particle filter on the sample inlet line of an NDIR CO 
analyzer is optional and left to the discretion of the user or the 
manufacturer. Use of filter should depend on the analyzer's 
susceptibility to interference, malfunction, or damage due to particles.

                          Calibration Procedure

    1. Principle. Either of two methods may be used for dynamic 
multipoint calibration of CO analyzers:
    (1) One method uses a single certified standard cylinder of CO, 
diluted as necessary with zero air, to obtain the various calibration 
concentrations needed.
    (2) The other method uses individual certified standard cylinders of 
CO for each concentration needed. Additional information on calibration 
may be found in Section 2.0.9 of Reference 1.
    2. Apparatus. The major components and typical configurations of the 
calibration systems for the two calibration methods are shown in Figures 
1 and 2.
    2.1 Flow controller(s). Device capable of adjusting and regulating 
flow rates. Flow rates for the dilution method (Figure 1) must be 
regulated to  1%.
    2.2 Flow meter(s). Calibrated flow meter capable of measuring and 
monitoring flow rates. Flow rates for the dilution method (Figure 1) 
must be measured with an accuracy of  2% of the measured 
value.
    2.3 Pressure regulator(s) for standard CO cylinder(s). Regulator 
must have nonreactive diaphragm and internal parts and a suitable 
delivery pressure.
    2.4 Mixing chamber. A chamber designed to provide thorough mixing of 
CO and diluent air for the dilution method.
    2.5 Output manifold. The output manifold should be of sufficient 
diameter to insure an insignificant pressure drop at the analyzer 
connection. The system must have a vent designed to insure atmospheric 
pressure at the manifold and to prevent ambient air from entering the 
manifold.
    3. Reagents.
    3.1 CO concentration standard(s). Cylinder(s) of CO in air 
containing appropriate concentrations(s) of CO suitable for the selected 
operating range of the analyzer under calibration; CO standards for the 
dilution method may be contained in a nitrogen matrix if the zero air 
dilution ratio is not less than 100:1. The assay of the cylinder(s) must 
be traceable either to a National Bureau of Standards (NBS) CO in air 
Standard Reference Material (SRM) or to an NBS/EPA-approved commercially 
available Certified Reference Material (CRM). CRM's are described in 
Reference 2, and a list of CRM sources is available from the address 
shown for Reference 2. A recommended protocol for certifying CO gas 
cylinders against either a CO SRM or a CRM is given in Reference 1. CO 
gas cylinders should be recertified on a regular basis as determined by 
the local quality control program.
    3.2 Dilution gas (zero air). Air, free of contaminants which will 
cause a detectable response on the CO analyzer. The zero air should 
contain <0.1 ppm CO. A procedure for generating zero air is given in 
Reference 1.
    4. Procedure Using Dynamic Dilution Method.
    4.1 Assemble a dynamic calibration system such as the one shown in 
Figure 1. All calibration gases including zero air must be introduced 
into the sample inlet of the analyzer system. For specific operating 
instructions refer to the manufacturer's manual.
    4.2 Insure that all flowmeters are properly calibrated, under the 
conditions of use, if appropriate, against an authoritative standard 
such as a soap-bubble meter or wet-test meter. All volumetric flowrates 
should be corrected to 25  deg.C and 760 mm Hg (101 kPa). A discussion 
on calibration of flowmeters is given in Reference 1.
    4.3 Select the operating range of the CO analyzer to be calibrated.
    4.4 Connect the signal output of the CO analyzer to the input of the 
strip chart recorder or other data collection device. All adjustments to 
the analyzer should be based on the appropriate strip chart or data 
device readings. References to analyzer responses in the procedure given 
below refer to recorder or data device responses.
    4.5 Adjust the calibration system to deliver zero air to the output 
manifold. The total air flow must exceed the total demand of the 
analyzer(s) connected to the output manifold to insure that no ambient 
air is pulled into the manifold vent. Allow the analyzer to sample zero 
air until a stable respose is obtained. After the response has 
stabilized, adjust the analyzer zero control. Offsetting the analyzer 
zero adjustments to +5 percent of scale is recommended to facilitate 
observing negative zero drift. Record the stable zero air response as 
ZCO.
    4.6 Adjust the zero air flow and the CO flow from the standard CO 
cylinder to provide a diluted CO concentration of approximately 80 
percent of the upper range limit (URL) of the operating range of the 
analyzer. The total air flow must exceed the total demand of the 
analyzer(s) connected to the output manifold to insure that no ambient 
air is

[[Page 39]]

pulled into the manifold vent. The exact CO concentration is calculated 
from:
[GRAPHIC] [TIFF OMITTED] TR31AU93.026

where:

[CO]OUT = diluted CO concentration at the output manifold, 
ppm;
[CO]STD = concentration of the undiluted CO standard, ppm;
FCO = flow rate of the CO standard corrected to 25  deg.C and 
760 mm Hg, (101 kPa), L/min; and
FD = flow rate of the dilution air corrected to 25  deg.C and 
760 mm Hg, (101 kPa), L/min.

    Sample this CO concentration until a stable response is obtained. 
Adjust the analyzer span control to obtain a recorder response as 
indicated below:

Recorder response (percent scale) =

[GRAPHIC] [TIFF OMITTED] TR31AU93.027

where:

URL = nominal upper range limit of the analyzer's operating range, and
ZCO = analyzer response to zero air, % scale.

    If substantial adjustment of the analyzer span control is required, 
it may be necessary to recheck the zero and span adjustments by 
repeating Steps 4.5 and 4.6. Record the CO concentration and the 
analyzer's response. 4.7 Generate several additional concentrations (at 
least three evenly spaced points across the remaining scale are 
suggested to verify linearity) by decreasing FCO or 
increasing FD. Be sure the total flow exceeds the analyzer's 
total flow demand. For each concentration generated, calculate the exact 
CO concentration using Equation (1). Record the concentration and the 
analyzer's response for each concentration. Plot the analyzer responses 
versus the corresponding CO concentrations and draw or calculate the 
calibration curve.
    5. Procedure Using Multiple Cylinder Method. Use the procedure for 
the dynamic dilution method with the following changes:
    5.1 Use a multi-cylinder system such as the typical one shown in 
Figure 2.
    5.2 The flowmeter need not be accurately calibrated, provided the 
flow in the output manifold exceeds the analyzer's flow demand.
    5.3 The various CO calibration concentrations required in Steps 4.6 
and 4.7 are obtained without dilution by selecting the appropriate 
certified standard cylinder.

                               References

    1. Quality Assurance Handbook for Air Pollution Measurement Systems, 
Volume II--Ambient Air Specific Methods, EPA-600/4-77-027a, U.S. 
Environmental Protection Agency, Environmental Monitoring Systems 
Laboratory, Research Triangle Park, NC 27711, 1977.
    2. A procedure for Establishing Traceability of Gas Mixtures to 
Certain National Bureau of Standards Standard Reference Materials. EPA-
600/7-81-010, U.S. Environmental Protection Agency, Environmental 
Monitoring Systems Laboratory (MD-77), Research Triangle Park, NC 27711, 
January 1981.

[[Page 40]]




[[Page 41]]




[47 FR 54922, Dec. 6, 1982; 48 FR 17355, Apr. 22, 1983]

[[Page 42]]

 Appendix D to Part 50--Measurement Principle and Calibration Procedure 
             for the Measurement of Ozone in the Atmosphere

                          measurement principle

    1. Ambient air and ethylene are delivered simultaneously to a mixing 
zone where the ozone in the air reacts with the ethylene to emit light, 
which is detected by a photomultiplier tube. The resulting photocurrent 
is amplified and is either read directly or displayed on a recorder.
    2. An analyzer based on this principle will be considered a 
reference method only if it has been designated as a reference method in 
accordance with part 53 of this chapter and calibrated as follows:

                          calibration procedure

    1. Principle. The calibration procedure is based on the photometric 
assay of ozone (O3) concentrations in a dynamic flow system. 
The concentration of O3 in an absorption cell is determined 
from a measurement of the amount of 254 nm light absorbed by the sample. 
This determination requires knowledge of (1) the absorption coefficient 
() of O3 at 254 nm, (2) the optical path length (l) 
through the sample, (3) the transmittance of the sample at a wavelength 
of 254 nm, and (4) the temperature (T) and pressure (P) of the sample. 
The transmittance is defined as the ratio I/I0, where I is 
the intensity of light which passes through the cell and is sensed by 
the detector when the cell contains an O3 sample, and I0 
is the intensity of light which passes through the cell and is sensed by 
the detector when the cell contains zero air. It is assumed that all 
conditions of the system, except for the contents of the absorption 
cell, are identical during measurement of I and I0. The 
quantities defined above are related by the Beer-Lambert absorption law,
[GRAPHIC] [TIFF OMITTED] TR31AU93.028

where:

 = absorption coefficient of O3 at 254 
nm=308plus-minus4 atm-1 cm-1 at 0 
deg.C and 760 torr. (1, 2, 3, 4, 5, 
6, 7)
c = O3 concentration in atmospheres
l = optical path length in cm

    In practice, a stable O3 generator is used to produce 
O3 concentrations over the required range. Each O3 
concentration is determined from the measurement of the transmittance 
(I/I0) of the sample at 254 nm with a photometer of path 
length l and calculated from the equation,
[GRAPHIC] [TIFF OMITTED] TR31AU93.029

The calculated O3 concentrations must be corrected for 
O3 losses which may occur in the photometer and for the 
temperature and pressure of the sample.
    2. Applicability. This procedure is applicable to the calibration of 
ambient air O3 analyzers, either directly or by means of a 
transfer standard certified by this procedure. Transfer standards must 
meet the requirements and specifications set forth in Reference 8.
    3. Apparatus. A complete UV calibration system consists of an ozone 
generator, an output port or manifold, a photometer, an appropriate 
source of zero air, and other components as necessary. The configuration 
must provide a stable ozone concentration at the system output and allow 
the photometer to accurately assay the output concentration to the 
precision specified for the photometer (3.1). Figure 1 shows a commonly 
used configuration and serves to illustrate the calibration procedure 
which follows. Other configurations may require appropriate variations 
in the procedural steps. All connections between components in the 
calibration system downstream of the O3 generator should be 
of glass, Teflon, or other relatively inert materials. Additional 
information regarding the assembly of a UV photometric calibration 
apparatus is given in Reference 9. For certification of transfer 
standards which provide their own source of O3, the transfer 
standard may replace the O3 generator and possibly other 
components shown in Figure 1; see Reference 8 for guidance.
    3.1 UV photometer. The photometer consists of a low-pressure mercury 
discharge lamp, (optional) collimation optics, an absorption cell, a 
detector, and signal-processing electronics, as illustrated in Figure 1. 
It must be capable of measuring the transmittance, I/I0, at a 
wavelength of 254 nm with sufficient precision such that the standard 
deviation of the concentration measurements does not exceed the greater 
of 0.005 ppm or 3% of the concentration. Because the low-pressure 
mercury lamp radiates at several wavelengths, the photometer must 
incorporate suitable means to assure that no O3 is generated 
in the cell by the lamp, and that at least 99.5% of the radiation sensed 
by the detector is 254 nm radiation. (This can be readily achieved by 
prudent selection of optical filter and detector response 
characteristics.) The length of the light path through the absorption 
cell must be known with an accuracy of at least 99.5%. In addition, the 
cell and associated plumbing must be designed to

[[Page 43]]

minimize loss of O3 from contact with cell walls and gas 
handling components. See Reference 9 for additional information.
    3.2 Air flow controllers. Devices capable of regulating air flows as 
necessary to meet the output stability and photometer precision 
requirements.
    3.3 Ozone generator. Device capable of generating stable levels of 
O3 over the required concentration range.
    3.4 Output manifold. The output manifold should be constructed of 
glass, Teflon, or other relatively inert material, and should be of 
sufficient diameter to insure a negligible pressure drop at the 
photometer connection and other output ports. The system must have a 
vent designed to insure atmospheric pressure in the manifold and to 
prevent ambient air from entering the manifold.
    3.5 Two-way valve. Manual or automatic valve, or other means to 
switch the photometer flow between zero air and the O3 
concentration.
    3.6 Temperature indicator. Accurate to plus-minus1 
deg.C.
    3.7 Barometer or pressure indicator. Accurate to 
plus-minus2 torr.
    4. Reagents.
    4.1 Zero air. The zero air must be free of contaminants which would 
cause a detectable response from the O3 analyzer, and it 
should be free of NO, C2 H4, and other species 
which react with O3. A procedure for generating suitable zero 
air is given in Reference 9. As shown in Figure 1, the zero air supplied 
to the photometer cell for the I0 reference measurement must 
be derived from the same source as the zero air used for generation of 
the ozone concentration to be assayed (I measurement). When using the 
photometer to certify a transfer standard having its own source of 
ozone, see Reference 8 for guidance on meeting this requirement.
    5. Procedure.
    5.1 General operation. The calibration photometer must be dedicated 
exclusively to use as a calibration standard. It should always be used 
with clean, filtered calibration gases, and never used for ambient air 
sampling. Consideration should be given to locating the calibration 
photometer in a clean laboratory where it can be stationary, protected 
from physical shock, operated by a responsible analyst, and used as a 
common standard for all field calibrations via transfer standards.
    5.2 Preparation. Proper operation of the photometer is of critical 
importance to the accuracy of this procedure. The following steps will 
help to verify proper operation. The steps are not necessarily required 
prior to each use of the photometer. Upon initial operation of the 
photometer, these steps should be carried out frequently, with all 
quantitative results or indications recorded in a chronological record 
either in tabular form or plotted on a graphical chart. As the 
performance and stability record of the photometer is established, the 
frequency of these steps may be reduced consistent with the documented 
stability of the photometer.
    5.2.1 Instruction manual: Carry out all set up and adjustment 
procedures or checks as described in the operation or instruction manual 
associated with the photometer.
    5.2.2 System check: Check the photometer system for integrity, 
leaks, cleanliness, proper flowrates, etc. Service or replace filters 
and zero air scrubbers or other consumable materials, as necessary.
    5.2.3 Linearity: Verify that the photometer manufacturer has 
adequately established that the linearity error of the photometer is 
less than 3%, or test the linearity by dilution as follows: Generate and 
assay an O3 concentration near the upper range limit of the 
system (0.5 or 1.0 ppm), then accurately dilute that concentration with 
zero air and reassay it. Repeat at several different dilution ratios. 
Compare the assay of the original concentration with the assay of the 
diluted concentration divided by the dilution ratio, as follows
[GRAPHIC] [TIFF OMITTED] TR31AU93.030

where:

E = linearity error, percent
A1 = assay of the original concentration
A2 = assay of the diluted concentration
R = dilution ratio = flow of original concentration divided by the total 
flow

    The linearity error must be less than 5%. Since the accuracy of the 
measured flow-rates will affect the linearity error as measured this 
way, the test is not necessarily conclusive. Additional information on 
verifying linearity is contained in Reference 9.
    5.2.4 Intercomparison: When possible, the photometer should be 
occasionally intercompared, either directly or via transfer standards, 
with calibration photometers used by other agencies or laboratories.
    5.2.5 Ozone losses: Some portion of the O3 may be lost 
upon contact with the photometer cell walls and gas handling components. 
The magnitude of this loss must be determined and used to correct the 
calculated O3 concentration. This loss must not exceed 5%. 
Some guidelines for quantitatively determining this loss are discussed 
in Reference 9.
    5.3 Assay of O3 concentrations.
    5.3.1 Allow the photometer system to warm up and stabilizer.
    5.3.2 Verify that the flowrate through the photometer absorption 
cell, F allows the cell to be flushed in a reasonably short period of 
time (2 liter/min is a typical flow). The precision of the measurements 
is inversely related to the time required for flushing, since the 
photometer drift error increases with time.

[[Page 44]]

    5.3.3 Insure that the flowrate into the output manifold is at least 
1 liter/min greater than the total flowrate required by the photometer 
and any other flow demand connected to the manifold.
    5.3.4 Insure that the flowrate of zero air, Fz, is at 
least 1 liter/min greater than the flowrate required by the photometer.
    5.3.5 With zero air flowing in the output manifold, actuate the two-
way valve to allow the photometer to sample first the manifold zero air, 
then Fz. The two photometer readings must be equal 
(I=Io).
    Note: In some commercially available photometers, the operation of 
the two-way valve and various other operations in section 5.3 may be 
carried out automatically by the photometer.
    5.3.6 Adjust the O3 generator to produce an O3 
concentration as needed.
    5.3.7 Actuate the two-way valve to allow the photometer to sample 
zero air until the absorption cell is thoroughly flushed and record the 
stable measured value of Io.
    5.3.8 Actuate the two-way valve to allow the photometer to sample 
the ozone concentration until the absorption cell is thoroughly flushed 
and record the stable measured value of I.
    5.3.9 Record the temperature and pressure of the sample in the 
photometer absorption cell. (See Reference 9 for guidance.)
    5.3.10 Calculate the O3 concentration from equation 4. An 
average of several determinations will provide better precision.
[GRAPHIC] [TIFF OMITTED] TR31AU93.032

where:

[O3]OUT = O3 concentration, ppm
 = absorption coefficient of O3 at 254 nm=308 
atm-1 cm-1 at 0  deg.C and 760 torr
l = optical path length, cm
T = sample temperature, K
P = sample pressure, torr
L = correction factor for O3 losses from 5.2.5=(1-fraction 
O3 lost).

    Note: Some commercial photometers may automatically evaluate all or 
part of equation 4. It is the operator's responsibility to verify that 
all of the information required for equation 4 is obtained, either 
automatically by the photometer or manually. For ``automatic'' 
photometers which evaluate the first term of equation 4 based on a 
linear approximation, a manual correction may be required, particularly 
at higher O3 levels. See the photometer instruction manual 
and Reference 9 for guidance.
    5.3.11 Obtain additional O3 concentration standards as 
necessary by repeating steps 5.3.6 to 5.3.10 or by Option 1.
    5.4 Certification of transfer standards. A transfer standard is 
certified by relating the output of the transfer standard to one or more 
ozone standards as determined according to section 5.3. The exact 
procedure varies depending on the nature and design of the transfer 
standard. Consult Reference 8 for guidance.
    5.5 Calibration of ozone analyzers. Ozone analyzers are calibrated 
as follows, using ozone standards obtained directly according to section 
5.3 or by means of a certified transfer standard.
    5.5.1 Allow sufficient time for the O3 analyzer and the 
photometer or transfer standard to warmup and stabilize.
    5.5.2 Allow the O3 analyzer to sample zero air until a 
stable response is obtained and adjust the O3 analyzer's zero 
control. Offsetting the analyzer's zero adjustment to +5% of scale is 
recommended to facilitate observing negative zero drift. Record the 
stable zero air response as ``Z''.
    5.5.3 Generate an O3 concentration standard of 
approximately 80% of the desired upper range limit (URL) of the O3 
analyzer. Allow the O3 analyzer to sample this O3 
concentration standard until a stable response is obtained.
    5.5.4 Adjust the O3 analyzer's span control to obtain a 
convenient recorder response as indicated below:
    recorder response (%scale) =
    [GRAPHIC] [TIFF OMITTED] TR31AU93.033
    
where:

URL = upper range limit of the O3 analyzer, ppm
Z = recorder response with zero air, % scale

    Record the O3 concentration and the corresponding 
analyzer response. If substantial adjustment of the span control is 
necessary, recheck the zero and span adjustments by repeating steps 
5.5.2 to 5.5.4.
    5.5.5 Generate several other O3 concentration standards 
(at least 5 others are recommended) over the scale range of the O3 
analyzer by adjusting the O3 source or by Option 1. For each 
O3 concentration standard, record the O3 and the 
corresponding analyzer response.
    5.5.6 Plot the O3 analyzer responses versus the 
corresponding O3 concentrations and draw the O3 
analyzer's calibration curve or calculate the appropriate response 
factor.
    5.5.7 Option 1: The various O3 concentrations required in 
steps 5.3.11 and 5.5.5 may be obtained by dilution of the O3 
concentration generated in steps 5.3.6 and 5.5.3. With this option, 
accurate flow measurements are required. The dynamic calibration system 
may be modified as shown in Figure 2 to allow for dilution air to be 
metered in downstream of the O3 generator. A mixing chamber 
between the O3 generator and the output manifold is also 
required. The flowrate through the O3 generator 
(Fo) and the dilution air flowrate

[[Page 45]]

(FD) are measured with a reliable flow or volume standard 
traceable to NBS. Each O3 concentration generated by dilution 
is calculated from:
[GRAPHIC] [TIFF OMITTED] TR31AU93.031

where:

[O3]'OUT = diluted O3 concentration, 
ppm
F0 = flowrate through the O3 generator, liter/min
FD = diluent air flowrate, liter/min

                               References

    1. E.C.Y. Inn and Y. Tanaka, ``Absorption coefficient of Ozone in 
the Ultraviolet and Visible Regions'', J. Opt. Soc. Am., 43, 870 (1953).
    2. A. G. Hearn, ``Absorption of Ozone in the Ultraviolet and Visible 
Regions of the Spectrum'', Proc. Phys. Soc. (London), 78, 932 (1961).
    3. W. B. DeMore and O. Raper, ``Hartley Band Extinction Coefficients 
of Ozone in the Gas Phase and in Liquid Nitrogen, Carbon Monoxide, and 
Argon'', J. Phys. Chem., 68, 412 (1964).
    4. M. Griggs, ``Absorption Coefficients of Ozone in the Ultraviolet 
and Visible Regions'', J. Chem. Phys., 49, 857 (1968).
    5. K. H. Becker, U. Schurath, and H. Seitz, ``Ozone Olefin Reactions 
in the Gas Phase. 1. Rate Constants and Activation Energies'', Int'l 
Jour. of Chem. Kinetics, VI, 725 (1974).
    6. M. A. A. Clyne and J. A. Coxom, ``Kinetic Studies of Oxy-halogen 
Radical Systems'', Proc. Roy. Soc., A303, 207 (1968).
    7. J. W. Simons, R. J. Paur, H. A. Webster, and E. J. Bair, ``Ozone 
Ultraviolet Photolysis. VI. The Ultraviolet Spectrum'', J. Chem. Phys., 
59, 1203 (1973).
    8. Transfer Standards for Calibration of Ambient Air Monitoring 
Analyzers for Ozone, EPA publication number EPA-600/4-79-056, EPA, 
National Exposure Research Laboratory, Department E, (MD-77B), Research 
Triangle Park, NC 27711.
    9. Technical Assistance Document for the Calibration of Ambient 
Ozone Monitors, EPA publication number EPA-600/4-79-057, EPA, National 
Exposure Research Laboratory, Department E, (MD-77B), Research Triangle 
Park, NC 27711.

[[Page 46]]




[[Page 47]]



[44 FR 8224, Feb. 8, 1979, as amended at 62 FR 38895, July 18, 1997]

                    Appendix E to Part 50 [Reserved]

 Appendix F to Part 50--Measurement Principle and Calibration Procedure 
  for the Measurement of Nitrogen Dioxide in the Atmosphere (Gas Phase 
                           Chemiluminescence)

                       Principle and Applicability

    1. Atmospheric concentrations of nitrogen dioxide (NO2) 
are measured indirectly by photometrically measuring the light 
intensity, at wavelengths greater than 600 nanometers, resulting from 
the chemiluminescent reaction of nitric oxide (NO) with ozone 
(O3). (1,2,3) NO2 is first quantitatively reduced 
to NO(4,5,6) by means of a converter. NO, which commonly exists in 
ambient air together with NO2, passes through the converter 
unchanged causing a resultant total NOX concentration equal 
to NO+NO2. A sample of the input air is also measured without 
having passed through the converted. This latter NO measurement is 
subtracted from the former measurement (NO+NO2) to yield the 
final NO2 measurement. The NO and NO+NO2 
measurements may be made concurrently with dual systems, or cyclically 
with the same system provided the cycle time does not exceed 1 minute.
    2. Sampling considerations.
    2.1 Chemiluminescence NO/NOX/NO2 analyzers 
will respond to other nitrogen containing compounds, such as 
peroxyacetyl nitrate (PAN), which might be reduced to NO in the thermal 
converter. (7) Atmospheric concentrations of these potential 
interferences are generally low relative to NO2 and valid 
NO2 measurements may be obtained. In certain geographical 
areas, where the concentration of these potential interferences is known 
or suspected to be high relative to NO2, the use of an 
equivalent method for the measurement of NO2 is recommended.
    2.2 The use of integrating flasks on the sample inlet line of 
chemiluminescence NO/NOX/NO2 analyzers is optional 
and left to couraged. The sample residence time between the sampling 
point and the analyzer should be kept to a minimum to avoid erroneous 
NO2 measurements resulting from the reaction of ambient 
levels of NO and O3 in the sampling system.
    2.3 The use of particulate filters on the sample inlet line of 
chemiluminescence NO/NOX/NO2 analyzers is optional 
and left to the discretion of the user or the manufacturer.
Use of the filter should depend on the analyzer's susceptibility to 
interference, malfunction, or damage due to particulates. Users are 
cautioned that particulate matter concentrated on a filter may cause 
erroneous NO2 measurements and therefore filters should be 
changed frequently.
    3. An analyzer based on this principle will be considered a 
reference method only if it has been designated as a reference method in 
accordance with part 53 of this chapter.

                               Calibration

    1. Alternative A--Gas phase titration (GPT) of an NO standard with 
O3.
    Major equipment required: Stable O3 generator. 
Chemiluminescence NO/NOX/NO2 analyzer with strip 
chart recorder(s). NO concentration standard.
    1.1 Principle. This calibration technique is based upon the rapid 
gas phase reaction between NO and O3 to produce 
stoichiometric quantities of NO2 in accordance with the 
following equation: (8)
[GRAPHIC] [TIFF OMITTED] TC08NO91.075

The quantitative nature of this reaction is such that when the NO 
concentration is known, the concentration of NO2 can be 
determined. Ozone is added to excess NO in a dynamic calibration system, 
and the NO channel of the chemiluminescence NO/NOX/NO2 
analyzer is used as an indicator of changes in NO concentration. Upon 
the addition of O3, the decrease in NO concentration observed 
on the calibrated NO channel is equivalent to the concentration of 
NO2 produced. The amount of NO2 generated may be 
varied by adding variable amounts of O3 from a stable 
uncalibrated O3 generator. (9)
    1.2 Apparatus. Figure 1, a schematic of a typical GPT apparatus, 
shows the suggested configuration of the components listed below. All 
connections between components in the calibration system downstream from 
the O3 generator should be of glass, Teflon, or 
other non-reactive material.
    1.2.1 Air flow controllers. Devices capable of maintaining constant 
air flows within plus-minus2% of the required flowrate.
    1.2.2 NO flow controller. A device capable of maintaining constant 
NO flows within plus-minus2% of the required flowrate. 
Component parts in contact with the NO should be of a non-reactive 
material.
    1.2.3 Air flowmeters. Calibrated flowmeters capable of measuring and 
monitoring air flowrates with an accuracy of plus-minus2% of 
the measured flowrate.
    1.2.4 NO flowmeter. A calibrated flowmeter capable of measuring and 
monitoring NO flowrates with an accuracy of plus-minus2% of 
the measured flowrate. (Rotameters have been reported to operate 
unreliably when measuring low NO flows and are not recommended.)
    1.2.5 Pressure regulator for standard NO cylinder. This regulator 
must have a nonreactive diaphragm and internal parts and a suitable 
delivery pressure.

[[Page 48]]

    1.2.6 Ozone generator. The generator must be capable of generating 
sufficient and stable levels of O3 for reaction with NO to 
generate NO2 concentrations in the range required. Ozone 
generators of the electric discharge type may produce NO and NO2 
and are not recommended.
    1.2.7 Valve. A valve may be used as shown in Figure 1 to divert the 
NO flow when zero air is required at the manifold. The valve should be 
constructed of glass, Teflon, or other nonreactive material.
    1.2.8 Reaction chamber. A chamber, constructed of glass, 
Teflon, or other nonreactive material, for the quantitative 
reaction of O3 with excess NO. The chamber should be of 
sufficient volume (VRC) such that the residence time 
(tR) meets the requirements specified in 1.4. For practical 
reasons, tR should be less than 2 minutes.
    1.2.9 Mixing chamber. A chamber constructed of glass, 
Teflon, or other nonreactive material and designed to 
provide thorough mixing of reaction products and diluent air. The 
residence time is not critical when the dynamic parameter specification 
given in 1.4 is met.
    1.2.10 Output manifold. The output manifold should be constructed of 
glass, Teflon, or other non-reactive material and should be 
of sufficient diameter to insure an insignificant pressure drop at the 
analyzer connection. The system must have a vent designed to insure 
atmospheric pressure at the manifold and to prevent ambient air from 
entering the manifold.
    1.3 Reagents.
    1.3.1 NO concentration standard. Gas cylinder standard containing 50 
to 100 ppm NO in N2 with less than 1 ppm NO2. This 
standard must be traceable to a National Bureau of Standards (NBS) NO in 
N2 Standard Reference Material (SRM 1683 or SRM 1684), an NBS 
NO2 Standard Reference Material (SRM 1629), or an NBS/EPA-
approved commercially available Certified Reference Material (CRM). 
CRM's are described in Reference 14, and a list of CRM sources is 
available from the address shown for Reference 14. A recommended 
protocol for certifying NO gas cylinders against either an NO SRM or CRM 
is given in section 2.0.7 of Reference 15. Reference 13 gives procedures 
for certifying an NO gas cylinder against an NBS NO2 SRM and 
for determining the amount of NO2 impurity in an NO cylinder.
    1.3.2 Zero air. Air, free of contaminants which will cause a 
detectable response on the NO/NOX/NO2 analyzer or 
which might react with either NO, O3, or NO2 in 
the gas phase titration. A procedure for generating zero air is given in 
reference 13.
    1.4 Dynamic parameter specification.
    1.4.1 The O3 generator air flowrate (F0) and 
NO flowrate (FNO) (see Figure 1) must be adjusted such that 
the following relationship holds:
[GRAPHIC] [TIFF OMITTED] TC08NO91.076

[GRAPHIC] [TIFF OMITTED] TC08NO91.077

[GRAPHIC] [TIFF OMITTED] TC08NO91.078

where:

PR = dynamic parameter specification, determined empirically, 
to insure complete reaction of the available O3, ppm-minute
[NO]RC = NO concentration in the reaction chamber, ppm
R = residence time of the reactant gases in the reaction 
chamber, minute
[NO]STD = concentration of the undiluted NO standard, ppm
FNO = NO flowrate, scm 3/min
FO = O3 generator air flowrate, scm 3/
min
VRC = volume of the reaction chamber, scm 3

    1.4.2 The flow conditions to be used in the GPT system are 
determined by the following procedure:
    (a) Determine FT, the total flow required at the output 
manifold (FT=analyzer demand plus 10 to 50% excess).
    (b) Establish [NO]OUT as the highest NO concentration 
(ppm) which will be required at the output manifold. [NO]OUT 
should be approximately equivalent to 90% of the upper range limit (URL) 
of the NO2 concentration range to be covered.
    (c) Determine FNO as
    [GRAPHIC] [TIFF OMITTED] TC08NO91.079
    
    (d) Select a convenient or available reaction chamber volume. 
Initially, a trial VRC may be selected to be in the range of 
approximately 200 to 500 scm3.
    (e) Compute FO as
    
    
    (f) Compute tR as
    [GRAPHIC] [TIFF OMITTED] TC08NO91.080
    
Verify that tR  2 minutes. If not, select a reaction chamber 
with a smaller VRC.
    (g) Compute the diluent air flowrate as
    [GRAPHIC] [TIFF OMITTED] TC08NO91.081
    
where:

FD = diluent air flowrate, scm 3/min


[[Page 49]]


    (h) If FO turns out to be impractical for the desired 
system, select a reaction chamber having a different VRC and 
recompute FO and FD.
    Note: A dynamic parameter lower than 2.75 ppm-minutes may be used if 
it can be determined empirically that quantitative reaction of O3 
with NO occurs. A procedure for making this determination as well as a 
more detailed discussion of the above requirements and other related 
considerations is given in reference 13.
    1.5 Procedure.
    1.5.1 Assemble a dynamic calibration system such as the one shown in 
Figure 1.
    1.5.2 Insure that all flowmeters are calibrated under the conditions 
of use against a reliable standard such as a soap-bubble meter or wet-
test meter. All volumetric flowrates should be corrected to 25  deg.C 
and 760 mm Hg. A discussion on the calibration of flowmeters is given in 
reference 13.
    1.5.3 Precautions must be taken to remove O2 and other 
contaminants from the NO pressure regulator and delivery system prior to 
the start of calibration to avoid any conversion of the standard NO to 
NO2. Failure to do so can cause significant errors in 
calibration. This problem may be minimized by (1) carefully evacuating 
the regulator, when possible, after the regulator has been connected to 
the cylinder and before opening the cylinder valve; (2) thoroughly 
flushing the regulator and delivery system with NO after opening the 
cylinder valve; (3) not removing the regulator from the cylinder between 
calibrations unless absolutely necessary. Further discussion of these 
procedures is given in reference 13.
    1.5.4 Select the operating range of the NO/NOX/NO2 
analyzer to be calibrated. In order to obtain maximum precision and 
accuracy for NO2 calibration, all three channels of the 
analyzer should be set to the same range. If operation of the NO and 
NOX channels on higher ranges is desired, subsequent 
recalibration of the NO and NOX channels on the higher ranges 
is recommended.
    Note: Some analyzer designs may require identical ranges for NO, 
NOX, and NO2 during operation of the analyzer.
    1.5.5 Connect the recorder output cable(s) of the NO/NOX/
NO2 analyzer to the input terminals of the strip chart 
recorder(s). All adjustments to the analyzer should be performed based 
on the appropriate strip chart readings. References to analyzer 
responses in the procedures given below refer to recorder responses.
    1.5.6 Determine the GPT flow conditions required to meet the dynamic 
parameter specification as indicated in 1.4.
    1.5.7 Adjust the diluent air and O3 generator air flows 
to obtain the flows determined in section 1.4.2. The total air flow must 
exceed the total demand of the analyzer(s) connected to the output 
manifold to insure that no ambient air is pulled into the manifold vent. 
Allow the analyzer to sample zero air until stable NO, NOX, 
and NO2 responses are obtained. After the responses have 
stabilized, adjust the analyzer zero control(s).
    Note: Some analyzers may have separate zero controls for NO, 
NOX, and NO2. Other analyzers may have separate 
zero controls only for NO and NOX, while still others may 
have only one zero control common to all three channels.
    Offsetting the analyzer zero adjustments to +5 percent of scale is 
recommended to facilitate observing negative zero drift. Record the 
stable zero air responses as ZNO, Znox, and Zno2.
    1.5.8 Preparation of NO and NOX calibration curves.
    1.5.8.1 Adjustment of NO span control. Adjust the NO flow from the 
standard NO cylinder to generate an NO concentration of approximately 80 
percent of the upper range limit (URL) of the NO range. This exact NO 
concentration is calculated from:
[GRAPHIC] [TIFF OMITTED] TR31AU93.044

where:

[NO]OUT = diluted NO concentration at the output manifold, 
ppm

Sample this NO concentration until the NO and NOX responses 
have stabilized. Adjust the NO span control to obtain a recorder 
response as indicated below:

recorder response (percent scale) =
[GRAPHIC] [TIFF OMITTED] TR31AU93.045

where:

URL = nominal upper range limit of the NO channel, ppm
    Note: Some analyzers may have separate span controls for NO, 
NOX, and NO2. Other analyzers may have separate 
span controls only for NO and NOX, while still others may 
have only one span control common to all three channels. When only one 
span control is available, the span adjustment is made on the NO channel 
of the analyzer.
If substantial adjustment of the NO span control is necessary, it may be 
necessary to recheck the zero and span adjustments by repeating steps 
1.5.7 and 1.5.8.1. Record the NO concentration and the analyzer's NO 
response.
    1.5.8.2 Adjustment of NOX span control. When adjusting 
the analyzer's NOX span control, the presence of any NO2 
impurity in the standard NO cylinder must be taken into account. 
Procedures for determining the amount of NO2 impurity in the 
standard NO

[[Page 50]]

cylinder are given in reference 13. The exact NOX 
concentration is calculated from:
[GRAPHIC] [TIFF OMITTED] TR31AU93.046

where:

[NOX]OUT = diluted NOX concentration at 
the output manifold, ppm
[NO2]IMP = concentration of NO2 
impurity in the standard NO cylinder, ppm

Adjust the NOX span control to obtain a recorder response as 
indicated below:

recorder response (% scale) =
[GRAPHIC] [TIFF OMITTED] TR31AU93.047

    Note: If the analyzer has only one span control, the span adjustment 
is made on the NO channel and no further adjustment is made here for 
NOx.
If substantial adjustment of the NOX span control is 
necessary, it may be necessary to recheck the zero and span adjustments 
by repeating steps 1.5.7 and 1.5.8.2. Record the NOX 
concentration and the analyzer's NOX response.
    1.5.8.3 Generate several additional concentrations (at least five 
evenly spaced points across the remaining scale are suggested to verify 
linearity) by decreasing FNO or increasing FD. For 
each concentration generated, calculate the exact NO and NOX 
concentrations using equations (9) and (11) respectively. Record the 
analyzer's NO and NOX responses for each concentration. Plot 
the analyzer responses versus the respective calculated NO and NOX 
concentrations and draw or calculate the NO and NOX 
calibration curves. For subsequent calibrations where linearity can be 
assumed, these curves may be checked with a two-point calibration 
consisting of a zero air point and NO and NOX concentrations 
of approximately 80% of the URL.
    1.5.9 Preparation of NO2 calibration curve.
    1.5.9.1 Assuming the NO2 zero has been properly adjusted 
while sampling zero air in step 1.5.7, adjust FO and FD 
as determined in section 1.4.2. Adjust FNO to generate an NO 
concentration near 90% of the URL of the NO range. Sample this NO 
concentration until the NO and NOX responses have stabilized. 
Using the NO calibration curve obtained in section 1.5.8, measure and 
record the NO concentration as [NO]orig. Using the NOX 
calibration curve obtained in section 1.5.8, measure and record the 
NOX concentration as [NOX]orig.
    1.5.9.2 Adjust the O3 generator to generate sufficient 
O3 to produce a decrease in the NO concentration equivalent 
to approximately 80% of the URL of the NO2 range. The 
decrease must not exceed 90% of the NO concentration determined in step 
1.5.9.1. After the analyzer responses have stabilized, record the 
resultant NO and NOX concentrations as [NO]rem and 
[NOX]rem.
    1.5.9.3 Calculate the resulting NO2 concentration from:
    [GRAPHIC] [TIFF OMITTED] TC08NO91.082
    
where:

[NO2]OUT = diluted NO2 concentration at 
the output manifold, ppm
[NO]orig = original NO concentration, prior to addition of 
O3, ppm
[NO]rem = NO concentration remaining after addition of 
O3, ppm

Adjust the NO2 span control to obtain a recorder response as 
indicated below:

recorder response (% scale) =
[GRAPHIC] [TIFF OMITTED] TR31AU93.048

    Note: If the analyzer has only one or two span controls, the span 
adjustments are made on the NO channel or NO and NOX channels 
and no further adjustment is made here for NO2.
If substantial adjustment of the NO2 span control is 
necessary, it may be necessary to recheck the zero and span adjustments 
by repeating steps 1.5.7 and 1.5.9.3. Record the NO2 
concentration and the corresponding analyzer NO2 and NOX 
responses.
    1.5.9.4 Maintaining the same FNO, FO, and 
FD as in section 1.5.9.1, adjust the ozone generator to 
obtain several other concentrations of NO2 over the NO2 
range (at least five evenly spaced points across the remaining scale are 
suggested). Calculate each NO2 concentration using equation 
(13) and record the corresponding analyzer NO2 and NOX 
responses. Plot the analyzer's NO2 responses versus the 
corresponding calculated NO2 concentrations and draw or 
calculate the NO2 calibration curve.
    1.5.10 Determination of converter efficiency.

[[Page 51]]

    1.5.10.1 For each NO2 concentration generated during the 
preparation of the NO2 calibration curve (see section 1.5.9) 
calculate the concentration of NO2 converted from:
[GRAPHIC] [TIFF OMITTED] TC08NO91.083

where:

[NO2]CONV = concentration of NO2 
converted, ppm
[NOX]orig = original NOX concentration 
prior to addition of O3, ppm
[NOX]rem = NOX concentration remaining 
after addition of O3, ppm

    Note: Supplemental information on calibration and other procedures 
in this method are given in reference 13.
Plot [NO2]CONV (y-axis) versus 
[NO2]OUT (x-axis) and draw or calculate the 
converter efficiency curve. The slope of the curve times 100 is the 
average converter efficiency, EC. The average converter 
efficiency must be greater than 96%; if it is less than 96%, replace or 
service the converter.
    2. Alternative B--NO2 permeation device.
    Major equipment required:
    Stable O3 generator.
    Chemiluminescence NO/NOX/NO2 analyzer with 
strip chart recorder(s).
    NO concentration standard.
    NO2 concentration standard.
    2.1 Principle. Atmospheres containing accurately known 
concentrations of nitrogen dioxide are generated by means of a 
permeation device. (10) The permeation device emits NO2 at a 
known constant rate provided the temperature of the device is held 
constant (plus-minus0.1  deg.C) and the device has been 
accurately calibrated at the temperature of use. The NO2 
emitted from the device is diluted with zero air to produce NO2 
concentrations suitable for calibration of the NO2 channel of 
the NO/NOX/NO2 analyzer. An NO concentration 
standard is used for calibration of the NO and NOX channels 
of the analyzer.
    2.2 Apparatus. A typical system suitable for generating the required 
NO and NO2 concentrations is shown in Figure 2. All 
connections between components downstream from the permeation device 
should be of glass, Teflon, or other non-reactive material.
    2.2.1 Air flow controllers. Devices capable of maintaining constant 
air flows within plus-minus2% of the required flowrate.
    2.2.2 NO flow controller. A device capable of maintaining constant 
NO flows within plus-minus2% of the required flowrate. 
Component parts in contact with the NO must be of a non-reactive 
material.
    2.2.3 Air flowmeters. Calibrated flowmeters capable of measuring and 
monitoring air flowrates with an accuracy of plus-minus2% of 
the measured flowrate.
    2.2.4 NO flowmeter. A calibrated flowmeter capable of measuring and 
monitoring NO flowrates with an accuracy of plus-minus2% of 
the measured flowrate. (Rotameters have been reported to operate 
unreliably when measuring low NO flows and are not recommended.)
    2.2.5 Pressure regulator for standard NO cylinder. This regulator 
must have a non-reactive diaphragm and internal parts and a suitable 
delivery pressure.
    2.2.6 Drier. Scrubber to remove moisture from the permeation device 
air system. The use of the drier is optional with NO2 
permeation devices not sensitive to moisture. (Refer to the supplier's 
instructions for use of the permeation device.)
    2.2.7 Constant temperature chamber. Chamber capable of housing the 
NO2 permeation device and maintaining its temperature to 
within plus-minus0.1  deg.C.
    2.2.8 Temperature measuring device. Device capable of measuring and 
monitoring the temperature of the NO2 permeation device with 
an accuracy of plus-minus0.05  deg.C.
    2.2.9 Valves. A valve may be used as shown in Figure 2 to divert the 
NO2 from the permeation device when zero air or NO is 
required at the manifold. A second valve may be used to divert the NO 
flow when zero air or NO2 is required at the manifold.
    The valves should be constructed of glass, Teflon, or 
other nonreactive material.
    2.2.10 Mixing chamber. A chamber constructed of glass, 
Teflon, or other nonreactive material and designed to 
provide thorough mixing of pollutant gas streams and diluent air.
    2.2.11 Output manifold. The output manifold should be constructed of 
glass, Teflon, or other non-reactive material and should be 
of sufficient diameter to insure an insignificant pressure drop at the 
analyzer connection. The system must have a vent designed to insure 
atmospheric pressure at the manifold and to prevent ambient air from 
entering the manifold.
    2.3 Reagents.
    2.3.1 Calibration standards. Calibration standards are required for 
both NO and NO2. The reference standard for the calibration 
may be either an NO or NO2 standard, and must be traceable to 
a National Bureau of Standards (NBS) NO in N2 Standard 
Reference Material (SRM 1683 or SRM 1684), and NBS NO2 
Standard Reference Material (SRM 1629), or an NBS/EPA-approved 
commercially

[[Page 52]]

available Certified Reference Material (CRM). CRM's are described in 
Reference 14, and a list of CRM sources is available from the address 
shown for Reference 14. Reference 15 gives recommended procedures for 
certifying an NO gas cylinder against an NO SRM or CRM and for 
certifying an NO2 permeation device against an NO2 
SRM. Reference 13 contains procedures for certifying an NO gas cylinder 
against an NO2 SRM and for certifying an NO2 
permeation device against an NO SRM or CRM. A procedure for determining 
the amount of NO2 impurity in an NO cylinder is also 
contained in Reference 13. The NO or NO2 standard selected as 
the reference standard must be used to certify the other standard to 
ensure consistency between the two standards.
    2.3.1.1 NO2 Concentration standard. A permeation device 
suitable for generating NO2 concentrations at the required 
flow-rates over the required concentration range. If the permeation 
device is used as the reference standard, it must be traceable to an SRM 
or CRM as specified in 2.3.1. If an NO cylinder is used as the reference 
standard, the NO2 permeation device must be certified against 
the NO standard according to the procedure given in Reference 13. The 
use of the permeation device should be in strict accordance with the 
instructions supplied with the device. Additional information regarding 
the use of permeation devices is given by Scaringelli et al. (11) and 
Rook et al. (12).
    2.3.1.2 NO Concentration standard. Gas cylinder containing 50 to 100 
ppm NO in N2 with less than 1 ppm NO2. If this 
cylinder is used as the reference standard, the cylinder must be 
traceable to an SRM or CRM as specified in 2.3.1. If an NO2 
permeation device is used as the reference standard, the NO cylinder 
must be certified against the NO2 standard according to the 
procedure given in Reference 13. The cylinder should be recertified on a 
regular basis as determined by the local quality control program.
    2.3.3 Zero air. Air, free of contaminants which might react with NO 
or NO2 or cause a detectable response on the NO/
NOX/NO2 analyzer. When using permeation devices 
that are sensitive to moisture, the zero air passing across the 
permeation device must be dry to avoid surface reactions on the device. 
(Refer to the supplier's instructions for use of the permeation device.) 
A procedure for generating zero air is given in reference 13.
    2.4 Procedure.
    2.4.1 Assemble the calibration apparatus such as the typical one 
shown in Figure 2.
    2.4.2 Insure that all flowmeters are calibrated under the conditions 
of use against a reliable standard such as a soap bubble meter or wet-
test meter. All volumetric flowrates should be corrected to 25  deg.C 
and 760 mm Hg. A discussion on the calibration of flowmeters is given in 
reference 13.
    2.4.3 Install the permeation device in the constant temperature 
chamber. Provide a small fixed air flow (200-400 scm 3/min) 
across the device. The permeation device should always have a continuous 
air flow across it to prevent large buildup of NO2 in the 
system and a consequent restabilization period. Record the flowrate as 
FP. Allow the device to stabilize at the calibration temperature for at 
least 24 hours. The temperature must be adjusted and controlled to 
within plus-minus0.1  deg.C or less of the calibration 
temperature as monitored with the temperature measuring device.
    2.4.4 Precautions must be taken to remove O2 and other 
contaminants from the NO pressure regulator and delivery system prior to 
the start of calibration to avoid any conversion of the standard NO to 
NO2. Failure to do so can cause significant errors in 
calibration. This problem may be minimized by
    (1) Carefully evacuating the regulator, when possible, after the 
regulator has been connected to the cylinder and before opening the 
cylinder valve;
    (2) Thoroughly flushing the regulator and delivery system with NO 
after opening the cylinder valve;
    (3) Not removing the regulator from the cylinder between 
calibrations unless absolutely necessary. Further discussion of these 
procedures is given in reference 13.
    2.4.5 Select the operating range of the NO/NOX NO2 
analyzer to be calibrated. In order to obtain maximum precision and 
accuracy for NO2 calibration, all three channels of the 
analyzer should be set to the same range. If operation of the NO and 
NOX channels on higher ranges is desired, subsequent 
recalibration of the NO and NOX channels on the higher ranges 
is recommended.
    Note: Some analyzer designs may require identical ranges for NO, 
NOX, and NO2 during operation of the analyzer.
    2.4.6 Connect the recorder output cable(s) of the NO/NOX/
NO2 analyzer to the input terminals of the strip chart 
recorder(s). All adjustments to the analyzer should be performed based 
on the appropriate strip chart readings. References to analyzer 
responses in the procedures given below refer to recorder responses.
    2.4.7 Switch the valve to vent the flow from the permeation device 
and adjust the diluent air flowrate, FD, to provide zero air 
at the output manifold. The total air flow must exceed the total demand 
of the analyzer(s) connected to the output manifold to insure that no 
ambient air is pulled into the manifold vent. Allow the analyzer to 
sample zero air until stable NO, NOX, and NO2 
responses are obtained. After the responses have stabilized, adjust the 
analyzer zero control(s).
    Note: Some analyzers may have separate zero controls for NO, 
NOX, and NO2. Other analyzers may have separate 
zero controls only for NO and NOX, while still others may

[[Page 53]]

have only one zero common control to all three channels.
Offsetting the analyzer zero adjustments to +5% of scale is recommended 
to facilitate observing negative zero drift. Record the stable zero air 
responses as ZNO, ZNOX, and ZNO2.
    2.4.8 Preparation of NO and NOX calibration curves.
    2.4.8.1 Adjustment of NO span control. Adjust the NO flow from the 
standard NO cylinder to generate an NO concentration of approximately 
80% of the upper range limit (URL) of the NO range. The exact NO 
concentration is calculated from:
[GRAPHIC] [TIFF OMITTED] TR31AU93.049

where:

[NO]OUT = diluted NO concentration at the output manifold, 
ppm
FNO = NO flowrate, scm3/min
[NO]STD=concentration of the undiluted NO standard, ppm
FD = diluent air flowrate, scm 3/min

Sample this NO concentration until the NO and NOX responses 
have stabilized. Adjust the NO span control to obtain a recorder 
response as indicated below:

recorder response (% scale) =
[GRAPHIC] [TIFF OMITTED] TR31AU93.050

      
    [GRAPHIC] [TIFF OMITTED] TR31AU93.051
    
where:

URL = nominal upper range limit of the NO channel, ppm
    Note: Some analyzers may have separate span controls for NO, 
NOX, and NO2. Other analyzers may have separate 
span controls only for NO and NOX, while still others may 
have only one span control common to all three channels. When only one 
span control is available, the span adjustment is made on the NO channel 
of the analyzer.
If substantial adjustment of the NO span control is necessary, it may be 
necessary to recheck the zero and span adjustments by repeating steps 
2.4.7 and 2.4.8.1. Record the NO concentration and the analyzer's NO 
response.
    2.4.8.2 Adjustment of NOX span control. When adjusting 
the analyzer's NOX span control, the presence of any NO2 
impurity in the standard NO cylinder must be taken into account. 
Procedures for determining the amount of NO2 impurity in the 
standard NO cylinder are given in reference 13. The exact NOX 
concentration is calculated from:
[GRAPHIC] [TIFF OMITTED] TR31AU93.052


where:
[NOX]OUT = diluted NOX cencentration at 
the output manifold, ppm
[NO2]IMP = concentration of NO2 
impurity in the standard NO cylinder, ppm

Adjust the NOX span control to obtain a convenient recorder 
response as indicated below:

recorder response (% scale)
[GRAPHIC] [TIFF OMITTED] TR31AU93.053

    Note: If the analyzer has only one span control, the span adjustment 
is made on the NO channel and no further adjustment is made here for 
NOX.
If substantial adjustment of the NOX span control is 
necessary, it may be necessary to recheck the zero and span adjustments 
by repeating steps 2.4.7 and 2.4.8.2. Record the NOX 
concentration and the analyzer's NOX response.
    2.4.8.3 Generate several additional concentrations (at least five 
evenly spaced points across the remaining scale are suggested to verify 
linearity) by decreasing FNO or increasing FD. For 
each concentration generated, calculate the exact NO and NOX 
concentrations using equations (16) and (18) respectively. Record the 
analyzer's NO and NOX responses for each concentration. Plot 
the analyzer responses versus the respective calculated NO and NOX 
concentrations and draw or calculate the NO and NOX 
calibration curves. For subsequent calibrations where linearity can be 
assumed, these curves may be checked with a two-point calibration 
consisting of a zero point and NO and NOX concentrations of 
approximately 80 percent of the URL.
    2.4.9 Preparation of NO2 calibration curve.
    2.4.9.1 Remove the NO flow. Assuming the NO2 zero has 
been properly adjusted while sampling zero air in step 2.4.7, switch the 
valve to provide NO2 at the output manifold.
    2.4.9.2 Adjust FD to generate an NO2 
concentration of approximately 80 percent of the URL of the NO2 
range. The total air flow must exceed the demand of the analyzer(s) 
under calibration. The actual concentration of NO2 is 
calculated from:
[GRAPHIC] [TIFF OMITTED] TR31AU93.054

where:


[[Page 54]]


[NO2]OUT = diluted NO2 concentration at 
the output manifold, ppm
R = permeation rate, g/min
K = 0.532l NO2/g NO2 (at 25 
deg.C and 760 mm Hg)
Fp = air flowrate across permeation device, scm 3/
min
FD = diluent air flowrate, scm 3/min

Sample this NO2 concentration until the NOX and 
NO2 responses have stabilized. Adjust the NO2 span 
control to obtain a recorder response as indicated below:

recorder response (% scale)
[GRAPHIC] [TIFF OMITTED] TR31AU93.055

    Note: If the analyzer has only one or two span controls, the span 
adjustments are made on the NO channel or NO and NOX channels 
and no further adjustment is made here for NO2.

If substantial adjustment of the NO2 span control is 
necessary it may be necessary to recheck the zero and span adjustments 
by repeating steps 2.4.7 and 2.4.9.2. Record the NO2 
concentration and the analyzer's NO2 response. Using the 
NOX calibration curve obtained in step 2.4.8, measure and 
record the NOX concentration as [NOX]M.
    2.4.9.3 Adjust FD to obtain several other concentrations 
of NO2 over the NO2 range (at least five evenly 
spaced points across the remaining scale are suggested). Calculate each 
NO2 concentration using equation (20) and record the 
corresponding analyzer NO2 and NOX responses. Plot 
the analyzer's NO2 responses versus the corresponding 
calculated NO2 concentrations and draw or calculate the 
NO2 calibration curve.
    2.4.10 Determination of converter efficiency.
    2.4.10.1 Plot [NOX]M (y-axis) versus 
[NO2]OUT (x-axis) and draw or calculate the 
converter efficiency curve. The slope of the curve times 100 is the 
average converter efficiency, EC. The average converter 
efficiency must be greater than 96 percent; if it is less than 96 
percent, replace or service the converter.
    Note: Supplemental information on calibration and other procedures 
in this method are given in reference 13.
    3. Frequency of calibration. The frequency of calibration, as well 
as the number of points necessary to establish the calibration curve and 
the frequency of other performance checks, will vary from one analyzer 
to another. The user's quality control program should provide guidelines 
for initial establishment of these variables and for subsequent 
alteration as operational experience is accumulated. Manufacturers of 
analyzers should include in their instruction/operation manuals 
information and guidance as to these variables and on other matters of 
operation, calibration, and quality control.

                               References

    1. A. Fontijn, A. J. Sabadell, and R. J. Ronco, ``Homogeneous 
Chemiluminescent Measurement of Nitric Oxide with Ozone,'' Anal. Chem., 
42, 575 (1970).
    2. D. H. Stedman, E. E. Daby, F. Stuhl, and H. Niki, ``Analysis of 
Ozone and Nitric Oxide by a Chemiluminiscent Method in Laboratory and 
Atmospheric Studies of Photochemical Smog,'' J. Air Poll. Control 
Assoc., 22, 260 (1972).
    3. B. E. Martin, J. A. Hodgeson, and R. K. Stevens, ``Detection of 
Nitric Oxide Chemiluminescence at Atmospheric Pressure,'' Presented at 
164th National ACS Meeting, New York City, August 1972.
    4. J. A. Hodgeson, K. A. Rehme, B. E. Martin, and R. K. Stevens, 
``Measurements for Atmospheric Oxides of Nitrogen and Ammonia by 
Chemiluminescence,'' Presented at 1972 APCA Meeting, Miami, FL, June 
1972.
    5. R. K. Stevens and J. A. Hodgeson, ``Applications of 
Chemiluminescence Reactions to the Measurement of Air Pollutants,'' 
Anal. Chem., 45, 443A (1973).
    6. L. P. Breitenbach and M. Shelef, ``Development of a Method for 
the Analysis of NO2 and NH3 by NO-Measuring 
Instruments,'' J. Air Poll. Control Assoc., 23, 128 (1973).
    7. A. M. Winer, J. W. Peters, J. P. Smith, and J. N. Pitts, Jr., 
``Response of Commercial Chemiluminescent NO-NO2 Analyzers to 
Other Nitrogen-Containing Compounds,'' Environ. Sci. Technol., 8, 1118 
(1974).
    8. K. A. Rehme, B. E. Martin, and J. A. Hodgeson, Tentative Method 
for the Calibration of Nitric Oxide, Nitrogen Dioxide, and Ozone 
Analyzers by Gas Phase Titration,'' EPA-R2-73-246, March 1974.
    9. J. A. Hodgeson, R. K. Stevens, and B. E. Martin, ``A Stable Ozone 
Source Applicable as a Secondary Standard for Calibration of Atmospheric 
Monitors,'' ISA Transactions, 11, 161 (1972).
    10. A. E. O'Keeffe and G. C. Ortman, ``Primary Standards for Trace 
Gas Analysis,'' Anal. Chem., 38, 760 (1966).
    11. F. P. Scaringelli, A. E. O'Keeffe, E. Rosenberg, and J. P. Bell, 
``Preparation of Known Concentrations of Gases and Vapors with 
Permeation Devices Calibrated Gravimetrically,'' Anal. Chem., 42, 871 
(1970).
    12. H. L. Rook, E. E. Hughes, R. S. Fuerst, and J. H. Margeson, 
``Operation Characteristics of NO2 Permeation Devices,'' 
Presented at 167th National ACS Meeting, Los Angeles, CA, April 1974.
    13. E. C. Ellis, ``Technical Assistance Document for the 
Chemiluminescence Measurement of Nitrogen Dioxide,'' EPA-E600/4-75-003 
(Available in draft form from the United States Environmental Protection 
Agency,

[[Page 55]]

Department E (MD-76), Environmental Monitoring and Support Laboratory, 
Research Triangle Park, NC 27711).
    14. A Procedure for Establishing Traceability of Gas Mixtures to 
Certain National Bureau of Standards Standard Reference Materials. EPA-
600/7-81-010, Joint publication by NBS and EPA. Available from the U.S. 
Environmental Protection Agency, Environmental Monitoring Systems 
Laboratory (MD-77), Research Triangle Park, NC 27711, May 1981.
    15. Quality Assurance Handbook for Air Pollution Measurement 
Systems, Volume II, Ambient Air Specific Methods. The U.S. Environmental 
Protection Agency, Environmental Monitoring Systems Laboratory, Research 
Triangle Park, NC 27711. Publication No. EAP-600/4-77-027a.



[[Page 56]]




[41 FR 52688, Dec. 1, 1976, as amended at 48 FR 2529, Jan 20, 1983]

Appendix G to Part 50--Reference Method for the Determination of Lead in 
         Suspended Particulate Matter Collected From Ambient Air

    1. Principle and applicability.
    1.1 Ambient air suspended particulate matter is collected on a 
glass-fiber filter for 24 hours using a high volume air sampler. The 
analysis of the 24-hour samples may be performed for either individual 
samples or composites of the samples collected over a calendar month or 
quarter, provided that the compositing procedure has been approved in 
accordance with section 2.8 of appendix C to part 58 of this chapter--
Modifications of methods by users. (Guidance or assistance in requesting 
approval under Section 2.8 can be obtained from the address given in 
section 2.7 of appendix C to part 58 of this chapter.)
    1.2 Lead in the particulate matter is solubilized by extraction with 
nitric acid (HNO3), facilitated by heat or by a mixture of 
HNO3 and hydrochloric acid (HCl) facilitated by 
ultrasonication.
    1.3 The lead content of the sample is analyzed by atomic absorption 
spectrometry using an air-acetylene flame, the 283.3 or 217.0 nm lead 
absorption line, and the optimum instrumental conditions recommended by 
the manufacturer.
    1.4 The ultrasonication extraction with HNO3/HCl will 
extract metals other than lead from ambient particulate matter.
    2. Range, sensitivity, and lower detectable limit. The values given 
below are typical of the methods capabilities. Absolute values will vary 
for individual situations depending on the type of instrument used, the 
lead line, and operating conditions.
    2.1 Range. The typical range of the method is 0.07 to 7.5 g 
Pb/m3 assuming an upper linear range of analysis of 15 
g/ml and an air volume of 2,400 m3.
    2.2 Sensitivity. Typical sensitivities for a 1 percent change in 
absorption (0.0044 absorbance units) are 0.2 and 0.5 g Pb/ml 
for the 217.0 and 283.3 nm lines, respectively.
    2.3 Lower detectable limit (LDL). A typical LDL is 0.07 g 
Pb/m3. The above value was calculated by doubling the 
between-laboratory standard deviation obtained for the lowest measurable 
lead concentration in a collaborative test of the method.(15) An air 
volume of 2,400 m3 was assumed.
    3. Interferences. Two types of interferences are possible: chemical 
and light scattering.
    3.1 Chemical. Reports on the absence (1, 2, 3, 4, 5) of chemical 
interferences far outweigh those reporting their presence, (6) 
therefore, no correction for chemical interferences is given here. If 
the analyst suspects that the sample matrix is causing a chemical 
interference, the interference can be verified and corrected for by 
carrying out the analysis with and without the method of standard 
additions.(7)

[[Page 57]]

    3.2 Light scattering. Nonatomic absorption or light scattering, 
produced by high concentrations of dissolved solids in the sample, can 
produce a significant interference, especially at low lead 
concentrations. (2) The interference is greater at the 217.0 nm line 
than at the 283.3 nm line. No interference was observed using the 283.3 
nm line with a similar method.(1)
    Light scattering interferences can, however, be corrected for 
instrumentally. Since the dissolved solids can vary depending on the 
origin of the sample, the correction may be necessary, especially when 
using the 217.0 nm line. Dual beam instruments with a continuum source 
give the most accurate correction. A less accurate correction can be 
obtained by using a nonabsorbing lead line that is near the lead 
analytical line. Information on use of these correction techniques can 
be obtained from instrument manufacturers' manuals.
    If instrumental correction is not feasible, the interference can be 
eliminated by use of the ammonium pyrrolidinecarbodithioate-
methylisobutyl ketone, chelation-solvent extraction technique of sample 
preparation.(8)
    4. Precision and bias.
    4.1 The high-volume sampling procedure used to collect ambient air 
particulate matter has a between-laboratory relative standard deviation 
of 3.7 percent over the range 80 to 125 g/m3.(9) The 
combined extraction-analysis procedure has an average within-laboratory 
relative standard deviation of 5 to 6 percent over the range 1.5 to 15 
g Pb/ml, and an average between laboratory relative standard 
deviation of 7 to 9 percent over the same range. These values include 
use of either extraction procedure.
    4.2 Single laboratory experiments and collaborative testing indicate 
that there is no significant difference in lead recovery between the hot 
and ultrasonic extraction procedures.(15)
    5. Apparatus.
    5.1 Sampling.
    5.1.1 High-Volume Sampler. Use and calibrate the sampler as 
described in appendix B to this part.
    5.2 Analysis.
    5.2.1 Atomic absorption spectrophotometer. Equipped with lead hollow 
cathode or electrodeless discharge lamp.
    5.2.1.1 Acetylene. The grade recommended by the instrument 
manufacturer should be used. Change cylinder when pressure drops below 
50-100 psig.
    5.2.1.2 Air. Filtered to remove particulate, oil, and water.
    5.2.2 Glassware. Class A borosilicate glassware should be used 
throughout the analysis.
    5.2.2.1 Beakers. 30 and 150 ml. graduated, Pyrex.
    5.2.2.2 Volumetric flasks. 100-ml.
    5.2.2.3 Pipettes. To deliver 50, 30, 15, 8, 4, 2, 1 ml.
    5.2.2.4 Cleaning. All glassware should be scrupulously cleaned. The 
following procedure is suggested. Wash with laboratory detergent, rinse, 
soak for 4 hours in 20 percent (w/w) HNO3, rinse 3 times with 
distilled-deionized water, and dry in a dust free manner.
    5.2.3 Hot plate.
    5.2.4. Ultrasonication water bath, unheated. Commercially available 
laboratory ultrasonic cleaning baths of 450 watts or higher ``cleaning 
power,'' i.e., actual ultrasonic power output to the bath have been 
found satisfactory.
    5.2.5 Template. To aid in sectioning the glass-fiber filter. See 
figure 1 for dimensions.
    5.2.6 Pizza cutter. Thin wheel. Thickness 1mm.
    5.2.7 Watch glass.
    5.2.8 Polyethylene bottles. For storage of samples. Linear 
polyethylene gives better storage stability than other polyethylenes and 
is preferred.
    5.2.9 Parafilm ``M''.\1\ American Can Co., Marathon Products, 
Neenah, Wis., or equivalent.
---------------------------------------------------------------------------

    \1\ Mention of commercial products does not imply endorsement by the 
U.S. Environmental Protection Agency.
---------------------------------------------------------------------------

    6. Reagents.
    6.1 Sampling.
    6.1.1 Glass fiber filters. The specifications given below are 
intended to aid the user in obtaining high quality filters with 
reproducible properties. These specifications have been met by EPA 
contractors.
    6.1.1.1 Lead content. The absolute lead content of filters is not 
critical, but low values are, of course, desirable. EPA typically 
obtains filters with a lead content of 75 g/filter.
    It is important that the variation in lead content from filter to 
filter, within a given batch, be small.
    6.1.1.2 Testing.
    6.1.1.2.1 For large batches of filters (>500 filters) select at 
random 20 to 30 filters from a given batch. For small batches (>500 
filters) a lesser number of filters may be taken. Cut one \3/4\" x 8" 
strip from each filter anywhere in the filter. Analyze all strips, 
separately, according to the directions in sections 7 and 8.
    6.1.1.2.2 Calculate the total lead in each filter as
    [GRAPHIC] [TIFF OMITTED] TC08NO91.084
    
where:

Fb = Amount of lead per 72 square inches of filter, 
g.

    6.1.1.2.3 Calculate the mean, Fb, of the values and the 
relative standard deviation (standard deviation/mean  x  100). If the 
relative standard deviation is high enough so

[[Page 58]]

that, in the analysts opinion, subtraction of Fb, (section 
10.3) may result in a significant error in the g Pb/m3, 
the batch should be rejected.
    6.1.1.2.4 For acceptable batches, use the value of Fb to 
correct all lead analyses (section 10.3) of particulate matter collected 
using that batch of filters. If the analyses are below the LDL (section 
2.3) no correction is necessary.
    6.2 Analysis.
    6.2.1 Concentrated (15.6 M) HNO3. ACS reagent grade 
HNO3 and commercially available redistilled HNO3 
has found to have sufficiently low lead concentrations.
    6.2.2 Concentrated (11.7 M) HCl. ACS reagent grade.
    6.2.3 Distilled-deionized water. (D.I. water).
    6.2.4 3 M HNO3. This solution is used in the hot 
extraction procedure. To prepare, add 192 ml of concentrated HNO3 
to D.I. water in a 1 l volumetric flask. Shake well, cool, and dilute to 
volume with D.I. water. Caution: Nitric acid fumes are toxic. Prepare in 
a well ventilated fume hood.
    6.2.5 0.45 M HNO3. This solution is used as the matrix 
for calibration standards when using the hot extraction procedure. To 
prepare, add 29 ml of concentrated HNO3 to D.I. water in a 1 
l volumetric flask. Shake well, cool, and dilute to volume with D.I. 
water.
    6.2.6 2.6 M HNO3+0 to 0.9 M HCl. This solution is used in 
the ultrasonic extraction procedure. The concentration of HCl can be 
varied from 0 to 0.9 M. Directions are given for preparation of a 2.6 M 
HNO3+0.9 M HCl solution. Place 167 ml of concentrated 
HNO3 into a 1 l volumetric flask and add 77 ml of 
concentrated HCl. Stir 4 to 6 hours, dilute to nearly 1 l with D.I. 
water, cool to room temperature, and dilute to 1 l.
    6.2.7 0.40 M HNO3 + X M HCl. This solution is used as the 
matrix for calibration standards when using the ultrasonic extraction 
procedure. To prepare, add 26 ml of concentrated HNO3, plus 
the ml of HCl required, to a 1 l volumetric flask. Dilute to nearly 1 l 
with D.I. water, cool to room temperature, and dilute to 1 l. The amount 
of HCl required can be determined from the following equation:
[GRAPHIC] [TIFF OMITTED] TC08NO91.085

where:

y = ml of concentrated HCl required.
x = molarity of HCl in 6.2.6.
0.15 = dilution factor in 7.2.2.

    6.2.8 Lead nitrate, Pb(NO3)2. ACS reagent 
grade, purity 99.0 percent. Heat for 4 hours at 120  deg.C and cool in a 
desiccator.
    6.3 Calibration standards.
    6.3.1 Master standard, 1000 g Pb/ml in HNO3. 
Dissolve 1.598 g of Pb(NO3)2 in 0.45 M HNO3 
contained in a 1 l volumetric flask and dilute to volume with 0.45 M 
HNO3.
    6.3.2 Master standard, 1000 g Pb/ml in HNO3/HCl. 
Prepare as in section 6.3.1 except use the HNO3/HCl solution 
in section 6.2.7.
    Store standards in a polyethylene bottle. Commercially available 
certified lead standard solutions may also be used.
    7. Procedure.
    7.1 Sampling. Collect samples for 24 hours using the procedure 
described in reference 10 with glass-fiber filters meeting the 
specifications in section 6.1.1. Transport collected samples to the 
laboratory taking care to minimize contamination and loss of sample. 
(16).
    7.2 Sample preparation.
    7.2.1 Hot extraction procedure.
    7.2.1.1 Cut a \3/4\" x 8" strip from the exposed filter using a 
template and a pizza cutter as described in Figures 1 and 2. Other 
cutting procedures may be used.
    Lead in ambient particulate matter collected on glass fiber filters 
has been shown to be uniformly distributed across the filter.1, 
3, 11 Another study 12 has shown that when 
sampling near a roadway, strip position contributes significantly to the 
overall variability associated with lead analyses. Therefore, when 
sampling near a roadway, additional strips should be analyzed to 
minimize this variability.
    7.2.1.2 Fold the strip in half twice and place in a 150-ml beaker. 
Add 15 ml of 3 M HNO3 to cover the sample. The acid should 
completely cover the sample. Cover the beaker with a watch glass.
    7.2.1.3 Place beaker on the hot-plate, contained in a fume hood, and 
boil gently for 30 min. Do not let the sample evaporate to dryness. 
Caution: Nitric acid fumes are toxic.
    7.2.1.4 Remove beaker from hot plate and cool to near room 
temperature.
    7.2.1.5 Quantitatively transfer the sample as follows:
    7.2.1.5.1 Rinse watch glass and sides of beaker with D.I. water.
    7.2.1.5.2 Decant extract and rinsings into a 100-ml volumetric 
flask.
    7.2.1.5.3 Add D.I. water to 40 ml mark on beaker, cover with watch 
glass, and set aside for a minimum of 30 minutes. This is a critical 
step and cannot be omitted since it allows the HNO3 trapped 
in the filter to diffuse into the rinse water.
    7.2.1.5.4 Decant the water from the filter into the volumetric 
flask.
    7.2.1.5.5 Rinse filter and beaker twice with D.I. water and add 
rinsings to volumetric flask until total volume is 80 to 85 ml.
    7.2.1.5.6 Stopper flask and shake vigorously. Set aside for 
approximately 5 minutes or until foam has dissipated.
    7.2.1.5.7 Bring solution to volume with D.I. water. Mix thoroughly.
    7.2.1.5.8 Allow solution to settle for one hour before proceeding 
with analysis.

[[Page 59]]

    7.2.1.5.9 If sample is to be stored for subsequent analysis, 
transfer to a linear polyethylene bottle.
    7.2.2 Ultrasonic extraction procedure.
    7.2.2.1 Cut a \3/4\" x 8" strip from the exposed filter as described 
in section 7.2.1.1.
    7.2.2.2 Fold the strip in half twice and place in a 30 ml beaker. 
Add 15 ml of the HNO3/HCl solution in section 6.2.6. The acid 
should completely cover the sample. Cover the beaker with parafilm.
    The parafilm should be placed over the beaker such that none of the 
parafilm is in contact with water in the ultrasonic bath. Otherwise, 
rinsing of the parafilm (section 7.2.2.4.1) may contaminate the sample.
    7.2.2.3 Place the beaker in the ultrasonication bath and operate for 
30 minutes.
    7.2.2.4 Quantitatively transfer the sample as follows:
    7.2.2.4.1 Rinse parafilm and sides of beaker with D.I. water.
    7.2.2.4.2 Decant extract and rinsings into a 100 ml volumetric 
flask.
    7.2.2.4.3 Add 20 ml D.I. water to cover the filter strip, cover with 
parafilm, and set aside for a minimum of 30 minutes. This is a critical 
step and cannot be omitted. The sample is then processed as in sections 
7.2.1.5.4 through 7.2.1.5.9.
    Note: Samples prepared by the hot extraction procedure are now in 
0.45 M HNO3. Samples prepared by the ultrasonication 
procedure are in 0.40 M HNO3 + X M HCl.
    8. Analysis.
    8.1 Set the wavelength of the monochromator at 283.3 or 217.0 nm. 
Set or align other instrumental operating conditions as recommended by 
the manufacturer.
    8.2 The sample can be analyzed directly from the volumetric flask, 
or an appropriate amount of sample decanted into a sample analysis tube. 
In either case, care should be taken not to disturb the settled solids.
    8.3 Aspirate samples, calibration standards and blanks (section 9.2) 
into the flame and record the equilibrium absorbance.
    8.4 Determine the lead concentration in g Pb/ml, from the 
calibration curve, section 9.3.
    8.5 Samples that exceed the linear calibration range should be 
diluted with acid of the same concentration as the calibration standards 
and reanalyzed.
    9. Calibration.
    9.1 Working standard, 20 g Pb/ml. Prepared by diluting 2.0 
ml of the master standard (section 6.3.1 if the hot acid extraction was 
used or section 6.3.2 if the ultrasonic extraction procedure was used) 
to 100 ml with acid of the same concentration as used in preparing the 
master standard.
    9.2 Calibration standards. Prepare daily by diluting the working 
standard, with the same acid matrix, as indicated below. Other lead 
concentrations may be used.

------------------------------------------------------------------------
                                                           Concentration
 Volume of 20 g/ml working standard,     Final    g Pb/
                      ml                       volume, ml        ml
------------------------------------------------------------------------
0............................................         100             0
1.0..........................................         200           0.1
2.0..........................................         200           0.2
2.0..........................................         100           0.4
4.0..........................................         100           0.8
8.0..........................................         100           1.6
15.0.........................................         100           3.0
30.0.........................................         100           6.0
50.0.........................................         100          10.0
100.0........................................         100          20.0
------------------------------------------------------------------------

    9.3 Preparation of calibration curve. Since the working range of 
analysis will vary depending on which lead line is used and the type of 
instrument, no one set of instructions for preparation of a calibration 
curve can be given. Select standards (plus the reagent blank), in the 
same acid concentration as the samples, to cover the linear absorption 
range indicated by the instrument manufacturer. Measure the absorbance 
of the blank and standards as in section 8.0. Repeat until good 
agreement is obtained between replicates. Plot absorbance (y-axis) 
versus concentration in g Pb/ml (x-axis). Draw (or compute) a 
straight line through the linear portion of the curve. Do not force the 
calibration curve through zero. Other calibration procedures may be 
used.
    To determine stability of the calibration curve, remeasure--
alternately--one of the following calibration standards for every 10th 
sample analyzed: Concentration ls-thn-eq 1g Pb/ml; 
concentration ls-thn-eq 10 g Pb/ml. If either 
standard deviates by more than 5 percent from the value predicted by the 
calibration curve, recalibrate and repeat the previous 10 analyses.
    10. Calculation.
    10.1 Measured air volume. Calculate the measured air volume at 
Standard Temperature and Pressure as described in Reference 10.
    10.2 Lead concentration. Calculate lead concentration in the air 
sample.



[[Page 60]]


where:

C = Concentration, g Pb/sm3.
g Pb/ml = Lead concentration determined from section 8.
100 ml/strip = Total sample volume.
12 strips = Total useable filter area, 8" x 9". Exposed area of one 
strip, \3/4\" x 7".
Filter = Total area of one strip, \3/4\" x 8".
Fb = Lead concentration of blank filter, g, from 
section 6.1.1.2.3.
VSTP = Air volume from section 10.2.

    11. Quality control.
    \3/4\" x 8" glass fiber filter strips containing 80 to 2000 
g Pb/strip (as lead salts) and blank strips with zero Pb 
content should be used to determine if the method--as being used--has 
any bias. Quality control charts should be established to monitor 
differences between measured and true values. The frequency of such 
checks will depend on the local quality control program.
    To minimize the possibility of generating unreliable data, the user 
should follow practices established for assuring the quality of air 
pollution data, (13) and take part in EPA's semiannual audit program for 
lead analyses.
    12. Trouble shooting.
    1. During extraction of lead by the hot extraction procedure, it is 
important to keep the sample covered so that corrosion products--formed 
on fume hood surfaces which may contain lead--are not deposited in the 
extract.
    2. The sample acid concentration should minimize corrosion of the 
nebulizer. However, different nebulizers may require lower acid 
concentrations. Lower concentrations can be used provided samples and 
standards have the same acid concentration.
    3. Ashing of particulate samples has been found, by EPA and 
contractor laboratories, to be unnecessary in lead analyses by atomic 
absorption. Therefore, this step was omitted from the method.
    4. Filtration of extracted samples, to remove particulate matter, 
was specifically excluded from sample preparation, because some analysts 
have observed losses of lead due to filtration.
    5. If suspended solids should clog the nebulizer during analysis of 
samples, centrifuge the sample to remove the solids.
    13. Authority.
    (Secs. 109 and 301(a), Clean Air Act, as amended (42 U.S.C. 7409, 
7601(a)))
    14. References.
    1. Scott, D. R. et al. ``Atomic Absorption and Optical Emission 
Analysis of NASN Atmospheric Particulate Samples for Lead.'' Envir. Sci. 
and Tech., 10, 877-880 (1976).
    2. Skogerboe, R. K. et al. ``Monitoring for Lead in the 
Environment.'' pp. 57-66, Department of Chemistry, Colorado State 
University, Fort Collins, CO 80523. Submitted to National Science 
Foundation for publications, 1976.
    3. Zdrojewski, A. et al. ``The Accurate Measurement of Lead in 
Airborne Particulates.'' Inter. J. Environ. Anal. Chem., 2, 63-77 
(1972).
    4. Slavin, W., ``Atomic Absorption Spectroscopy.'' Published by 
Interscience Company, New York, NY (1968).
    5. Kirkbright, G. F., and Sargent, M., ``Atomic Absorption and 
Fluorescence Spectroscopy.'' Published by Academic Press, New York, NY 
1974.
    6. Burnham, C. D. et al., ``Determination of Lead in Airborne 
Particulates in Chicago and Cook County, IL, by Atomic Absorption 
Spectroscopy.'' Envir. Sci. and Tech., 3, 472-475 (1969).
    7. ``Proposed Recommended Practices for Atomic Absorption 
Spectrometry.'' ASTM Book of Standards, part 30, pp. 1596-1608 (July 
1973).
    8. Koirttyohann, S. R. and Wen, J. W., ``Critical Study of the APCD-
MIBK Extraction System for Atomic Absorption.'' Anal. Chem., 45, 1986-
1989 (1973).
    9. Collaborative Study of Reference Method for the Determination of 
Suspended Particulates in the Atmosphere (High Volume Method). 
Obtainable from National Technical Information Service, Department of 
Commerce, Port Royal Road, Springfield, VA 22151, as PB-205-891.
    10. [Reserved]
    11. Dubois, L., et al., ``The Metal Content of Urban Air.'' JAPCA, 
16, 77-78 (1966).
    12. EPA Report No. 600/4-77-034, June 1977, ``Los Angeles Catalyst 
Study Symposium.'' Page 223.
    13. Quality Assurance Handbook for Air Pollution Measurement System. 
Volume 1--Principles. EPA-600/9-76-005, March 1976.
    14. Thompson, R. J. et al., ``Analysis of Selected Elements in 
Atmospheric Particulate Matter by Atomic Absorption.'' Atomic Absorption 
Newsletter, 9, No. 3, May-June 1970.
    15. To be published. EPA, QAB, EMSL, RTP, N.C. 27711
    16. Quality Assurance Handbook for Air Pollution Measurement 
Systems. Volume II--Ambient Air Specific Methods. EPA-600/4-77/027a, May 
1977.

[[Page 61]]




[[Page 62]]




(Secs. 109, 301(a) of the Clean Air Act, as amended (42 U.S.C. 7409, 
7601(a)); secs. 110, 301(a) and 319 of the Clean Air Act (42 U.S.C. 
7410, 7601(a), 7619))

[43 FR 46258, Oct. 5, 1978; 44 FR 37915, June 29, 1979, as amended at 46 
FR 44163, Sept. 3, 1981; 52 FR 24664, July 1, 1987]

    Appendix H to Part 50--Interpretation of the 1-Hour Primary and 
       Secondary National Ambient Air Quality Standards for Ozone

                               1. General

    This appendix explains how to determine when the expected number of 
days per calendar year with maximum hourly average concentrations above 
0.12 ppm (235 g/m3) is equal to or less than 1. An 
expanded discussion of these procedures and associated examples are 
contained in the ``Guideline for Interpretation of Ozone Air Quality 
Standards.'' For purposes of clarity in the following discussion, it is 
convenient to use the term ``exceedance'' to describe a daily maximum 
hourly average ozone measurement that is greater than the level of the 
standard. Therefore, the phrase ``expected number of days with maximum 
hourly average ozone concentrations above the level of the standard'' 
may be simply stated as the ``expected number of exceedances.''

[[Page 63]]

    The basic principle in making this determination is relatively 
straightforward. Most of the complications that arise in determining the 
expected number of annual exceedances relate to accounting for 
incomplete sampling. In general, the average number of exceedances per 
calendar year must be less than or equal to 1. In its simplest form, the 
number of exceedances at a monitoring site would be recorded for each 
calendar year and then averaged over the past 3 calendar years to 
determine if this average is less than or equal to 1.

                2. Interpretation of Expected Exceedances

    The ozone standard states that the expected number of exceedances 
per year must be less than or equal to 1. The statistical term 
``expected number'' is basically an arithmetic average. The following 
example explains what it would mean for an area to be in compliance with 
this type of standard. Suppose a monitoring station records a valid 
daily maximum hourly average ozone value for every day of the year 
during the past 3 years. At the end of each year, the number of days 
with maximum hourly concentrations above 0.12 ppm is determined and this 
number is averaged with the results of previous years. As long as this 
average remains ``less than or equal to 1,'' the area is in compliance.

           3. Estimating the Number of Exceedances for a Year

    In general, a valid daily maximum hourly average value may not be 
available for each day of the year, and it will be necessary to account 
for these missing values when estimating the number of exceedances for a 
particular calendar year. The purpose of these computations is to 
determine if the expected number of exceedances per year is less than or 
equal to 1. Thus, if a site has two or more observed exceedances each 
year, the standard is not met and it is not necessary to use the 
procedures of this section to account for incomplete sampling.
    The term ``missing value'' is used here in the general sense to 
describe all days that do not have an associated ozone measurement. In 
some cases, a measurement might actually have been missed but in other 
cases no measurement may have been scheduled for that day. A daily 
maximum ozone value is defined to be the highest hourly ozone value 
recorded for the day. This daily maximum value is considered to be valid 
if 75 percent of the hours from 9:01 a.m. to 9:00 p.m. (LST) were 
measured or if the highest hour is greater than the level of the 
standard.
    In some areas, the seasonal pattern of ozone is so pronounced that 
entire months need not be sampled because it is extremely unlikely that 
the standard would be exceeded. Any such waiver of the ozone monitoring 
requirement would be handled under provisions of 40 CFR, part 58. Some 
allowance should also be made for days for which valid daily maximum 
hourly values were not obtained but which would quite likely have been 
below the standard. Such an allowance introduces a complication in that 
it becomes necessary to define under what conditions a missing value may 
be assumed to have been less than the level of the standard. The 
following criterion may be used for ozone:
    A missing daily maximum ozone value may be assumed to be less than 
the level of the standard if the valid daily maxima on both the 
preceding day and the following day do not exceed 75 percent of the 
level of the standard.
    Let z denote the number of missing daily maximum values that may be 
assumed to be less than the standard. Then the following formula shall 
be used to estimate the expected number of exceedances for the year:
[GRAPHIC] [TIFF OMITTED] TC08NO91.086

    (*Indicates multiplication.)

where:

e = the estimated number of exceedances for the year,
N = the number of required monitoring days in the year,
n = the number of valid daily maxima,
v = the number of daily values above the level of the standard, and
z = the number of days assumed to be less than the standard level.

    This estimated number of exceedances shall be rounded to one decimal 
place (fractional parts equal to 0.05 round up).
    It should be noted that N will be the total number of days in the 
year unless the appropriate Regional Administrator has granted a waiver 
under the provisions of 40 CFR part 58.
    The above equation may be interpreted intuitively in the following 
manner. The estimated number of exceedances is equal to the observed 
number of exceedances (v) plus an increment that accounts for incomplete 
sampling. There were (N-n) missing values for the year but a certain 
number of these, namely z, were assumed to be less than the standard. 
Therefore, (N-n-z) missing values are considered to include possible 
exceedances. The fraction of measured values that are above the level of 
the standard is v/n. It is assumed that this same fraction applies to 
the (N-n-z) missing values and that (v/n)*(N-n-z) of these values would 
also have exceeded the level of the standard.

[44 FR 8220, Feb. 8, 1979, as amended at 62 FR 38895, July 18, 1997]

[[Page 64]]

    Appendix I to Part 50--Interpretation of the 8-Hour Primary and 
       Secondary National Ambient Air Quality Standards for Ozone

    1. General.
    This appendix explains the data handling conventions and 
computations necessary for determining whether the national 8-hour 
primary and secondary ambient air quality standards for ozone specified 
in Sec. 50.10 are met at an ambient ozone air quality monitoring site. 
Ozone is measured in the ambient air by a reference method based on 
appendix D of this part. Data reporting, data handling, and computation 
procedures to be used in making comparisons between reported ozone 
concentrations and the level of the ozone standard are specified in the 
following sections. Whether to exclude, retain, or make adjustments to 
the data affected by stratospheric ozone intrusion or other natural 
events is subject to the approval of the appropriate Regional 
Administrator.
    2. Primary and Secondary Ambient Air Quality Standards for Ozone.
    2.1  Data Reporting and Handling Conventions.
    2.1.1 Computing 8-hour averages. Hourly average concentrations shall 
be reported in parts per million (ppm) to the third decimal place, with 
additional digits to the right being truncated. Running 8-hour averages 
shall be computed from the hourly ozone concentration data for each hour 
of the year and the result shall be stored in the first, or start, hour 
of the 8-hour period. An 8-hour average shall be considered valid if at 
least 75% of the hourly averages for the 8-hour period are available. In 
the event that only 6 (or 7) hourly averages are available, the 8-hour 
average shall be computed on the basis of the hours available using 6 
(or 7) as the divisor. (8-hour periods with three or more missing hours 
shall not be ignored if, after substituting one-half the minimum 
detectable limit for the missing hourly concentrations, the 8-hour 
average concentration is greater than the level of the standard.) The 
computed 8-hour average ozone concentrations shall be reported to three 
decimal places (the insignificant digits to the right of the third 
decimal place are truncated, consistent with the data handling 
procedures for the reported data.)
    2.1.2  Daily maximum 8-hour average concentrations. (a) There are 24 
possible running 8-hour average ozone concentrations for each calendar 
day during the ozone monitoring season. (Ozone monitoring seasons vary 
by geographic location as designated in part 58, appendix D to this 
chapter.) The daily maximum 8-hour concentration for a given calendar 
day is the highest of the 24 possible 8-hour average concentrations 
computed for that day. This process is repeated, yielding a daily 
maximum 8-hour average ozone concentration for each calendar day with 
ambient ozone monitoring data. Because the 8-hour averages are recorded 
in the start hour, the daily maximum 8-hour concentrations from two 
consecutive days may have some hourly concentrations in common. 
Generally, overlapping daily maximum 8-hour averages are not likely, 
except in those non-urban monitoring locations with less pronounced 
diurnal variation in hourly concentrations.
    (b) An ozone monitoring day shall be counted as a valid day if valid 
8-hour averages are available for at least 75% of possible hours in the 
day (i.e., at least 18 of the 24 averages). In the event that less than 
75% of the 8-hour averages are available, a day shall also be counted as 
a valid day if the daily maximum 8-hour average concentration for that 
day is greater than the level of the ambient standard.
    2.2  Primary and Secondary Standard-related Summary Statistic. The 
standard-related summary statistic is the annual fourth-highest daily 
maximum 8-hour ozone concentration, expressed in parts per million, 
averaged over three years. The 3-year average shall be computed using 
the three most recent, consecutive calendar years of monitoring data 
meeting the data completeness requirements described in this appendix. 
The computed 3-year average of the annual fourth-highest daily maximum 
8-hour average ozone concentrations shall be expressed to three decimal 
places (the remaining digits to the right are truncated.)
    2.3 Comparisons with the Primary and Secondary Ozone Standards. (a) 
The primary and secondary ozone ambient air quality standards are met at 
an ambient air quality monitoring site when the 3-year average of the 
annual fourth-highest daily maximum 8-hour average ozone concentration 
is less than or equal to 0.08 ppm. The number of significant figures in 
the level of the standard dictates the rounding convention for comparing 
the computed 3-year average annual fourth-highest daily maximum 8-hour 
average ozone concentration with the level of the standard. The third 
decimal place of the computed value is rounded, with values equal to or 
greater than 5 rounding up. Thus, a computed 3-year average ozone 
concentration of 0.085 ppm is the smallest value that is greater than 
0.08 ppm.
    (b) This comparison shall be based on three consecutive, complete 
calendar years of air quality monitoring data. This requirement is met 
for the three year period at a monitoring site if daily maximum 8-hour 
average concentrations are available for at least 90%, on average, of 
the days during the designated ozone monitoring season, with a minimum 
data completeness in any one year of at least 75% of the designated 
sampling days. When

[[Page 65]]

computing whether the minimum data completeness requirements have been 
met, meteorological or ambient data may be sufficient to demonstrate 
that meteorological conditions on missing days were not conducive to 
concentrations above the level of the standard. Missing days assumed 
less than the level of the standard are counted for the purpose of 
meeting the data completeness requirement, subject to the approval of 
the appropriate Regional Administrator.
    (c) Years with concentrations greater than the level of the standard 
shall not be ignored on the ground that they have less than complete 
data. Thus, in computing the 3-year average fourth maximum 
concentration, calendar years with less than 75% data completeness shall 
be included in the computation if the average annual fourth maximum 8-
hour concentration is greater than the level of the standard.
    (d) Comparisons with the primary and secondary ozone standards are 
demonstrated by examples 1 and 2 in paragraphs (d)(1) and (d) (2) 
respectively as follows:
    (1) As shown in example 1, the primary and secondary standards are 
met at this monitoring site because the 3-year average of the annual 
fourth-highest daily maximum 8-hour average ozone concentrations (i.e., 
0.084 ppm) is less than or equal to 0.08 ppm. The data completeness 
requirement is also met because the average percent of days with valid 
ambient monitoring data is greater than 90%, and no single year has less 
than 75% data completeness.

             Example 1. Ambient monitoring site attaining the primary and secondary ozone standards
----------------------------------------------------------------------------------------------------------------
                                                 1st Highest  2nd Highest  3rd Highest  4th Highest  5th Highest
                                      Percent    Daily Max 8- Daily Max 8- Daily Max 8- Daily Max 8- Daily Max 8-
               Year                  Valid Days   hour Conc.   hour Conc.   hour Conc.   hour Conc.   hour Conc.
                                                    (ppm)        (ppm)        (ppm)        (ppm)        (ppm)
----------------------------------------------------------------------------------------------------------------
1993..............................         100%        0.092        0.091        0.090        0.088        0.085
----------------------------------------------------------------------------------------------------------------
1994..............................          96%        0.090        0.089        0.086        0.084        0.080
----------------------------------------------------------------------------------------------------------------
1995..............................          98%        0.087        0.085        0.083        0.080        0.075
================================================================================================================
    Average.......................          98%
----------------------------------------------------------------------------------------------------------------

    (2) As shown in example 2, the primary and secondary standards are 
not met at this monitoring site because the 3-year average of the 
fourth-highest daily maximum 8-hour average ozone concentrations (i.e., 
0.093 ppm) is greater than 0.08 ppm. Note that the ozone concentration 
data for 1994 is used in these computations, even though the data 
capture is less than 75%, because the average fourth-highest daily 
maximum 8-hour average concentration is greater than 0.08 ppm.

          Example 2. Ambient Monitoring Site Failing to Meet the Primary and Secondary Ozone Standards
----------------------------------------------------------------------------------------------------------------
                                                 1st Highest  2nd Highest  3rd Highest  4th Highest  5th Highest
                                      Percent    Daily Max 8- Daily Max 8- Daily Max 8- Daily Max 8- Daily Max 8-
               Year                  Valid Days   hour Conc.   hour Conc.   hour Conc.   hour Conc.   hour Conc.
                                                    (ppm)        (ppm)        (ppm)        (ppm)        (ppm)
----------------------------------------------------------------------------------------------------------------
1993..............................          96%        0.105        0.103        0.103        0.102        0.102
----------------------------------------------------------------------------------------------------------------
1994..............................          74%        0.090        0.085        0.082        0.080        0.078
----------------------------------------------------------------------------------------------------------------
1995..............................          98%        0.103        0.101        0.101        0.097        0.095
================================================================================================================
    Average.......................          89%
----------------------------------------------------------------------------------------------------------------

    3. Design Values for Primary and Secondary Ambient Air Quality 
Standards for Ozone. The air quality design value at a monitoring site 
is defined as that concentration that when reduced to the level of the 
standard ensures that the site meets the standard. For a concentration-
based standard, the air quality design value is simply the standard-
related test statistic. Thus, for the primary and secondary ozone 
standards, the 3-year average annual fourth-highest daily maximum 8-hour 
average ozone concentration is also the air quality design value for the 
site.

[62 FR 38895, July 18, 1997]

    Appendix J to Part 50--Reference Method for the Determination of 
         Particulate Matter as PM10 in the Atmosphere

    1.0 Applicability.

[[Page 66]]

    1.1 This method provides for the measurement of the mass 
concentration of particulate matter with an aerodynamic diameter less 
than or equal to a nominal 10 micrometers (PM1O) in ambient 
air over a 24-hour period for purposes of determining attainment and 
maintenance of the primary and secondary national ambient air quality 
standards for particulate matter specified in Sec. 50.6 of this chapter. 
The measurement process is nondestructive, and the PM10 
sample can be subjected to subsequent physical or chemical analyses. 
Quality assurance procedures and guidance are provided in part 58, 
appendices A and B, of this chapter and in References 1 and 2.
    2.0 Principle.
    2.1 An air sampler draws ambient air at a constant flow rate into a 
specially shaped inlet where the suspended particulate matter is 
inertially separated into one or more size fractions within the 
PM10 size range. Each size fraction in the PM1O 
size range is then collected on a separate filter over the specified 
sampling period. The particle size discrimination characteristics 
(sampling effectiveness and 50 percent cutpoint) of the sampler inlet 
are prescribed as performance specifications in part 53 of this chapter.
    2.2 Each filter is weighed (after moisture equilibration) before and 
after use to determine the net weight (mass) gain due to collected 
PM10. The total volume of air sampled, corrected to EPA 
reference conditions (25 C, 101.3 kPa), is determined from the measured 
flow rate and the sampling time. The mass concentration of 
PM10 in the ambient air is computed as the total mass of 
collected particles in the PM10 size range divided by the 
volume of air sampled, and is expressed in micrograms per standard cubic 
meter (g/std m\3\). For PM10 samples collected at 
temperatures and pressures significantly different from EPA reference 
conditions, these corrected concentrations sometimes differ 
substantially from actual concentrations (in micrograms per actual cubic 
meter), particularly at high elevations. Although not required, the 
actual PM10 concentration can be calculated from the 
corrected concentration, using the average ambient temperature and 
barometric pressure during the sampling period.
    2.3 A method based on this principle will be considered a reference 
method only if (a) the associated sampler meets the requirements 
specified in this appendix and the requirements in part 53 of this 
chapter, and (b) the method has been designated as a reference method in 
accordance with part 53 of this chapter.
    3.0 Range.
    3.1 The lower limit of the mass concentration range is determined by 
the repeatability of filter tare weights, assuming the nominal air 
sample volume for the sampler. For samplers having an automatic filter-
changing mechanism, there may be no upper limit. For samplers that do 
not have an automatic filter-changing mechanism, the upper limit is 
determined by the filter mass loading beyond which the sampler no longer 
maintains the operating flow rate within specified limits due to 
increased pressure drop across the loaded filter. This upper limit 
cannot be specified precisely because it is a complex function of the 
ambient particle size distribution and type, humidity, filter type, and 
perhaps other factors. Nevertheless, all samplers should be capable of 
measuring 24-hour PM10 mass concentrations of at least 300 
g/std m\3\ while maintaining the operating flow rate within the 
specified limits.
    4.0 Precision.
    4.1 The precision of PM10 samplers must be 5 g/
m\3\ for PM10 concentrations below 80 g/m\3\ and 7 
percent for PM10 concentrations above 80 g/m\3\, as 
required by part 53 of this chapter, which prescribes a test procedure 
that determines the variation in the PM10 concentration 
measurements of identical samplers under typical sampling conditions. 
Continual assessment of precision via collocated samplers is required by 
part 58 of this chapter for PM10 samplers used in certain 
monitoring networks.
    5.0 Accuracy.
    5.1 Because the size of the particles making up ambient particulate 
matter varies over a wide range and the concentration of particles 
varies with particle size, it is difficult to define the absolute 
accuracy of PM10 samplers. Part 53 of this chapter provides a 
specification for the sampling effectiveness of PM10 
samplers. This specification requires that the expected mass 
concentration calculated for a candidate PM10 sampler, when 
sampling a specified particle size distribution, be within 
10 percent of that calculated for an ideal sampler whose 
sampling effectiveness is explicitly specified. Also, the particle size 
for 50 percent sampling effectivensss is required to be 
100.5 micrometers. Other specifications related to accuracy 
apply to flow measurement and calibration, filter media, analytical 
(weighing) procedures, and artifact. The flow rate accuracy of 
PM10 samplers used in certain monitoring networks is required 
by part 58 of this chapter to be assessed periodically via flow rate 
audits.
    6.0 Potential Sources of Error.
    6.1 Volatile Particles. Volatile particles collected on filters are 
often lost during shipment and/or storage of the filters prior to the 
post-sampling weighing \3\. Although shipment or storage of loaded 
filters is sometimes unavoidable, filters should be reweighed as soon as 
practical to minimize these losses.
    6.2 Artifacts. Positive errors in PM10 concentration 
measurements may result from retention of gaseous species on filters 
4, 5. Such errors include the retention of sulfur

[[Page 67]]

dioxide and nitric acid. Retention of sulfur dioxide on filters, 
followed by oxidation to sulfate, is referred to as artifact sulfate 
formation, a phenomenon which increases with increasing filter 
alkalinity \6\. Little or no artifact sulfate formation should occur 
using filters that meet the alkalinity specification in section 7.2.4. 
Artifact nitrate formation, resulting primarily from retention of nitric 
acid, occurs to varying degrees on many filter types, including glass 
fiber, cellulose ester, and many quartz fiber filters 
5, 7, 8, 9, 10. Loss of true atmospheric particulate nitrate 
during or following sampling may also occur due to dissociation or 
chemical reaction. This phenomenon has been observed on 
Teflon filters \8\ and inferred for quartz fiber filters 
11, 12. The magnitude of nitrate artifact errors in 
PM10 mass concentration measurements will vary with location 
and ambient temperature; however, for most sampling locations, these 
errors are expected to be small.
    6.3 Humidity. The effects of ambient humidity on the sample are 
unavoidable. The filter equilibration procedure in section 9.0 is 
designed to minimize the effects of moisture on the filter medium.
    6.4 Filter Handling. Careful handling of filters between presampling 
and postsampling weighings is necessary to avoid errors due to damaged 
filters or loss of collected particles from the filters. Use of a filter 
cartridge or cassette may reduce the magnitude of these errors. Filters 
must also meet the integrity specification in section 7.2.3.
    6.5 Flow Rate Variation. Variations in the sampler's operating flow 
rate may alter the particle size discrimination characteristics of the 
sampler inlet. The magnitude of this error will depend on the 
sensitivity of the inlet to variations in flow rate and on the particle 
distribution in the atmosphere during the sampling period. The use of a 
flow control device (section 7.1.3) is required to minimize this error.
    6.6 Air Volume Determination. Errors in the air volume determination 
may result from errors in the flow rate and/or sampling time 
measurements. The flow control device serves to minimize errors in the 
flow rate determination, and an elapsed time meter (section 7.1.5) is 
required to minimize the error in the sampling time measurement.
    7.0 Apparatus.
    7.1 PM10 Sampler.
    7.1.1 The sampler shall be designed to:
    a. Draw the air sample into the sampler inlet and through the 
particle collection filter at a uniform face velocity.
    b. Hold and seal the filter in a horizontal position so that sample 
air is drawn downward through the filter.
    c. Allow the filter to be installed and removed conveniently.
    d. Protect the filter and sampler from precipitation and prevent 
insects and other debris from being sampled.
    e. Minimize air leaks that would cause error in the measurement of 
the air volume passing through the filter.
    f. Discharge exhaust air at a sufficient distance from the sampler 
inlet to minimize the sampling of exhaust air.
    g. Minimize the collection of dust from the supporting surface.
    7.1.2 The sampler shall have a sample air inlet system that, when 
operated within a specified flow rate range, provides particle size 
discrimination characteristics meeting all of the applicable performance 
specifications prescribed in part 53 of this chapter. The sampler inlet 
shall show no significant wind direction dependence. The latter 
requirement can generally be satisfied by an inlet shape that is 
circularly symmetrical about a vertical axis.
    7.1.3 The sampler shall have a flow control device capable of 
maintaining the sampler's operating flow rate within the flow rate 
limits specified for the sampler inlet over normal variations in line 
voltage and filter pressure drop.
    7.1.4 The sampler shall provide a means to measure the total flow 
rate during the sampling period. A continuous flow recorder is 
recommended but not required. The flow measurement device shall be 
accurate to 2 percent.
    7.1.5 A timing/control device capable of starting and stopping the 
sampler shall be used to obtain a sample collection period of 24 
1 hr (1,440 60 min). An elapsed time meter, 
accurate to within 15 minutes, shall be used to measure 
sampling time. This meter is optional for samplers with continuous flow 
recorders if the sampling time measurement obtained by means of the 
recorder meets the 15 minute accuracy specification.
    7.1.6 The sampler shall have an associated operation or instruction 
manual as required by part 53 of this chapter which includes detailed 
instructions on the calibration, operation, and maintenance of the 
sampler.
    7.2 Filters.
    7.2.1 Filter Medium. No commercially available filter medium is 
ideal in all respects for all samplers. The user's goals in sampling 
determine the relative importance of various filter characteristics 
(e.g., cost, ease of handling, physical and chemical characteristics, 
etc.) and, consequently, determine the choice among acceptable filters. 
Furthermore, certain types of filters may not be suitable for use with 
some samplers, particularly under heavy loading conditions (high mass 
concentrations), because of high or rapid increase in the filter flow 
resistance that would exceed the capability of the sampler's flow 
control device. However, samplers equipped with automatic filter-
changing

[[Page 68]]

mechanisms may allow use of these types of filters. The specifications 
given below are minimum requirements to ensure acceptability of the 
filter medium for measurement of PM10 mass concentrations. 
Other filter evaluation criteria should be considered to meet individual 
sampling and analysis objectives.
    7.2.2 Collection Efficiency. 99 percent, as measured by 
the DOP test (ASTM-2986) with 0.3 m particles at the sampler's 
operating face velocity.
    7.2.3 Integrity. 5 g/m\3\ (assuming sampler's 
nominal 24-hour air sample volume). Integrity is measured as the 
PM10 concentration equivalent corresponding to the average 
difference between the initial and the final weights of a random sample 
of test filters that are weighed and handled under actual or simulated 
sampling conditions, but have no air sample passed through them (i.e., 
filter blanks). As a minimum, the test procedure must include initial 
equilibration and weighing, installation on an inoperative sampler, 
removal from the sampler, and final equilibration and weighing.
    7.2.4 Alkalinity. <25 microequivalents/gram of filter, as measured 
by the procedure given in Reference 13 following at least two months 
storage in a clean environment (free from contamination by acidic gases) 
at room temperature and humidity.
    7.3 Flow Rate Transfer Standard. The flow rate transfer standard 
must be suitable for the sampler's operating flow rate and must be 
calibrated against a primary flow or volume standard that is traceable 
to the National Bureau of Standards (NBS). The flow rate transfer 
standard must be capable of measuring the sampler's operating flow rate 
with an accuracy of 2 percent.
    7.4 Filter Conditioning Environment.
    7.4.1 Temperature range: 15 to 30 C.
    7.4.2 Temperature control: 3 C.
    7.4.3 Humidity range: 20% to 45% RH.
    7.4.4 Humidity control: 5% RH.
    7.5 Analytical Balance. The analytical balance must be suitable for 
weighing the type and size of filters required by the sampler. The range 
and sensitivity required will depend on the filter tare weights and mass 
loadings. Typically, an analytical balance with a sensitivity of 0.1 mg 
is required for high volume samplers (flow rates >0.5 m\3\/min). Lower 
volume samplers (flow rates <0.5 m\3\/min) will require a more sensitive 
balance.
    8.0 Calibration.
    8.1 General Requirements.
    8.1.1 Calibration of the sampler's flow measurement device is 
required to establish traceability of subsequent flow measurements to a 
primary standard. A flow rate transfer standard calibrated against a 
primary flow or volume standard shall be used to calibrate or verify the 
accuracy of the sampler's flow measurement device.
    8.1.2 Particle size discrimination by inertial separation requires 
that specific air velocities be maintained in the sampler's air inlet 
system. Therefore, the flow rate through the sampler's inlet must be 
maintained throughout the sampling period within the design flow rate 
range specified by the manufacturer. Design flow rates are specified as 
actual volumetric flow rates, measured at existing conditions of 
temperature and pressure (Qa). In contrast, mass 
concentrations of PM10 are computed using flow rates 
corrected to EPA reference conditions of temperature and pressure 
(Qstd).
    8.2 Flow Rate Calibration Procedure.
    8.2.1 PM10 samplers employ various types of flow control 
and flow measurement devices. The specific procedure used for flow rate 
calibration or verification will vary depending on the type of flow 
controller and flow indicator employed. Calibration in terms of actual 
volumetric flow rates (Qa) is generally recommended, but 
other measures of flow rate (e.g., Qstd) may be used provided 
the requirements of section 8.1 are met. The general procedure given 
here is based on actual volumetric flow units (Qa) and serves 
to illustrate the steps involved in the calibration of a PM10 
sampler. Consult the sampler manufacturer's instruction manual and 
Reference 2 for specific guidance on calibration. Reference 14 provides 
additional information on the use of the commonly used measures of flow 
rate and their interrelationships.
    8.2.2 Calibrate the flow rate transfer standard against a primary 
flow or volume standard traceable to NBS. Establish a calibration 
relationship (e.g., an equation or family of curves) such that 
traceability to the primary standard is accurate to within 2 percent 
over the expected range of ambient conditions (i.e., temperatures and 
pressures) under which the transfer standard will be used. Recalibrate 
the transfer standard periodically.
    8.2.3 Following the sampler manufacturer's instruction manual, 
remove the sampler inlet and connect the flow rate transfer standard to 
the sampler such that the transfer standard accurately measures the 
sampler's flow rate. Make sure there are no leaks between the transfer 
standard and the sampler.
    8.2.4 Choose a minimum of three flow rates (actual m\3\/min), spaced 
over the acceptable flow rate range specified for the inlet (see 7.1.2) 
that can be obtained by suitable adjustment of the sampler flow rate. In 
accordance with the sampler manufacturer's instruction manual, obtain or 
verify the calibration relationship between the flow rate (actual m\3\/
min) as indicated by the transfer standard and the sampler's flow 
indicator response. Record the ambient temperature and barometric 
pressure. Temperature and pressure corrections to subsequent flow 
indicator readings may be required for certain types of

[[Page 69]]

flow measurement devices. When such corrections are necessary, 
correction on an individual or daily basis is preferable. However, 
seasonal average temperature and average barometric pressure for the 
sampling site may be incorporated into the sampler calibration to avoid 
daily corrections. Consult the sampler manufacturer's instruction manual 
and Reference 2 for additional guidance.
    8.2.5 Following calibration, verify that the sampler is operating at 
its design flow rate (actual m\3\/min) with a clean filter in place.
    8.2.6 Replace the sampler inlet.
    9.0 Procedure.
    9.1 The sampler shall be operated in accordance with the specific 
guidance provided in the sampler manufacturer's instruction manual and 
in Reference 2. The general procedure given here assumes that the 
sampler's flow rate calibration is based on flow rates at ambient 
conditions (Qa) and serves to illustrate the steps involved 
in the operation of a PM10 sampler.
    9.2 Inspect each filter for pinholes, particles, and other 
imperfections. Establish a filter information record and assign an 
identification number to each filter.
    9.3 Equilibrate each filter in the conditioning environment (see 
7.4) for at least 24 hours.
    9.4 Following equilibration, weigh each filter and record the 
presampling weight with the filter identification number.
    9.5 Install a preweighed filter in the sampler following the 
instructions provided in the sampler manufacturer's instruction manual.
    9.6 Turn on the sampler and allow it to establish run-temperature 
conditions. Record the flow indicator reading and, if needed, the 
ambient temperature and barometric pressure. Determine the sampler flow 
rate (actual m\3\/min) in accordance with the instructions provided in 
the sampler manufacturer's instruction manual. NOTE.--No onsite 
temperature or pressure measurements are necessary if the sampler's flow 
indicator does not require temperature or pressure corrections or if 
seasonal average temperature and average barometric pressure for the 
sampling site are incorporated into the sampler calibration (see step 
8.2.4). If individual or daily temperature and pressure corrections are 
required, ambient temperature and barometric pressure can be obtained by 
on-site measurements or from a nearby weather station. Barometric 
pressure readings obtained from airports must be station pressure, not 
corrected to sea level, and may need to be corrected for differences in 
elevation between the sampling site and the airport.
    9.7 If the flow rate is outside the acceptable range specified by 
the manufacturer, check for leaks, and if necessary, adjust the flow 
rate to the specified setpoint. Stop the sampler.
    9.8 Set the timer to start and stop the sampler at appropriate 
times. Set the elapsed time meter to zero or record the initial meter 
reading.
    9.9 Record the sample information (site location or identification 
number, sample date, filter identification number, and sampler model and 
serial number).
    9.10 Sample for 241 hours.
    9.11 Determine and record the average flow rate (Qa) in 
actual m\3\/min for the sampling period in accordance with the 
instructions provided in the sampler manufacturer's instruction manual. 
Record the elapsed time meter final reading and, if needed, the average 
ambient temperature and barometric pressure for the sampling period (see 
note following step 9.6).
    9.12 Carefully remove the filter from the sampler, following the 
sampler manufacturer's instruction manual. Touch only the outer edges of 
the filter.
    9.13 Place the filter in a protective holder or container (e.g., 
petri dish, glassine envelope, or manila folder).
    9.14 Record any factors such as meteorological conditions, 
construction activity, fires or dust storms, etc., that might be 
pertinent to the measurement on the filter information record.
    9.15 Transport the exposed sample filter to the filter conditioning 
environment as soon as possible for equilibration and subsequent 
weighing.
    9.16 Equilibrate the exposed filter in the conditioning environment 
for at least 24 hours under the same temperature and humidity conditions 
used for presampling filter equilibration (see 9.3).
    9.17 Immediately after equilibration, reweigh the filter and record 
the postsampling weight with the filter identification number.
    10.0 Sampler Maintenance.
    10.1 The PM10 sampler shall be maintained in strict 
accordance with the maintenance procedures specified in the sampler 
manufacturer's instruction manual.
    11.0 Calculations.
    11.1 Calculate the average flow rate over the sampling period 
corrected to EPA reference conditions as Qstd. When the 
sampler's flow indicator is calibrated in actual volumetric units 
(Qa), Qstd is calculated as:

Qstd=Qa x (Pav/
Tav)(Tstd/Pstd)

where

Qstd = average flow rate at EPA reference conditions, std 
m\3\/min;
Qa = average flow rate at ambient conditions, m\3\/min;
Pav = average barometric pressure during the sampling period 
or average barometric pressure for the sampling site, kPa (or mm Hg);
Tav = average ambient temperature during the sampling period 
or seasonal average

[[Page 70]]

ambient temperature for the sampling site, K;
Tstd = standard temperature, defined as 298 K;
Pstd = standard pressure, defined as 101.3 kPa (or 760 mm 
Hg).

    11.2 Calculate the total volume of air sampled as:

Vstd = Qstd x t

where

Vstd = total air sampled in standard volume units, std m\3\;
t = sampling time, min.

    11.3 Calculate the PM10 concentration as:

PM10 = (Wf-Wi) x 10\6\/Vstd

where

PM10 = mass concentration of PM10, g/std 
m\3\;
Wf, Wi = final and initial weights of filter 
collecting PM1O particles, g;
10\6\ = conversion of g to g.

    Note: If more than one size fraction in the PM10 size 
range is collected by the sampler, the sum of the net weight gain by 
each collection filter [(Wf-Wi)] is used 
to calculate the PM10 mass concentration.
    12.0 References.
    1. Quality Assurance Handbook for Air Pollution Measurement Systems, 
Volume I, Principles. EPA-600/9-76-005, March 1976. Available from CERI, 
ORD Publications, U.S. Environmental Protection Agency, 26 West St. 
Clair Street, Cincinnati, OH 45268.
    2. Quality Assurance Handbook for Air Pollution Measurement Systems, 
Volume II, Ambient Air Specific Methods. EPA-600/4-77-027a, May 1977. 
Available from CERI, ORD Publications, U.S. Environmental Protection 
Agency, 26 West St. Clair Street, Cincinnati, OH 45268.
    3. Clement, R.E., and F.W. Karasek. Sample Composition Changes in 
Sampling and Analysis of Organic Compounds in Aerosols. Int. J. Environ. 
Analyt. Chem., 7:109, 1979.
    4. Lee, R.E., Jr., and J. Wagman. A Sampling Anomaly in the 
Determination of Atmospheric Sulfate Concentration. Amer. Ind. Hyg. 
Assoc. J., 27:266, 1966.
    5. Appel, B.R., S.M. Wall, Y. Tokiwa, and M. Haik. Interference 
Effects in Sampling Particulate Nitrate in Ambient Air. Atmos. Environ., 
13:319, 1979.
    6. Coutant, R.W. Effect of Environmental Variables on Collection of 
Atmospheric Sulfate. Environ. Sci. Technol., 11:873, 1977.
    7. Spicer, C.W., and P. Schumacher. Interference in Sampling 
Atmospheric Particulate Nitrate. Atmos. Environ., 11:873, 1977.
    8. Appel, B.R., Y. Tokiwa, and M. Haik. Sampling of Nitrates in 
Ambient Air. Atmos. Environ., 15:283, 1981.
    9. Spicer, C.W., and P.M. Schumacher. Particulate Nitrate: 
Laboratory and Field Studies of Major Sampling Interferences. Atmos. 
Environ., 13:543, 1979.
    10. Appel, B.R. Letter to Larry Purdue, U.S. EPA, Environmental 
Monitoring and Support Laboratory. March 18, 1982, Docket No. A-82-37, 
II-I-1.
    11. Pierson, W.R., W.W. Brachaczek, T.J. Korniski, T.J. Truex, and 
J.W. Butler. Artifact Formation of Sulfate, Nitrate, and Hydrogen Ion on 
Backup Filters: Allegheny Mountain Experiment. J. Air Pollut. Control 
Assoc., 30:30, 1980.
    12. Dunwoody, C.L. Rapid Nitrate Loss From PM10 Filters. 
J. Air Pollut. Control Assoc., 36:817, 1986.
    13. Harrell, R.M. Measuring the Alkalinity of Hi-Vol Air Filters. 
EMSL/RTP-SOP-QAD-534, October 1985. Available from the U.S. 
Environmental Protection Agency, EMSL/QAD, Research Triangle Park, NC 
27711.
    14. Smith, F., P.S. Wohlschlegel, R.S.C. Rogers, and D.J. Mulligan. 
Investigation of Flow Rate Calibration Procedures Associated With the 
High Volume Method for Determination of Suspended Particulates. EPA-600/
4-78-047, U.S. Environmental Protection Agency, Research Triangle Park, 
NC 27711, 1978.

[52 FR 24664, July 1, 1987; 52 FR 29467, Aug. 7, 1987]

   Appendix K to Part 50--Interpretation of the National Ambient Air 
                Quality Standards for Particulate Matter

    1.0  General.
    (a) This appendix explains the computations necessary for analyzing 
particulate matter data to determine attainment of the 24-hour and 
annual standards specified in 40 CFR 50.6. For the primary and secondary 
standards, particulate matter is measured in the ambient air as 
PM10 (particles with an aerodynamic diameter less than or 
equal to a nominal 10 micrometers) by a reference method based on 
appendix J of this part and designated in accordance with part 53 of 
this chapter, or by an equivalent method designated in accordance with 
part 53 of this chapter. The required frequency of measurements is 
specified in part 58 of this chapter.
    (b) The terms used in this appendix are defined as follows:
    Average refers to an arithmetic mean. All particulate matter 
standards are expressed in terms of expected annual values: Expected 
number of exceedances per year for the 24-hour standards and expected 
annual arithmetic mean for the annual standards.
    Daily value for PM10 refers to the 24-hour average 
concentration of PM10 calculated or measured from midnight to 
midnight (local time).
    Exceedance means a daily value that is above the level of the 24-
hour standard after

[[Page 71]]

rounding to the nearest 10 g/m\3\ (i.e., values ending in 5 or 
greater are to be rounded up).
    Expected annual value is the number approached when the annual 
values from an increasing number of years are averaged, in the absence 
of long-term trends in emissions or meteorological conditions.
    Year refers to a calendar year.
    (c) Although the discussion in this appendix focuses on monitored 
data, the same principles apply to modeling data, subject to EPA 
modeling guidelines.
    2.0  Attainment Determinations.
    2.1  24-Hour Primary and Secondary Standards.
    (a) Under 40 CFR 50.6(a) the 24-hour primary and secondary standards 
are attained when the expected number of exceedances per year at each 
monitoring site is less than or equal to one. In the simplest case, the 
number of expected exceedances at a site is determined by recording the 
number of exceedances in each calendar year and then averaging them over 
the past 3 calendar years. Situations in which 3 years of data are not 
available and possible adjustments for unusual events or trends are 
discussed in sections 2.3 and 2.4 of this appendix. Further, when data 
for a year are incomplete, it is necessary to compute an estimated 
number of exceedances for that year by adjusting the observed number of 
exceedances. This procedure, performed by calendar quarter, is described 
in section 3.0 of this appendix. The expected number of exceedances is 
then estimated by averaging the individual annual estimates for the past 
3 years.
    (b) The comparison with the allowable expected exceedance rate of 
one per year is made in terms of a number rounded to the nearest tenth 
(fractional values equal to or greater than 0.05 are to be rounded up; 
e.g., an exceedance rate of 1.05 would be rounded to 1.1, which is the 
lowest rate for nonattainment).
    2.2  Annual Primary and Secondary Standards. Under 40 CFR 50.6(b), 
the annual primary and secondary standards are attained when the 
expected annual arithmetic mean PM10 concentration is less 
than or equal to the level of the standard. In the simplest case, the 
expected annual arithmetic mean is determined by averaging the annual 
arithmetic mean PM10 concentrations for the past 3 calendar 
years. Because of the potential for incomplete data and the possible 
seasonality in PM10 concentrations, the annual mean shall be 
calculated by averaging the four quarterly means of 
PM10 concentrations within the calendar year. The equations 
for calculating the annual arithmetic mean are given in section 4.0 of 
this appendix. Situations in which 3 years of data are not available and 
possible adjustments for unusual events or trends are discussed in 
sections 2.3 and 2.4 of this appendix. The expected annual arithmetic 
mean is rounded to the nearest 1 g/m\3\ before comparison with 
the annual standards (fractional values equal to or greater than 0.5 are 
to be rounded up).
    2.3  Data Requirements.
    (a) 40 CFR 58.13 specifies the required minimum frequency of 
sampling for PM10. For the purposes of making comparisons 
with the particulate matter standards, all data produced by National Air 
Monitoring Stations (NAMS), State and Local Air Monitoring Stations 
(SLAMS) and other sites submitted to EPA in accordance with the part 58 
requirements must be used, and a minimum of 75 percent of the scheduled 
PM10 samples per quarter are required.
    (b) To demonstrate attainment of either the annual or 24-hour 
standards at a monitoring site, the monitor must provide sufficient data 
to perform the required calculations of sections 3.0 and 4.0 of this 
appendix. The amount of data required varies with the sampling 
frequency, data capture rate and the number of years of record. In all 
cases, 3 years of representative monitoring data that meet the 75 
percent criterion of the previous paragraph should be utilized, if 
available, and would suffice. More than 3 years may be considered, if 
all additional representative years of data meeting the 75 percent 
criterion are utilized. Data not meeting these criteria may also suffice 
to show attainment; however, such exceptions will have to be approved by 
the appropriate Regional Administrator in accordance with EPA guidance.
    (c) There are less stringent data requirements for showing that a 
monitor has failed an attainment test and thus has recorded a violation 
of the particulate matter standards. Although it is generally necessary 
to meet the minimum 75 percent data capture requirement per quarter to 
use the computational equations described in sections 3.0 and 4.0 of 
this appendix, this criterion does not apply when less data is 
sufficient to unambiguously establish nonattainment. The following 
examples illustrate how nonattainment can be demonstrated when a site 
fails to meet the completeness criteria. Nonattainment of the 24-hour 
primary standards can be established by the observed annual number of 
exceedances (e.g., four observed exceedances in a single year), or by 
the estimated number of exceedances derived from the observed number of 
exceedances and the required number of scheduled samples (e.g., two 
observed exceedances with every other day sampling). Nonattainment of 
the annual standards can be demonstrated on the basis of quarterly mean 
concentrations developed from observed data combined with one-half the 
minimum detectable concentration substituted for missing values. In both 
cases, expected annual values must exceed the levels allowed by the 
standards.
    2.4  Adjustment for Exceptional Events and Trends.

[[Page 72]]

    (a) An exceptional event is an uncontrollable event caused by 
natural sources of particulate matter or an event that is not expected 
to recur at a given location. Inclusion of such a value in the 
computation of exceedances or averages could result in inappropriate 
estimates of their respective expected annual values. To reduce the 
effect of unusual events, more than 3 years of representative data may 
be used. Alternatively, other techniques, such as the use of statistical 
models or the use of historical data could be considered so that the 
event may be discounted or weighted according to the likelihood that it 
will recur. The use of such techniques is subject to the approval of the 
appropriate Regional Administrator in accordance with EPA guidance.
    (b) In cases where long-term trends in emissions and air quality are 
evident, mathematical techniques should be applied to account for the 
trends to ensure that the expected annual values are not inappropriately 
biased by unrepresentative data. In the simplest case, if 3 years of 
data are available under stable emission conditions, this data should be 
used. In the event of a trend or shift in emission patterns, either the 
most recent representative year(s) could be used or statistical 
techniques or models could be used in conjunction with previous years of 
data to adjust for trends. The use of less than 3 years of data, and any 
adjustments are subject to the approval of the appropriate Regional 
Administrator in accordance with EPA guidance.
    3.0  Computational Equations for the 24-hour Standards.
    3.1  Estimating Exceedances for a Year.
    (a) If PM10 sampling is scheduled less frequently than 
every day, or if some scheduled samples are missed, a PM10 
value will not be available for each day of the year. To account for the 
possible effect of incomplete data, an adjustment must be made to the 
data collected at each monitoring location to estimate the number of 
exceedances in a calendar year. In this adjustment, the assumption is 
made that the fraction of missing values that would have exceeded the 
standard level is identical to the fraction of measured values above 
this level. This computation is to be made for all sites that are 
scheduled to monitor throughout the entire year and meet the minimum 
data requirements of section 2.3 of this appendix. Because of possible 
seasonal imbalance, this adjustment shall be applied on a quarterly 
basis. The estimate of the expected number of exceedances for the 
quarter is equal to the observed number of exceedances plus an increment 
associated with the missing data. The following equation must be used 
for these computations:

                               Equation 1
[GRAPHIC] [TIFF OMITTED] TR18JY97.180

where:

eq = the estimated number of exceedances for calendar quarter 
q;
vq = the observed number of exceedances for calendar quarter 
q;
Nq = the number of days in calendar quarter q;
nq = the number of days in calendar quarter q with 
PM10 data; and
q = the index for calendar quarter, q=1, 2, 3 or 4.

    (b) The estimated number of exceedances for a calendar quarter must 
be rounded to the nearest hundredth (fractional values equal to or 
greater than 0.005 must be rounded up).
    (c) The estimated number of exceedances for the year, e, is the sum 
of the estimates for each calendar quarter.

                               Equation 2
[GRAPHIC] [TIFF OMITTED] TR18JY97.181

    (d) The estimated number of exceedances for a single year must be 
rounded to one decimal place (fractional values equal to or greater than 
0.05 are to be rounded up). The expected number of exceedances is then 
estimated by averaging the individual annual estimates for the most 
recent 3 or more representative years of data. The expected number of 
exceedances must be rounded to one decimal place (fractional values 
equal to or greater than 0.05 are to be rounded up).
    (e) The adjustment for incomplete data will not be necessary for 
monitoring or modeling data which constitutes a complete record, i.e., 
365 days per year.
    (f) To reduce the potential for overestimating the number of 
expected exceedances, the correction for missing data will not be 
required for a calendar quarter in which the first observed exceedance 
has occurred if:
    (1) There was only one exceedance in the calendar quarter;
    (2) Everyday sampling is subsequently initiated and maintained for 4 
calendar quarters in accordance with 40 CFR 58.13; and
    (3) Data capture of 75 percent is achieved during the required 
period of everyday sampling. In addition, if the first exceedance is 
observed in a calendar quarter in which the monitor is already sampling 
every day, no adjustment for missing data will be made to the first 
exceedance if a 75 percent data capture rate was achieved in the quarter 
in which it was observed.

[[Page 73]]

                                Example 1

    a. During a particular calendar quarter, 39 out of a possible 92 
samples were recorded, with one observed exceedance of the 24-hour 
standard. Using Equation 1, the estimated number of exceedances for the 
quarter is:

eq=1 x 92/39=2.359 or 2.36.

    b. If the estimated exceedances for the other 3 calendar quarters in 
the year were 2.30, 0.0 and 0.0, then, using Equation 2, the estimated 
number of exceedances for the year is 2.36=2.30=0.0=0.0 which equals 
4.66 or 4.7. If no exceedances were observed for the 2 previous years, 
then the expected number of exceedances is estimated by: (1/
3) x (4.7=0=0)=1.57 or 1.6. Since 1.6 exceeds the allowable number of 
expected exceedances, this monitoring site would fail the attainment 
test.

                                Example 2

    In this example, everyday sampling was initiated following the first 
observed exceedance as required by 40 CFR 58.13. Accordingly, the first 
observed exceedance would not be adjusted for incomplete sampling. 
During the next three quarters, 1.2 exceedances were estimated. In this 
case, the estimated exceedances for the year would be 1.0=1.2=0.0=0.0 
which equals 2.2. If, as before, no exceedances were observed for the 
two previous years, then the estimated exceedances for the 3-year period 
would then be (1/3) x (2.2=0.0=0.0)=0.7, and the monitoring site would 
not fail the attainment test.
    3.2 Adjustments for Non-Scheduled Sampling Days.
    (a) If a systematic sampling schedule is used and sampling is 
performed on days in addition to the days specified by the systematic 
sampling schedule, e.g., during episodes of high pollution, then an 
adjustment must be made in the eqution for the estimation of 
exceedances. Such an adjustment is needed to eliminate the bias in the 
estimate of the quarterly and annual number of exceedances that would 
occur if the chance of an exceedance is different for scheduled than for 
non-scheduled days, as would be the case with episode sampling.
    (b) The required adjustment treats the systematic sampling schedule 
as a stratified sampling plan. If the period from one scheduled sample 
until the day preceding the next scheduled sample is defined as a 
sampling stratum, then there is one stratum for each scheduled sampling 
day. An average number of observed exceedances is computed for each of 
these sampling strata. With nonscheduled sampling days, the estimated 
number of exceedances is defined as:

                               Equation 3
[GRAPHIC] [TIFF OMITTED] TR18JY97.182

where:

eq = the estimated number of exceedances for the quarter;
Nq = the number of days in the quarter;
mq = the number of strata with samples during the quarter;
vj = the number of observed exceedances in stratum j; and
kj = the number of actual samples in stratum j.

    (c) Note that if only one sample value is recorded in each stratum, 
then Equation 3 reduces to Equation 1.

                                Example 3

    A monitoring site samples according to a systematic sampling 
schedule of one sample every 6 days, for a total of 15 scheduled samples 
in a quarter out of a total of 92 possible samples. During one 6-day 
period, potential episode levels of PM10 were suspected, so 5 
additional samples were taken. One of the regular scheduled samples was 
missed, so a total of 19 samples in 14 sampling strata were measured. 
The one 6-day sampling stratum with 6 samples recorded 2 exceedances. 
The remainder of the quarter with one sample per stratum recorded zero 
exceedances. Using Equation 3, the estimated number of exceedances for 
the quarter is:

eq=(92/14) x (2/6=0=. . .=0)=2.19.

    4.0 Computational Equations for Annual Standards.
    4.1 Calculation of the Annual Arithmetic Mean. (a) An annual 
arithmetic mean value for PM10 is determined by averaging the 
quarterly means for the 4 calendar quarters of the year. The following 
equation is to be used for calculation of the mean for a calendar 
quarter:

                               Equation 4
[GRAPHIC] [TIFF OMITTED] TR18JY97.183

where:

xq = the quarterly mean concentration for quarter q, q=1, 2, 
3, or 4,
nq = the number of samples in the quarter, and
xi = the ith concentration value recorded in the quarter.

    (b) The quarterly mean, expressed in g/m\3\, must be 
rounded to the nearest tenth (fractional values of 0.05 should be 
rounded up).

[[Page 74]]

    (c) The annual mean is calculated by using the following equation:

                               Equation 5
[GRAPHIC] [TIFF OMITTED] TR18JY97.184

where:

x = the annual mean; and
xq = the mean for calendar quarter q.

    (d) The average of quarterly means must be rounded to the nearest 
tenth (fractional values of 0.05 should be rounded up).
    (e) The use of quarterly averages to compute the annual average will 
not be necessary for monitoring or modeling data which results in a 
complete record, i.e., 365 days per year.
    (f) The expected annual mean is estimated as the average of three or 
more annual means. This multi-year estimate, expressed in g/
m\3\, shall be rounded to the nearest integer for comparison with the 
annual standard (fractional values of 0.5 should be rounded up).

                                Example 4

    Using Equation 4, the quarterly means are calculated for each 
calendar quarter. If the quarterly means are 52.4, 75.3, 82.1, and 63.2 
g/m \3\, then the annual mean is:

x = (1/4) x (52.4=75.3=82.1=63.2) = 68.25 or 68.3.

    4.2 Adjustments for Non-scheduled Sampling Days. (a) An adjustment 
in the calculation of the annual mean is needed if sampling is performed 
on days in addition to the days specified by the systematic sampling 
schedule. For the same reasons given in the discussion of estimated 
exceedances, under section 3.2 of this appendix, the quarterly averages 
would be calculated by using the following equation:

                               Equation 6
[GRAPHIC] [TIFF OMITTED] TR18JY97.185

where:

xq = the quarterly mean concentration for quarter q, q=1, 2, 
3, or 4;
xij = the ith concentration value recorded in stratum j;
kj = the number of actual samples in stratum j; and
mq = the number of strata with data in the quarter.

    (b) If one sample value is recorded in each stratum, Equation 6 
reduces to a simple arithmetic average of the observed values as 
described by Equation 4.

                                Example 5

    a. During one calendar quarter, 9 observations were recorded. These 
samples were distributed among 7 sampling strata, with 3 observations in 
one stratum. The concentrations of the 3 observations in the single 
stratum were 202, 242, and 180 g/m\3\. The remaining 6 observed 
concentrations were 55, 68, 73, 92, 120, and 155 g/m\3\. 
Applying the weighting factors specified in Equation 6, the quarterly 
mean is:

xq = (1/7)  x  [(1/3)  x  (202 = 242 = 180) = 155 = 68 = 73 = 
92 = 120 = 155] = 110.1

    b. Although 24-hour measurements are rounded to the nearest 10 
g/m\3\ for determinations of exceedances of the 24-hour 
standard, note that these values are rounded to the nearest 1 
g/m\3\ for the calculation of means.

[62 FR 38712, July 18, 1997]

 Appendix L to Part 50--Reference Method for the Determination of Fine 
        Particulate Matter as PM2.5 in the Atmosphere

    1.0 Applicability.
    1.1 This method provides for the measurement of the mass 
concentration of fine particulate matter having an aerodynamic diameter 
less than or equal to a nominal 2.5 micrometers (PM2.5) in 
ambient air over a 24-hour period for purposes of determining whether 
the primary and secondary national ambient air quality standards for 
fine particulate matter specified in Sec. 50.7 of this part are met. The 
measurement process is considered to be nondestructive, and the 
PM2.5 sample obtained can be subjected to subsequent physical 
or chemical analyses. Quality assessment procedures are provided in part 
58, appendix A of this chapter, and quality assurance guidance are 
provided in references 1, 2, and 3 in section 13.0 of this appendix.
    1.2 This method will be considered a reference method for purposes 
of part 58 of this chapter only if:
    (a) The associated sampler meets the requirements specified in this 
appendix and the applicable requirements in part 53 of this chapter, and
    (b) The method and associated sampler have been designated as a 
reference method in accordance with part 53 of this chapter.
    1.3 PM2.5 samplers that meet nearly all specifications 
set forth in this method but have minor deviations and/or modifications 
of the reference method sampler will be designated as ``Class I'' 
equivalent methods for PM2.5 in accordance with part 53 of 
this chapter.
    2.0 Principle.
    2.1 An electrically powered air sampler draws ambient air at a 
constant volumetric flow rate into a specially shaped inlet and

[[Page 75]]

through an inertial particle size separator (impactor) where the 
suspended particulate matter in the PM2.5 size range is 
separated for collection on a polytetrafluoroethylene (PTFE) filter over 
the specified sampling period. The air sampler and other aspects of this 
reference method are specified either explicitly in this appendix or 
generally with reference to other applicable regulations or quality 
assurance guidance.
    2.2 Each filter is weighed (after moisture and temperature 
conditioning) before and after sample collection to determine the net 
gain due to collected PM2.5. The total volume of air sampled 
is determined by the sampler from the measured flow rate at actual 
ambient temperature and pressure and the sampling time. The mass 
concentration of PM2.5 in the ambient air is computed as the 
total mass of collected particles in the PM2.5 size range 
divided by the actual volume of air sampled, and is expressed in 
micrograms per cubic meter of air (g/m3).
    3.0 PM2.5 Measurement Range.
    3.1 Lower concentration limit. The lower detection limit of the mass 
concentration measurement range is estimated to be approximately 2 
g/m3, based on noted mass changes in field blanks in 
conjunction with the 24 m3 nominal total air sample volume 
specified for the 24-hour sample.
    3.2 Upper concentration limit. The upper limit of the mass 
concentration range is determined by the filter mass loading beyond 
which the sampler can no longer maintain the operating flow rate within 
specified limits due to increased pressure drop across the loaded 
filter. This upper limit cannot be specified precisely because it is a 
complex function of the ambient particle size distribution and type, 
humidity, the individual filter used, the capacity of the sampler flow 
rate control system, and perhaps other factors. Nevertheless, all 
samplers are estimated to be capable of measuring 24-hour 
PM2.5 mass concentrations of at least 200 g/
m3 while maintaining the operating flow rate within the 
specified limits.
    3.3 Sample period. The required sample period for PM2.5 
concentration measurements by this method shall be 1,380 to 1500 minutes 
(23 to 25 hours). However, when a sample period is less than 1,380 
minutes, the measured concentration (as determined by the collected 
PM2.5 mass divided by the actual sampled air volume), 
multiplied by the actual number of minutes in the sample period and 
divided by 1,440, may be used as if it were a valid concentration 
measurement for the specific purpose of determining a violation of the 
NAAQS. This value assumes that the PM2.5 concentration is 
zero for the remaining portion of the sample period and therefore 
represents the minimum concentration that could have been measured for 
the full 24-hour sample period. Accordingly, if the value thus 
calculated is high enough to be an exceedance, such an exceedance would 
be a valid exceedance for the sample period. When reported to AIRS, this 
data value should receive a special code to identify it as not to be 
commingled with normal concentration measurements or used for other 
purposes.
    4.0 Accuracy.
    4.1 Because the size and volatility of the particles making up 
ambient particulate matter vary over a wide range and the mass 
concentration of particles varies with particle size, it is difficult to 
define the accuracy of PM2.5 measurements in an absolute 
sense. The accuracy of PM2.5 measurements is therefore 
defined in a relative sense, referenced to measurements provided by this 
reference method. Accordingly, accuracy shall be defined as the degree 
of agreement between a subject field PM2.5 sampler and a 
collocated PM2.5 reference method audit sampler operating 
simultaneously at the monitoring site location of the subject sampler 
and includes both random (precision) and systematic (bias) errors. The 
requirements for this field sampler audit procedure are set forth in 
part 58, appendix A of this chapter.
    4.2 Measurement system bias. Results of collocated measurements 
where the duplicate sampler is a reference method sampler are used to 
assess a portion of the measurement system bias according to the 
schedule and procedure specified in part 58, appendix A of this chapter.
    4.3 Audits with reference method samplers to determine system 
accuracy and bias. According to the schedule and procedure specified in 
part 58, appendix A of this chapter, a reference method sampler is 
required to be located at each of selected PM2.5 SLAMS sites 
as a duplicate sampler. The results from the primary sampler and the 
duplicate reference method sampler are used to calculate accuracy of the 
primary sampler on a quarterly basis, bias of the primary sampler on an 
annual basis, and bias of a single reporting organization on an annual 
basis. Reference 2 in section 13.0 of this appendix provides additional 
information and guidance on these reference method audits.
    4.4 Flow rate accuracy and bias. Part 58, appendix A of this chapter 
requires that the flow rate accuracy and bias of individual 
PM2.5 samplers used in SLAMS monitoring networks be assessed 
periodically via audits of each sampler's operational flow rate. In 
addition, part 58, appendix A of this chapter requires that flow rate 
bias for each reference and equivalent method operated by each reporting 
organization be assessed quarterly and annually. Reference 2 in section 
13.0 of this appendix provides additional information and guidance on 
flow rate accuracy audits and calculations for accuracy and bias.
    5.0 Precision. A data quality objective of 10 percent coefficient of 
variation or better has

[[Page 76]]

been established for the operational precision of PM2.5 
monitoring data.
    5.1 Tests to establish initial operational precision for each 
reference method sampler are specified as a part of the requirements for 
designation as a reference method under Sec. 53.58 of this chapter.
    5.2 Measurement System Precision. Collocated sampler results, where 
the duplicate sampler is not a reference method sampler but is a sampler 
of the same designated method as the primary sampler, are used to assess 
measurement system precision according to the schedule and procedure 
specified in part 58, appendix A of this chapter. Part 58, appendix A of 
this chapter requires that these collocated sampler measurements be used 
to calculate quarterly and annual precision estimates for each primary 
sampler and for each designated method employed by each reporting 
organization. Reference 2 in section 13.0 of this appendix provides 
additional information and guidance on this requirement.
    6.0 Filter for PM2.5 Sample Collection. Any filter 
manufacturer or vendor who sells or offers to sell filters specifically 
identified for use with this PM2.5 reference method shall 
certify that the required number of filters from each lot of filters 
offered for sale as such have been tested as specified in this section 
6.0 and meet all of the following design and performance specifications.
    6.1 Size. Circular, 46.2 mm diameter 0.25 mm.
    6.2 Medium. Polytetrafluoroethylene (PTFE Teflon), with integral 
support ring.
    6.3 Support ring. Polymethylpentene (PMP) or equivalent inert 
material, 0.38 0.04 mm thick, outer diameter 46.2 mm 
0.25 mm, and width of 3.68 mm ( 0.00, -0.51 mm).
    6.4 Pore size. 2 m as measured by ASTM F 316-94.
    6.5 Filter thickness. 30 to 50 m.
    6.6 Maximum pressure drop (clean filter). 30 cm H2O 
column @ 16.67 L/min clean air flow.
    6.7 Maximum moisture pickup. Not more than 10 g weight 
increase after 24-hour exposure to air of 40 percent relative humidity, 
relative to weight after 24-hour exposure to air of 35 percent relative 
humidity.
    6.8 Collection efficiency. Greater than 99.7 percent, as measured by 
the DOP test (ASTM D 2986-91) with 0.3 m particles at the 
sampler's operating face velocity.
    6.9 Filter weight stability. Filter weight loss shall be less than 
20 g, as measured in each of the following two tests specified 
in sections 6.9.1 and 6.9.2 of this appendix. The following conditions 
apply to both of these tests: Filter weight loss shall be the average 
difference between the initial and the final filter weights of a random 
sample of test filters selected from each lot prior to sale. The number 
of filters tested shall be not less than 0.1 percent of the filters of 
each manufacturing lot, or 10 filters, whichever is greater. The filters 
shall be weighed under laboratory conditions and shall have had no air 
sample passed through them, i.e., filter blanks. Each test procedure 
must include initial conditioning and weighing, the test, and final 
conditioning and weighing. Conditioning and weighing shall be in 
accordance with sections 8.0 through 8.2 of this appendix and general 
guidance provided in reference 2 of section 13.0 of this appendix.
    6.9.1 Test for loose, surface particle contamination. After the 
initial weighing, install each test filter, in turn, in a filter 
cassette (Figures L-27, L-28, and L-29 of this appendix) and drop the 
cassette from a height of 25 cm to a flat hard surface, such as a 
particle-free wood bench. Repeat two times, for a total of three drop 
tests for each test filter. Remove the test filter from the cassette and 
weigh the filter. The average change in weight must be less than 20 
g.
    6.9.2 Test for temperature stability. After weighing each filter, 
place the test filters in a drying oven set at 40  deg.C 2 
deg.C for not less than 48 hours. Remove, condition, and reweigh each 
test filter. The average change in weight must be less than 20 
g.
    6.10 Alkalinity. Less than 25 microequivalents/gram of filter, as 
measured by the guidance given in reference 2 in section 13.0 of this 
appendix.
    6.11 Supplemental requirements. Although not required for 
determination of PM2.5 mass concentration under this 
reference method, additional specifications for the filter must be 
developed by users who intend to subject PM2.5 filter samples 
to subsequent chemical analysis. These supplemental specifications 
include background chemical contamination of the filter and any other 
filter parameters that may be required by the method of chemical 
analysis. All such supplemental filter specifications must be compatible 
with and secondary to the primary filter specifications given in this 
section 6.0 of this appendix.
    7.0 PM2.5 Sampler.
    7.1 Configuration. The sampler shall consist of a sample air inlet, 
downtube, particle size separator (impactor), filter holder assembly, 
air pump and flow rate control system, flow rate measurement device, 
ambient and filter temperature monitoring system, barometric pressure 
measurement system, timer, outdoor environmental enclosure, and suitable 
mechanical, electrical, or electronic control capability to meet or 
exceed the design and functional performance as specified in this 
section 7.0 of this appendix. The performance specifications require 
that the sampler:
    (a) Provide automatic control of sample volumetric flow rate and 
other operational parameters.
    (b) Monitor these operational parameters as well as ambient 
temperature and pressure.
    (c) Provide this information to the sampler operator at the end of 
each sample period in

[[Page 77]]

digital form, as specified in table L-1 of section 7.4.19 of this 
appendix.
    7.2 Nature of specifications. The PM2.5 sampler is 
specified by a combination of design and performance requirements. The 
sample inlet, downtube, particle size discriminator, filter cassette, 
and the internal configuration of the filter holder assembly are 
specified explicitly by design figures and associated mechanical 
dimensions, tolerances, materials, surface finishes, assembly 
instructions, and other necessary specifications. All other aspects of 
the sampler are specified by required operational function and 
performance, and the design of these other aspects (including the design 
of the lower portion of the filter holder assembly) is optional, subject 
to acceptable operational performance. Test procedures to demonstrate 
compliance with both the design and performance requirements are set 
forth in subpart E of part 53 of this chapter.
    7.3 Design specifications. Except as indicated in this section 7.3 
of this appendix, these components must be manufactured or reproduced 
exactly as specified, in an ISO 9001-registered facility, with 
registration initially approved and subsequently maintained during the 
period of manufacture. See Sec. 53.1(t) of this chapter for the 
definition of an ISO-registered facility. Minor modifications or 
variances to one or more components that clearly would not affect the 
aerodynamic performance of the inlet, downtube, impactor, or filter 
cassette will be considered for specific approval. Any such proposed 
modifications shall be described and submitted to the EPA for specific 
individual acceptability either as part of a reference or equivalent 
method application under part 53 of this chapter or in writing in 
advance of such an intended application under part 53 of this chapter.
    7.3.1 Sample inlet assembly. The sample inlet assembly, consisting 
of the inlet, downtube, and impactor shall be configured and assembled 
as indicated in Figure L-1 of this appendix and shall meet all 
associated requirements. A portion of this assembly shall also be 
subject to the maximum overall sampler leak rate specification under 
section 7.4.6 of this appendix.
    7.3.2 Inlet. The sample inlet shall be fabricated as indicated in 
Figures L-2 through L-18 of this appendix and shall meet all associated 
requirements.
    7.3.3 Downtube. The downtube shall be fabricated as indicated in 
Figure L-19 of this appendix and shall meet all associated requirements.
    7.3.4 Impactor.
    7.3.4.1 The impactor (particle size separator) shall be fabricated 
as indicated in Figures L-20 through L-24 of this appendix and shall 
meet all associated requirements. Following the manufacture and 
finishing of each upper impactor housing (Figure L-21 of this appendix), 
the dimension of the impaction jet must be verified by the manufacturer 
using Class ZZ go/no-go plug gauges that are traceable to NIST.
    7.3.4.2 Impactor filter specifications:
    (a) Size. Circular, 35 to 37 mm diameter.
    (b) Medium. Borosilicate glass fiber, without binder.
    (c) Pore size. 1 to 1.5 micrometer, as measured by ASTM F 316-80.
    (d) Thickness. 300 to 500 micrometers.
    7.3.4.3 Impactor oil specifications:
    (a) Composition. Tetramethyltetraphenyltrisiloxane, single-compound 
diffusion oil.
    (b) Vapor pressure. Maximum 2 x 10-8 mm Hg at 25  deg.C.
    (c) Viscosity. 36 to 40 centistokes at 25  deg.C.
    (d) Density. 1.06 to 1.07 g/cm3 at 25  deg.C.
    (e) Quantity. 1 mL 0.1 mL.
    7.3.5 Filter holder assembly. The sampler shall have a sample filter 
holder assembly to adapt and seal to the down tube and to hold and seal 
the specified filter, under section 6.0 of this appendix, in the sample 
air stream in a horizontal position below the downtube such that the 
sample air passes downward through the filter at a uniform face 
velocity. The upper portion of this assembly shall be fabricated as 
indicated in Figures L-25 and L-26 of this appendix and shall accept and 
seal with the filter cassette, which shall be fabricated as indicated in 
Figures L-27 through L-29 of this appendix.
    (a) The lower portion of the filter holder assembly shall be of a 
design and construction that:
    (1) Mates with the upper portion of the assembly to complete the 
filter holder assembly,
    (2) Completes both the external air seal and the internal filter 
cassette seal such that all seals are reliable over repeated filter 
changings, and
    (3) Facilitates repeated changing of the filter cassette by the 
sampler operator.
    (b) Leak-test performance requirements for the filter holder 
assembly are included in section 7.4.6 of this appendix.
    (c) If additional or multiple filters are stored in the sampler as 
part of an automatic sequential sample capability, all such filters, 
unless they are currently and directly installed in a sampling channel 
or sampling configuration (either active or inactive), shall be covered 
or (preferably) sealed in such a way as to:
    (1) Preclude significant exposure of the filter to possible 
contamination or accumulation of dust, insects, or other material that 
may be present in the ambient air, sampler, or sampler ventilation air 
during storage periods either before or after sampling; and
    (2) To minimize loss of volatile or semi-volatile PM sample 
components during storage of the filter following the sample period.
    7.3.6 Flow rate measurement adapter. A flow rate measurement adapter 
as specified in

[[Page 78]]

Figure L-30 of this appendix shall be furnished with each sampler.
    7.3.7 Surface finish. All internal surfaces exposed to sample air 
prior to the filter shall be treated electrolytically in a sulfuric acid 
bath to produce a clear, uniform anodized surface finish of not less 
than 1000 mg/ft2 (1.08 mg/cm2) in accordance with 
military standard specification (mil. spec.) 8625F, Type II, Class 1 in 
reference 4 of section 13.0 of this appendix. This anodic surface 
coating shall not be dyed or pigmented. Following anodization, the 
surfaces shall be sealed by immersion in boiling deionized water for not 
less than 15 minutes. Section 53.51(d)(2) of this chapter should also be 
consulted.
    7.3.8 Sampling height. The sampler shall be equipped with legs, a 
stand, or other means to maintain the sampler in a stable, upright 
position and such that the center of the sample air entrance to the 
inlet, during sample collection, is maintained in a horizontal plane and 
is 2.0 0.2 meters above the floor or other horizontal 
supporting surface. Suitable bolt holes, brackets, tie-downs, or other 
means should be provided to facilitate mechanically securing the sample 
to the supporting surface to prevent toppling of the sampler due to 
wind.
    7.4 Performance specifications.
    7.4.1 Sample flow rate. Proper operation of the impactor requires 
that specific air velocities be maintained through the device. 
Therefore, the design sample air flow rate through the inlet shall be 
16.67 L/min (1.000 m3/hour) measured as actual volumetric 
flow rate at the temperature and pressure of the sample air entering the 
inlet.
    7.4.2 Sample air flow rate control system. The sampler shall have a 
sample air flow rate control system which shall be capable of providing 
a sample air volumetric flow rate within the specified range, under 
section 7.4.1 of this appendix, for the specified filter, under section 
6.0 of this appendix, at any atmospheric conditions specified, under 
section 7.4.7 of this appendix, at a filter pressure drop equal to that 
of a clean filter plus up to 75 cm water column (55 mm Hg), and over the 
specified range of supply line voltage, under section 7.4.15.1 of this 
appendix. This flow control system shall allow for operator adjustment 
of the operational flow rate of the sampler over a range of at least 
15 percent of the flow rate specified in section 7.4.1 of 
this appendix.
    7.4.3 Sample flow rate regulation. The sample flow rate shall be 
regulated such that for the specified filter, under section 6.0 of this 
appendix, at any atmospheric conditions specified, under section 7.4.7 
of this appendix, at a filter pressure drop equal to that of a clean 
filter plus up to 75 cm water column (55 mm Hg), and over the specified 
range of supply line voltage, under section 7.4.15.1 of this appendix, 
the flow rate is regulated as follows:
    7.4.3.1 The volumetric flow rate, measured or averaged over 
intervals of not more than 5 minutes over a 24-hour period, shall not 
vary more than 5 percent from the specified 16.67 L/min flow 
rate over the entire sample period.
    7.4.3.2 The coefficient of variation (sample standard deviation 
divided by the mean) of the flow rate, measured over a 24-hour period, 
shall not be greater than 2 percent.
    7.4.3.3 The amplitude of short-term flow rate pulsations, such as 
may originate from some types of vacuum pumps, shall be attenuated such 
that they do not cause significant flow measurement error or affect the 
collection of particles on the particle collection filter.
    7.4.4 Flow rate cut off. The sampler's sample air flow rate control 
system shall terminate sample collection and stop all sample flow for 
the remainder of the sample period in the event that the sample flow 
rate deviates by more than 10 percent from the sampler design flow rate 
specified in section 7.4.1 of this appendix for more than 60 seconds. 
However, this sampler cut-off provision shall not apply during periods 
when the sampler is inoperative due to a temporary power interruption, 
and the elapsed time of the inoperative period shall not be included in 
the total sample time measured and reported by the sampler, under 
section 7.4.13 of this appendix.
    7.4.5 Flow rate measurement.
    7.4.5.1 The sampler shall provide a means to measure and indicate 
the instantaneous sample air flow rate, which shall be measured as 
volumetric flow rate at the temperature and pressure of the sample air 
entering the inlet, with an accuracy of 2 percent. The 
measured flow rate shall be available for display to the sampler 
operator at any time in either sampling or standby modes, and the 
measurement shall be updated at least every 30 seconds. The sampler 
shall also provide a simple means by which the sampler operator can 
manually start the sample flow temporarily during non-sampling modes of 
operation, for the purpose of checking the sample flow rate or the flow 
rate measurement system.
    7.4.5.2 During each sample period, the sampler's flow rate 
measurement system shall automatically monitor the sample volumetric 
flow rate, obtaining flow rate measurements at intervals of not greater 
than 30 seconds.
    (a) Using these interval flow rate measurements, the sampler shall 
determine or calculate the following flow-related parameters, scaled in 
the specified engineering units:
    (1) The instantaneous or interval-average flow rate, in L/min.
    (2) The value of the average sample flow rate for the sample period, 
in L/min.
    (3) The value of the coefficient of variation (sample standard 
deviation divided by the

[[Page 79]]

average) of the sample flow rate for the sample period, in percent.
    (4) The occurrence of any time interval during the sample period in 
which the measured sample flow rate exceeds a range of 5 
percent of the average flow rate for the sample period for more than 5 
minutes, in which case a warning flag indicator shall be set.
    (5) The value of the integrated total sample volume for the sample 
period, in m3.
    (b) Determination or calculation of these values shall properly 
exclude periods when the sampler is inoperative due to temporary 
interruption of electrical power, under section 7.4.13 of this appendix, 
or flow rate cut off, under section 7.4.4 of this appendix.
    (c) These parameters shall be accessible to the sampler operator as 
specified in table L-1 of section 7.4.19 of this appendix. In addition, 
it is strongly encouraged that the flow rate for each 5-minute interval 
during the sample period be available to the operator following the end 
of the sample period.
    7.4.6 Leak test capability.
    7.4.6.1 External leakage. The sampler shall include an external air 
leak-test capability consisting of components, accessory hardware, 
operator interface controls, a written procedure in the associated 
Operation/Instruction Manual, under section 7.4.18 of this appendix, and 
all other necessary functional capability to permit and facilitate the 
sampler operator to conveniently carry out a leak test of the sampler at 
a field monitoring site without additional equipment. The sampler 
components to be subjected to this leak test include all components and 
their interconnections in which external air leakage would or could 
cause an error in the sampler's measurement of the total volume of 
sample air that passes through the sample filter.
    (a) The suggested technique for the operator to use for this leak 
test is as follows:
    (1) Remove the sampler inlet and installs the flow rate measurement 
adapter supplied with the sampler, under section 7.3.6 of this appendix.
    (2) Close the valve on the flow rate measurement adapter and use the 
sampler air pump to draw a partial vacuum in the sampler, including (at 
least) the impactor, filter holder assembly (filter in place), flow 
measurement device, and interconnections between these devices, of at 
least 55 mm Hg (75 cm water column), measured at a location downstream 
of the filter holder assembly.
    (3) Plug the flow system downstream of these components to isolate 
the components under vacuum from the pump, such as with a built-in 
valve.
    (4) Stop the pump.
    (5) Measure the trapped vacuum in the sampler with a built-in 
pressure measuring device.
    (6) (i) Measure the vacuum in the sampler with the built-in pressure 
measuring device again at a later time at least 10 minutes after the 
first pressure measurement.
    (ii) Caution: Following completion of the test, the adaptor valve 
should be opened slowly to limit the flow rate of air into the sampler. 
Excessive air flow rate may blow oil out of the impactor.
    (7) Upon completion of the test, open the adaptor valve, remove the 
adaptor and plugs, and restore the sampler to the normal operating 
configuration.
    (b) The associated leak test procedure shall require that for 
successful passage of this test, the difference between the two pressure 
measurements shall not be greater than the number of mm of Hg specified 
for the sampler by the manufacturer, based on the actual internal volume 
of the sampler, that indicates a leak of less than 80 mL/min.
    (c) Variations of the suggested technique or an alternative external 
leak test technique may be required for samplers whose design or 
configuration would make the suggested technique impossible or 
impractical. The specific proposed external leak test procedure, or 
particularly an alternative leak test technique, proposed for a 
particular candidate sampler may be described and submitted to the EPA 
for specific individual acceptability either as part of a reference or 
equivalent method application under part 53 of this chapter or in 
writing in advance of such an intended application under part 53 of this 
chapter.
    7.4.6.2 Internal, filter bypass leakage. The sampler shall include 
an internal, filter bypass leak-check capability consisting of 
components, accessory hardware, operator interface controls, a written 
procedure in the Operation/Instruction Manual, and all other necessary 
functional capability to permit and facilitate the sampler operator to 
conveniently carry out a test for internal filter bypass leakage in the 
sampler at a field monitoring site without additional equipment. The 
purpose of the test is to determine that any portion of the sample flow 
rate that leaks past the sample filter without passing through the 
filter is insignificant relative to the design flow rate for the 
sampler.
    (a) The suggested technique for the operator to use for this leak 
test is as follows:
    (1) Carry out an external leak test as provided under section 
7.4.6.1 of this appendix which indicates successful passage of the 
prescribed external leak test.
    (2) Install a flow-impervious membrane material in the filter 
cassette, either with or without a filter, as appropriate, which 
effectively prevents air flow through the filter.
    (3) Use the sampler air pump to draw a partial vacuum in the 
sampler, downstream of the filter holder assembly, of at least 55 mm Hg 
(75 cm water column).
    (4) Plug the flow system downstream of the filter holder to isolate 
the components under

[[Page 80]]

vacuum from the pump, such as with a built-in valve.
    (5) Stop the pump.
    (6) Measure the trapped vacuum in the sampler with a built-in 
pressure measuring device.
    (7) Measure the vacuum in the sampler with the built-in pressure 
measuring device again at a later time at least 10 minutes after the 
first pressure measurement.
    (8) Remove the flow plug and membrane and restore the sampler to the 
normal operating configuration.
    (b) The associated leak test procedure shall require that for 
successful passage of this test, the difference between the two pressure 
measurements shall not be greater than the number of mm of Hg specified 
for the sampler by the manufacturer, based on the actual internal volume 
of the portion of the sampler under vacuum, that indicates a leak of 
less than 80 mL/min.
    (c) Variations of the suggested technique or an alternative 
internal, filter bypass leak test technique may be required for samplers 
whose design or configuration would make the suggested technique 
impossible or impractical. The specific proposed internal leak test 
procedure, or particularly an alternative internal leak test technique 
proposed for a particular candidate sampler may be described and 
submitted to the EPA for specific individual acceptability either as 
part of a reference or equivalent method application under part 53 of 
this chapter or in writing in advance of such intended application under 
part 53 of this chapter.
    7.4.7 Range of operational conditions. The sampler is required to 
operate properly and meet all requirements specified in this appendix 
over the following operational ranges.
    7.4.7.1 Ambient temperature. -30 to =45  deg.C (Note: Although for 
practical reasons, the temperature range over which samplers are 
required to be tested under part 53 of this chapter is -20 to =40 
deg.C, the sampler shall be designed to operate properly over this wider 
temperature range.).
    7.4.7.2 Ambient relative humidity. 0 to 100 percent.
    7.4.7.3 Barometric pressure range. 600 to 800 mm Hg.
    7.4.8 Ambient temperature sensor. The sampler shall have capability 
to measure the temperature of the ambient air surrounding the sampler 
over the range of -30 to =45  deg.C, with a resolution of 0.1  deg.C and 
accuracy of 2.0  deg.C, referenced as described in reference 
3 in section 13.0 of this appendix, with and without maximum solar 
insolation.
    7.4.8.1 The ambient temperature sensor shall be mounted external to 
the sampler enclosure and shall have a passive, naturally ventilated sun 
shield. The sensor shall be located such that the entire sun shield is 
at least 5 cm above the horizontal plane of the sampler case or 
enclosure (disregarding the inlet and downtube) and external to the 
vertical plane of the nearest side or protuberance of the sampler case 
or enclosure. The maximum temperature measurement error of the ambient 
temperature measurement system shall be less than 1.6  deg.C at 1 m/s 
wind speed and 1000 W/m2 solar radiation intensity.
    7.4.8.2 The ambient temperature sensor shall be of such a design and 
mounted in such a way as to facilitate its convenient dismounting and 
immersion in a liquid for calibration and comparison to the filter 
temperature sensor, under section 7.4.11 of this appendix.
    7.4.8.3 This ambient temperature measurement shall be updated at 
least every 30 seconds during both sampling and standby (non-sampling) 
modes of operation. A visual indication of the current (most recent) 
value of the ambient temperature measurement, updated at least every 30 
seconds, shall be available to the sampler operator during both sampling 
and standby (non-sampling) modes of operation, as specified in table L-1 
of section 7.4.19 of this appendix.
    7.4.8.4 This ambient temperature measurement shall be used for the 
purpose of monitoring filter temperature deviation from ambient 
temperature, as required by section 7.4.11 of this appendix, and may be 
used for purposes of effecting filter temperature control, under section 
7.4.10 of this appendix, or computation of volumetric flow rate, under 
sections 7.4.1 to 7.4.5 of this appendix, if appropriate.
    7.4.8.5 Following the end of each sample period, the sampler shall 
report the maximum, minimum, and average temperature for the sample 
period, as specified in table L-1 of section 7.4.19 of this appendix.
    7.4.9 Ambient barometric sensor. The sampler shall have capability 
to measure the barometric pressure of the air surrounding the sampler 
over a range of 600 to 800 mm Hg referenced as described in reference 3 
in section 13.0 of this appendix; also see part 53, subpart E of this 
chapter. This barometric pressure measurement shall have a resolution of 
5 mm Hg and an accuracy of 10 mm Hg and shall be updated at 
least every 30 seconds. A visual indication of the value of the current 
(most recent) barometric pressure measurement, updated at least every 30 
seconds, shall be available to the sampler operator during both sampling 
and standby (non-sampling) modes of operation, as specified in table L-1 
of section 7.4.19 of this appendix. This barometric pressure measurement 
may be used for purposes of computation of volumetric flow rate, under 
sections 7.4.1 to 7.4.5 of this appendix, if appropriate. Following the 
end of a sample period, the sampler shall report the maximum, minimum, 
and mean barometric pressures for the sample period, as specified in 
table L-1 of section 7.4.19 of this appendix.

[[Page 81]]

    7.4.10 Filter temperature control (sampling and post-sampling). The 
sampler shall provide a means to limit the temperature rise of the 
sample filter (all sample filters for sequential samplers), from 
insolation and other sources, to no more 5  deg.C above the temperature 
of the ambient air surrounding the sampler, during both sampling and 
post-sampling periods of operation. The post-sampling period is the non-
sampling period between the end of the active sampling period and the 
time of retrieval of the sample filter by the sampler operator.
    7.4.11 Filter temperature sensor(s).
    7.4.11.1 The sampler shall have the capability to monitor the 
temperature of the sample filter (all sample filters for sequential 
samplers) over the range of -30 to =45  deg.C during both sampling and 
non-sampling periods. While the exact location of this temperature 
sensor is not explicitly specified, the filter temperature measurement 
system must demonstrate agreement, within 1  deg.C, with a test 
temperature sensor located within 1 cm of the center of the filter 
downstream of the filter during both sampling and non-sampling modes, as 
specified in the filter temperature measurement test described in part 
53, subpart E of this chapter. This filter temperature measurement shall 
have a resolution of 0.1  deg.C and accuracy of 1.0  deg.C, 
referenced as described in reference 3 in section 13.0 of this appendix. 
This temperature sensor shall be of such a design and mounted in such a 
way as to facilitate its reasonably convenient dismounting and immersion 
in a liquid for calibration and comparison to the ambient temperature 
sensor under section 7.4.8 of this appendix.
    7.4.11.2 The filter temperature measurement shall be updated at 
least every 30 seconds during both sampling and standby (non-sampling) 
modes of operation. A visual indication of the current (most recent) 
value of the filter temperature measurement, updated at least every 30 
seconds, shall be available to the sampler operator during both sampling 
and standby (non-sampling) modes of operation, as specified in table L-1 
of section 7.4.19 of this appendix.
    7.4.11.3 For sequential samplers, the temperature of each filter 
shall be measured individually unless it can be shown, as specified in 
the filter temperature measurement test described in Sec. 53.57 of this 
chapter, that the temperature of each filter can be represented by fewer 
temperature sensors.
    7.4.11.4 The sampler shall also provide a warning flag indicator 
following any occurrence in which the filter temperature (any filter 
temperature for sequential samplers) exceeds the ambient temperature by 
more than 5  deg.C for more than 30 consecutive minutes during either 
the sampling or post-sampling periods of operation, as specified in 
table L-1 of section 7.4.19 of this appendix, under section 10.12 of 
this appendix, regarding sample validity when a warning flag occurs. It 
is further recommended (not required) that the sampler be capable of 
recording the maximum differential between the measured filter 
temperature and the ambient temperature and its time and date of 
occurrence during both sampling and post-sampling (non-sampling) modes 
of operation and providing for those data to be accessible to the 
sampler operator following the end of the sample period, as suggested in 
table L-1 of section 7.4.19 of this appendix.
    7.4.12 Clock/timer system.
    (a) The sampler shall have a programmable real-time clock timing/
control system that:
    (1) Is capable of maintaining local time and date, including year, 
month, day-of-month, hour, minute, and second to an accuracy of 
1.0 minute per month.
    (2) Provides a visual indication of the current system time, 
including year, month, day-of-month, hour, and minute, updated at least 
each minute, for operator verification.
    (3) Provides appropriate operator controls for setting the correct 
local time and date.
    (4) Is capable of starting the sample collection period and sample 
air flow at a specific, operator-settable time and date, and stopping 
the sample air flow and terminating the sampler collection period 24 
hours (1440 minutes) later, or at a specific, operator-settable time and 
date.
    (b) These start and stop times shall be readily settable by the 
sampler operator to within 1.0 minute. The system shall 
provide a visual indication of the current start and stop time settings, 
readable to 1.0 minute, for verification by the operator, 
and the start and stop times shall also be available via the data output 
port, as specified in table L-1 of section 7.4.19 of this appendix. Upon 
execution of a programmed sample period start, the sampler shall 
automatically reset all sample period information and warning flag 
indications pertaining to a previous sample period. Refer also to 
section 7.4.15.4 of this appendix regarding retention of current date 
and time and programmed start and stop times during a temporary 
electrical power interruption.
    7.4.13 Sample time determination. The sampler shall be capable of 
determining the elapsed sample collection time for each PM2.5 
sample, accurate to within 1.0 minute, measured as the time 
between the start of the sampling period, under section 7.4.12 of this 
appendix and the termination of the sample period, under section 7.4.12 
of this appendix or section 7.4.4 of this appendix. This elapsed sample 
time shall not include periods when the sampler is inoperative due to a 
temporary interruption of electrical power, under section 7.4.15.4 of 
this appendix. In the event that the elapsed sample time determined for 
the sample period is not within the

[[Page 82]]

range specified for the required sample period in section 3.3 of this 
appendix, the sampler shall set a warning flag indicator. The date and 
time of the start of the sample period, the value of the elapsed sample 
time for the sample period, and the flag indicator status shall be 
available to the sampler operator following the end of the sample 
period, as specified in table L-1 of section 7.4.19 of this appendix.
    7.4.14 Outdoor environmental enclosure. The sampler shall have an 
outdoor enclosure (or enclosures) suitable to protect the filter and 
other non-weatherproof components of the sampler from precipitation, 
wind, dust, extremes of temperature and humidity; to help maintain 
temperature control of the filter (or filters, for sequential samplers); 
and to provide reasonable security for sampler components and settings.
    7.4.15 Electrical power supply.
    7.4.15.1 The sampler shall be operable and function as specified 
herein when operated on an electrical power supply voltage of 105 to 125 
volts AC (RMS) at a frequency of 59 to 61 Hz. Optional operation as 
specified at additional power supply voltages and/or frequencies shall 
not be precluded by this requirement.
    7.4.15.2 The design and construction of the sampler shall comply 
with all applicable National Electrical Code and Underwriters 
Laboratories electrical safety requirements.
    7.4.15.3 The design of all electrical and electronic controls shall 
be such as to provide reasonable resistance to interference or 
malfunction from ordinary or typical levels of stray electromagnetic 
fields (EMF) as may be found at various monitoring sites and from 
typical levels of electrical transients or electronic noise as may often 
or occasionally be present on various electrical power lines.
    7.4.15.4 In the event of temporary loss of electrical supply power 
to the sampler, the sampler shall not be required to sample or provide 
other specified functions during such loss of power, except that the 
internal clock/timer system shall maintain its local time and date 
setting within 1 minute per week, and the sampler shall 
retain all other time and programmable settings and all data required to 
be available to the sampler operator following each sample period for at 
least 7 days without electrical supply power. When electrical power is 
absent at the operator-set time for starting a sample period or is 
interrupted during a sample period, the sampler shall automatically 
start or resume sampling when electrical power is restored, if such 
restoration of power occurs before the operator-set stop time for the 
sample period.
    7.4.15.5 The sampler shall have the capability to record and retain 
a record of the year, month, day-of-month, hour, and minute of the start 
of each power interruption of more than 1 minute duration, up to 10 such 
power interruptions per sample period. (More than 10 such power 
interruptions shall invalidate the sample, except where an exceedance is 
measured, under section 3.3 of this appendix.) The sampler shall provide 
for these power interruption data to be available to the sampler 
operator following the end of the sample period, as specified in table 
L-1 of section 7.4.19 of this appendix.
    7.4.16 Control devices and operator interface. The sampler shall 
have mechanical, electrical, or electronic controls, control devices, 
electrical or electronic circuits as necessary to provide the timing, 
flow rate measurement and control, temperature control, data storage and 
computation, operator interface, and other functions specified. 
Operator-accessible controls, data displays, and interface devices shall 
be designed to be simple, straightforward, reliable, and easy to learn, 
read, and operate under field conditions. The sampler shall have 
provision for operator input and storage of up to 64 characters of 
numeric (or alphanumeric) data for purposes of site, sampler, and sample 
identification. This information shall be available to the sampler 
operator for verification and change and for output via the data output 
port along with other data following the end of a sample period, as 
specified in table L-1 of section 7.4.19 of this appendix. All data 
required to be available to the operator following a sample collection 
period or obtained during standby mode in a post-sampling period shall 
be retained by the sampler until reset, either manually by the operator 
or automatically by the sampler upon initiation of a new sample 
collection period.
    7.4.17 Data output port requirement. The sampler shall have a 
standard RS-232C data output connection through which digital data may 
be exported to an external data storage or transmission device. All 
information which is required to be available at the end of each sample 
period shall be accessible through this data output connection. The 
information that shall be accessible though this output port is 
summarized in table L-1 of section 7.4.19 of this appendix. Since no 
specific format for the output data is provided, the sampler 
manufacturer or vendor shall make available to sampler purchasers 
appropriate computer software capable of receiving exported sampler data 
and correctly translating the data into a standard spreadsheet format 
and optionally any other formats as may be useful to sampler users. This 
requirement shall not preclude the sampler from offering other types of 
output connections in addition to the required RS-232C port.
    7.4.18 Operation/instruction manual. The sampler shall include an 
associated comprehensive operation or instruction manual, as required by 
part 53 of this chapter, which includes detailed operating instructions 
on

[[Page 83]]

the setup, operation, calibration, and maintenance of the sampler. This 
manual shall provide complete and detailed descriptions of the 
operational and calibration procedures prescribed for field use of the 
sampler and all instruments utilized as part of this reference method. 
The manual shall include adequate warning of potential safety hazards 
that may result from normal use or malfunction of the method and a 
description of necessary safety precautions. The manual shall also 
include a clear description of all procedures pertaining to 
installation, operation, periodic and corrective maintenance, and 
troubleshooting, and shall include parts identification diagrams.
    7.4.19 Data reporting requirements. The various information that the 
sampler is required to provide and how it is to be provided is 
summarized in the following table L-1.

                                             Table L-1--Summary of Information To Be Provided By the Sampler
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                             Availability                                        Format
                                    Appendix L section -------------------------------------------------------------------------------------------------
    Information to be provided          reference                        End of        Visual
                                                          Anytime1       period2      display3    Data output4    Digital reading5          Units
--------------------------------------------------------------------------------------------------------------------------------------------------------
Flow rate, 30-second maximum       7.4.5.1............         ............                   *   XX.X...............  L/min
 interval.
Flow rate, average for the sample  7.4.5.2............            *                    *          XX.X...............  L/min
 period.
Flow rate, CV, for sample period.  7.4.5.2............            *                    *     XX.X...............  %
Flow rate, 5-min. average out of   7.4.5.2............                         On/Off.............  ...................
 spec. (FLAG6).
Sample volume, total.............  7.4.5.2............            *                   XX.X...............  m3
Temperature, ambient, 30-second    7.4.8..............         ............         ............  XX.X...............    deg.C
 interval.
Temperature, ambient, min., max.,  7.4.8..............            *                   XX.X...............    deg.C
 average for the sample period.
Baro pressure, ambient, 30-second  7.4.9..............         ............         ............  XXX................  mm Hg
 interval.
Baro pressure, ambient, min.,      7.4.9..............            *                   XXX................  mm Hg
 max., average for the sample
 period.
Filter temperature, 30-second      7.4.11.............         ............         ............  XX.X...............    deg.C
 interval.
Filter temperature differential,   7.4.11.............            *                   On/Off.............  ...................
 30-second interval, out of spec.
 (FLAG6).
Filter temperature, maximum        7.4.11.............            *             *             *             *   X.X, YY/MM/DD HH:mm    deg.C, Yr./Mon./
 differential from ambient, date,                                                                                                     Day Hrs. min
 time of occurrence.
Date and time....................  7.4.12.............         ............         ............  YY/MM/DD HH:mm.....  Yr./Mon./Day Hrs.
                                                                                                                                      min
Sample start and stop time         7.4.12.............                              YY/MM/DD HH:mm.....  Yr./Mon./Day Hrs.
 settings.                                                                                                                            min
Sample period start time.........  7.4.12.............  ............                  YYYY/MM/DD HH:mm...  Yr./Mon./Day Hrs.
                                                                                                                                      min
Elapsed sample time..............  7.4.13.............            *                   HH:mm..............  Hrs. min
Elapsed sample time, out of spec.  7.4.13.............  ............                  On/Off.............  ...................
 (FLAG6).

[[Page 84]]

 
Power interruptions 1 min., start  7.4.15.5...........            *                    *          1HH:mm, 2HH:mm, etc  Hrs. min
 time of first 10.                                                                                               ....
User-entered information, such as  7.4.16.............                         As entered.........  ...................
 sampler and site identification.
--------------------------------------------------------------------------------------------------------------------------------------------------------
 Provision of this information is required.
*Provision of this information is optional. If information related to the entire sample period is optionally provided prior to the end of the sample
  period, the value provided should be the value calculated for the portion of the sampler period completed up to the time the information is provided.
 Indicates that this information is also required to be provided to the AIRS data bank; see Sec.  Sec.  58.26 and 58.35 of this chapter.
 
1 Information is required to be available to the operator at any time the sampler is operating, whether sampling or not.
2 Information relates to the entire sampler period and must be provided following the end of the sample period until reset manually by the operator or
  automatically by the sampler upon the start of a new sample period.
3 Information shall be available to the operator visually.
4 Information is to be available as digital data at the sampler's data output port specified in section 7.4.16 of this appendix following the end of the
  sample period until reset manually by the operator or automatically by the sampler upon the start of a new sample period.
5 Digital readings, both visual and data output, shall have not less than the number of significant digits and resolution specified.
6 Flag warnings may be displayed to the operator by a single-flag indicator or each flag may be displayed individually. Only a set (on) flag warning
  must be indicated; an off (unset) flag may be indicated by the absence of a flag warning. Sampler users should refer to section 10.12 of this appendix
  regarding the validity of samples for which the sampler provided an associated flag warning.

    8.0 Filter Weighing. See reference 2 in section 13.0 of this 
appendix, for additional, more detailed guidance.
    8.1 Analytical balance. The analytical balance used to weigh filters 
must be suitable for weighing the type and size of filters specified, 
under section 6.0 of this appendix, and have a readability of 
1 g. The balance shall be calibrated as specified 
by the manufacturer at installation and recalibrated immediately prior 
to each weighing session. See reference 2 in section 13.0 of this 
appendix for additional guidance.
    8.2 Filter conditioning. All sample filters used shall be 
conditioned immediately before both the pre- and post-sampling weighings 
as specified below. See reference 2 in section 13.0 of this appendix for 
additional guidance.
    8.2.1 Mean temperature. 20 - 23  deg.C.
    8.2.2 Temperature control. 2  deg.C over 24 hours.
    8.2.3 Mean humidity. Generally, 30-40 percent relative humidity; 
however, where it can be shown that the mean ambient relative humidity 
during sampling is less than 30 percent, conditioning is permissible at 
a mean relative humidity within 5 relative humidity percent 
of the mean ambient relative humidity during sampling, but not less than 
20 percent.
    8.2.4 Humidity control. 5 relative humidity percent over 
24 hours.
    8.2.5 Conditioning time. Not less than 24 hours.
    8.3 Weighing procedure.
    8.3.1 New filters should be placed in the conditioning environment 
immediately upon arrival and stored there until the pre-sampling 
weighing. See reference 2 in section 13.0 of this appendix for 
additional guidance.
    8.3.2 The analytical balance shall be located in the same controlled 
environment in which the filters are conditioned. The filters shall be 
weighed immediately following the conditioning period without 
intermediate or transient exposure to other conditions or environments.
    8.3.3 Filters must be conditioned at the same conditions (humidity 
within 5 relative humidity percent) before both the pre- and 
post-sampling weighings.
    8.3.4 Both the pre- and post-sampling weighings should be carried 
out on the same analytical balance, using an effective technique to 
neutralize static charges on the filter, under reference 2 in section 
13.0 of this appendix. If possible, both weighings should be carried out 
by the same analyst.
    8.3.5 The pre-sampling (tare) weighing shall be within 30 days of 
the sampling period.
    8.3.6 The post-sampling conditioning and weighing shall be completed 
within 240 hours (10 days) after the end of the sample period, unless 
the filter sample is maintained at 4  deg.C or less during the entire 
time between retrieval from the sampler and the start of the 
conditioning, in which case the period shall not exceed 30 days. 
Reference 2 in section 13.0 of this appendix has additional guidance on 
transport of cooled filters.

[[Page 85]]

    8.3.7 Filter blanks.
    8.3.7.1 New field blank filters shall be weighed along with the pre-
sampling (tare) weighing of each lot of PM2.5 filters. These 
blank filters shall be transported to the sampling site, installed in 
the sampler, retrieved from the sampler without sampling, and reweighed 
as a quality control check.
    8.3.7.2 New laboratory blank filters shall be weighed along with the 
pre-sampling (tare) weighing of each set of PM2.5 filters. 
These laboratory blank filters should remain in the laboratory in 
protective containers during the field sampling and should be reweighed 
as a quality control check.
    8.3.8 Additional guidance for proper filter weighing and related 
quality assurance activities is provided in reference 2 in section 13.0 
of this appendix.
    9.0 Calibration. Reference 2 in section 13.0 of this appendix 
contains additional guidance.
    9.1 General requirements.
    9.1.1 Multipoint calibration and single-point verification of the 
sampler's flow rate measurement device must be performed periodically to 
establish and maintain traceability of subsequent flow measurements to a 
flow rate standard.
    9.1.2 An authoritative flow rate standard shall be used for 
calibrating or verifying the sampler's flow rate measurement device with 
an accuracy of 2 percent. The flow rate standard shall be a 
separate, stand-alone device designed to connect to the flow rate 
measurement adapter, Figure L-30 of this appendix. This flow rate 
standard must have its own certification and be traceable to a National 
Institute of Standards and Technology (NIST) primary standard for volume 
or flow rate. If adjustments to the sampler's flow rate measurement 
system calibration are to be made in conjunction with an audit of the 
sampler's flow measurement system, such adjustments shall be made 
following the audit. Reference 2 in section 13.0 of this appendix 
contains additional guidance.
    9.1.3 The sampler's flow rate measurement device shall be re-
calibrated after electromechanical maintenance or transport of the 
sampler.
    9.2 Flow rate calibration/verification procedure.
    9.2.1 PM2.5 samplers may employ various types of flow 
control and flow measurement devices. The specific procedure used for 
calibration or verification of the flow rate measurement device will 
vary depending on the type of flow rate controller and flow rate 
measurement employed. Calibration shall be in terms of actual ambient 
volumetric flow rates (Qa), measured at the sampler's inlet 
downtube. The generic procedure given here serves to illustrate the 
general steps involved in the calibration of a PM2.5 sampler. 
The sampler operation/instruction manual required under section 7.4.18 
of this appendix and the Quality Assurance Handbook in reference 2 in 
section 13.0 of this appendix provide more specific and detailed 
guidance for calibration.
    9.2.2 The flow rate standard used for flow rate calibration shall 
have its own certification and be traceable to a NIST primary standard 
for volume or flow rate. A calibration relationship for the flow rate 
standard, e.g., an equation, curve, or family of curves relating actual 
flow rate (Qa) to the flow rate indicator reading, shall be 
established that is accurate to within 2 percent over the expected range 
of ambient temperatures and pressures at which the flow rate standard 
may be used. The flow rate standard must be re-calibrated or re-verified 
at least annually.
    9.2.3 The sampler flow rate measurement device shall be calibrated 
or verified by removing the sampler inlet and connecting the flow rate 
standard to the sampler's downtube in accordance with the operation/
instruction manual, such that the flow rate standard accurately measures 
the sampler's flow rate. The sampler operator shall first carry out a 
sampler leak check and confirm that the sampler passes the leak test and 
then verify that no leaks exist between the flow rate standard and the 
sampler.
    9.2.4 The calibration relationship between the flow rate (in actual 
L/min) indicated by the flow rate standard and by the sampler's flow 
rate measurement device shall be established or verified in accordance 
with the sampler operation/instruction manual. Temperature and pressure 
corrections to the flow rate indicated by the flow rate standard may be 
required for certain types of flow rate standards. Calibration of the 
sampler's flow rate measurement device shall consist of at least three 
separate flow rate measurements (multipoint calibration) evenly spaced 
within the range of -10 percent to =10 percent of the sampler's 
operational flow rate, section 7.4.1 of this appendix. Verification of 
the sampler's flow rate shall consist of one flow rate measurement at 
the sampler's operational flow rate. The sampler operation/instruction 
manual and reference 2 in section 13.0 of this appendix provide 
additional guidance.
    9.2.5 If during a flow rate verification the reading of the 
sampler's flow rate indicator or measurement device differs by 
 4 percent or more from the flow rate measured by the flow 
rate standard, a new multipoint calibration shall be performed and the 
flow rate verification must then be repeated.
    9.2.6 Following the calibration or verification, the flow rate 
standard shall be removed from the sampler and the sampler inlet shall 
be reinstalled. Then the sampler's normal operating flow rate (in L/min) 
shall be determined with a clean filter in place. If the flow rate 
indicated by the sampler differs by 2 percent or more from 
the required sampler flow rate, the sampler flow rate must be

[[Page 86]]

adjusted to the required flow rate, under section 7.4.1 of this 
appendix.
    9.3 Periodic calibration or verification of the calibration of the 
sampler's ambient temperature, filter temperature, and barometric 
pressure measurement systems is also required. Reference 3 of section 
13.0 of this appendix contains additional guidance.
    10.0 PM2.5 Measurement Procedure. The detailed procedure 
for obtaining valid PM2.5 measurements with each specific 
sampler designated as part of a reference method for PM2.5 
under part 53 of this chapter shall be provided in the sampler-specific 
operation or instruction manual required by section 7.4.18 of this 
appendix. Supplemental guidance is provided in section 2.12 of the 
Quality Assurance Handbook listed in reference 2 in section 13.0 of this 
appendix. The generic procedure given here serves to illustrate the 
general steps involved in the PM2.5 sample collection and 
measurement, using a PM2.5 reference method sampler.
    10.1 The sampler shall be set up, calibrated, and operated in 
accordance with the specific, detailed guidance provided in the specific 
sampler's operation or instruction manual and in accordance with a 
specific quality assurance program developed and established by the 
user, based on applicable supplementary guidance provided in reference 2 
in section 13.0 of this appendix.
    10.2 Each new sample filter shall be inspected for correct type and 
size and for pinholes, particles, and other imperfections. Unacceptable 
filters should be discarded. A unique identification number shall be 
assigned to each filter, and an information record shall be established 
for each filter. If the filter identification number is not or cannot be 
marked directly on the filter, alternative means, such as a number-
identified storage container, must be established to maintain positive 
filter identification.
    10.3 Each filter shall be conditioned in the conditioning 
environment in accordance with the requirements specified in section 8.2 
of this appendix.
    10.4 Following conditioning, each filter shall be weighed in 
accordance with the requirements specified in section 8.0 of this 
appendix and the presampling weight recorded with the filter 
identification number.
    10.5 A numbered and preweighed filter shall be installed in the 
sampler following the instructions provided in the sampler operation or 
instruction manual.
    10.6 The sampler shall be checked and prepared for sample collection 
in accordance with instructions provided in the sampler operation or 
instruction manual and with the specific quality assurance program 
established for the sampler by the user.
    10.7 The sampler's timer shall be set to start the sample collection 
at the beginning of the desired sample period and stop the sample 
collection 24 hours later.
    10.8 Information related to the sample collection (site location or 
identification number, sample date, filter identification number, and 
sampler model and serial number) shall be recorded and, if appropriate, 
entered into the sampler.
    10.9 The sampler shall be allowed to collect the PM2.5 
sample during the set 24-hour time period.
    10.10 Within 96 hours of the end of the sample collection period, 
the filter, while still contained in the filter cassette, shall be 
carefully removed from the sampler, following the procedure provided in 
the sampler operation or instruction manual and the quality assurance 
program, and placed in a protective container. The protective container 
shall contain no loose material that could be transferred to the filter. 
The protective container shall hold the filter cassette securely such 
that the cover shall not come in contact with the filter's surfaces. 
Reference 2 in section 13.0 of this appendix contains additional 
information.
    10.11 The total sample volume in actual m3 for the 
sampling period and the elapsed sample time shall be obtained from the 
sampler and recorded in accordance with the instructions provided in the 
sampler operation or instruction manual. All sampler warning flag 
indications and other information required by the local quality 
assurance program shall also be recorded.
    10.12 All factors related to the validity or representativeness of 
the sample, such as sampler tampering or malfunctions, unusual 
meteorological conditions, construction activity, fires or dust storms, 
etc. shall be recorded as required by the local quality assurance 
program. The occurrence of a flag warning during a sample period shall 
not necessarily indicate an invalid sample but rather shall indicate the 
need for specific review of the QC data by a quality assurance officer 
to determine sample validity.
    10.13 After retrieval from the sampler, the exposed filter 
containing the PM2.5 sample should be transported to the 
filter conditioning environment as soon as possible ideally to arrive at 
the conditioning environment within 24 hours for conditioning and 
subsequent weighing. During the period between filter retrieval from the 
sampler and the start of the conditioning, the filter shall be 
maintained as cool as practical and continuously protected from exposure 
to temperatures over 25  deg.C. See section 8.3.6 of this appendix 
regarding time limits for completing the post-sampling weighing. See 
reference 2 in section 13.0 of this appendix for additional guidance on 
transporting filter samplers to the conditioning and weighing 
laboratory.
    10.14. The exposed filter containing the PM2.5 sample 
shall be re-conditioned in the conditioning environment in accordance

[[Page 87]]

with the requirements specified in section 8.2 of this appendix.
    10.15. The filter shall be reweighed immediately after conditioning 
in accordance with the requirements specified in section 8.0 of this 
appendix, and the postsampling weight shall be recorded with the filter 
identification number.
    10.16 The PM2.5 concentration shall be calculated as 
specified in section 12.0 of this appendix.
    11.0 Sampler Maintenance. The sampler shall be maintained as 
described by the sampler's manufacturer in the sampler-specific 
operation or instruction manual required under section 7.4.18 of this 
appendix and in accordance with the specific quality assurance program 
developed and established by the user based on applicable supplementary 
guidance provided in reference 2 in section 13.0 of this appendix.
    12.0 Calculations
    12.1 (a) The PM2.5 concentration is calculated as:

PM2.5 = (Wf - Wi)/Va

where:

PM2.5 = mass concentration of PM2.5, g/
m3;
Wf, Wi = final and initial weights, respectively, 
of the filter used to collect the PM2.5 particle sample, 
g;
Va = total air volume sampled in actual volume units, as 
provided by the sampler, m3.

    Note: Total sample time must be between 1,380 and 1,500 minutes (23 
and 25 hrs) for a fully valid PM2.5 sample; however, see also 
section 3.3 of this appendix.
    13.0 References.
    1. Quality Assurance Handbook for Air Pollution Measurement Systems, 
Volume I, Principles. EPA/600/R-94/038a, April 1994. Available from 
CERI, ORD Publications, U.S. Environmental Protection Agency, 26 West 
Martin Luther King Drive, Cincinnati, Ohio 45268.
    2. Copies of section 2.12 of the Quality Assurance Handbook for Air 
Pollution Measurement Systems, Volume II, Ambient Air Specific Methods, 
EPA/600/R-94/038b, are available from Department E (MD-77B), U.S. EPA, 
Research Triangle Park, NC 27711.
    3. Quality Assurance Handbook for Air Pollution Measurement Systems, 
Volume IV: Meteorological Measurements, (Revised Edition) EPA/600/R-94/
038d, March, 1995. Available from CERI, ORD Publications, U.S. 
Environmental Protection Agency, 26 West Martin Luther King Drive, 
Cincinnati, Ohio 45268.
    4. Military standard specification (mil. spec.) 8625F, Type II, 
Class 1 as listed in Department of Defense Index of Specifications and 
Standards (DODISS), available from DODSSP-Customer Service, 
Standardization Documents Order Desk, 700 Robbins Avenue, Building 4D, 
Philadelphia, PA 1911-5094.
    14.0 Figures L-1 through L-30 to Appendix L.

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[62 FR 38714, July 18, 1997, as amended at 64 FR 19719, Apr. 22, 1999]

    Appendix M to Part 50--Reference Method for the Determination of 
         Particulate Matter as PM10 in the Atmosphere

    1.0 Applicability.
    1.1 This method provides for the measurement of the mass 
concentration of particulate matter with an aerodynamic diameter less 
than or equal to a nominal 10 micrometers (PM1O) in ambient 
air over a 24-hour period for purposes of determining attainment and 
maintenance of the primary and secondary national ambient air quality 
standards for particulate matter specified in Sec. 50.6 of this chapter. 
The measurement process is nondestructive, and the PM10 
sample can be subjected to subsequent physical or chemical analyses. 
Quality assurance procedures and guidance are provided in part 58, 
Appendices A and B of this chapter and in references 1 and 2 of section 
12.0 of this appendix.
    2.0 Principle.
    2.1 An air sampler draws ambient air at a constant flow rate into a 
specially shaped inlet where the suspended particulate matter is 
inertially separated into one or more size fractions within the 
PM10 size range. Each size fraction in the 
PM1O size range is then collected on a separate filter over 
the specified sampling period. The particle size discrimination 
characteristics (sampling effectiveness and 50 percent cutpoint) of the 
sampler inlet are prescribed as performance specifications in part 53 of 
this chapter.
    2.2 Each filter is weighed (after moisture equilibration) before and 
after use to determine the net weight (mass) gain due to collected 
PM10. The total volume of air sampled, measured at the actual 
ambient temperature and pressure, is determined from the measured flow 
rate and the sampling time. The mass concentration of PM10 in 
the ambient air is computed as the total mass of collected particles in 
the PM10 size range divided by the volume of air sampled, and 
is expressed in micrograms per actual cubic meter (g/
m3).
    2.3 A method based on this principle will be considered a reference 
method only if the associated sampler meets the requirements specified 
in this appendix and the requirements in part 53 of this chapter, and 
the method has been designated as a reference method in accordance with 
part 53 of this chapter.
    3.0 Range.
    3.1 The lower limit of the mass concentration range is determined by 
the repeatability of filter tare weights, assuming the nominal air 
sample volume for the sampler. For samplers having an automatic filter-
changing mechanism, there may be no upper limit. For samplers that do 
not have an automatic filter-changing mechanism, the upper limit is 
determined by the filter mass loading beyond which the sampler no longer 
maintains the operating flow rate within specified limits due to 
increased pressure drop across the loaded filter. This upper limit 
cannot be specified precisely because it is a complex function of the 
ambient particle size distribution and type, humidity, filter type, and 
perhaps other factors. Nevertheless, all samplers should be capable of 
measuring 24-hour PM10 mass concentrations of at least 300 
g/m\3\ while maintaining the operating flow rate within the 
specified limits.
    4.0 Precision.
    4.1 The precision of PM10 samplers must be 5 g/
m\3\ for PM10 concentrations below 80 g/m\3\ and 7 
percent for PM10 concentrations above 80 g/m\3\, as 
required by part 53 of this chapter, which prescribes a test procedure 
that determines the variation in the PM10 concentration 
measurements of identical samplers under typical sampling conditions. 
Continual assessment of precision via collocated samplers is required by 
part 58 of this chapter for PM10 samplers used in certain 
monitoring networks.
    5.0 Accuracy.
    5.1 Because the size of the particles making up ambient particulate 
matter varies over a wide range and the concentration of particles 
varies with particle size, it is difficult to define the absolute 
accuracy of PM10 samplers. Part 53 of this chapter provides a 
specification for the sampling effectiveness of PM10 
samplers. This specification requires that the expected mass 
concentration calculated for a candidate PM10 sampler, when 
sampling a specified particle size distribution, be within 
10 percent of that calculated for an ideal sampler whose 
sampling effectiveness is explicitly specified. Also, the particle size 
for 50 percent sampling effectiveness is required to be 
100.5 micrometers. Other specifications related to accuracy 
apply to flow measurement and calibration, filter media, analytical 
(weighing) procedures, and artifact. The flow rate accuracy of 
PM10 samplers used in certain monitoring networks is required 
by part 58 of this chapter to be assessed periodically via flow rate 
audits.
    6.0 Potential Sources of Error.
    6.1 Volatile Particles. Volatile particles collected on filters are 
often lost during shipment and/or storage of the filters prior to the 
post-sampling weighing \3\. Although shipment or storage of loaded 
filters is sometimes unavoidable, filters should be reweighed as soon as 
practical to minimize these losses.
    6.2 Artifacts. Positive errors in PM10 concentration 
measurements may result from retention of gaseous species on filters 
4, 5. Such errors include the retention of sulfur dioxide and 
nitric acid. Retention of sulfur

[[Page 119]]

dioxide on filters, followed by oxidation to sulfate, is referred to as 
artifact sulfate formation, a phenomenon which increases with increasing 
filter alkalinity \6\. Little or no artifact sulfate formation should 
occur using filters that meet the alkalinity specification in section 
7.2.4 of this appendix, Artifact nitrate formation, resulting primarily 
from retention of nitric acid, occurs to varying degrees on many filter 
types, including glass fiber, cellulose ester, and many quartz fiber 
filters 5, 7, 8, 9, 10. Loss of true atmospheric particulate 
nitrate during or following sampling may also occur due to dissociation 
or chemical reaction. This phenomenon has been observed on 
Teflonfilters \8\ and inferred for quartz fiber filters 
11, 12. The magnitude of nitrate artifact errors in 
PM10 mass concentration measurements will vary with location 
and ambient temperature; however, for most sampling locations, these 
errors are expected to be small.
    6.3 Humidity. The effects of ambient humidity on the sample are 
unavoidable. The filter equilibration procedure in section 9.0 of this 
appendix is designed to minimize the effects of moisture on the filter 
medium.
    6.4 Filter Handling. Careful handling of filters between presampling 
and postsampling weighings is necessary to avoid errors due to damaged 
filters or loss of collected particles from the filters. Use of a filter 
cartridge or cassette may reduce the magnitude of these errors. Filters 
must also meet the integrity specification in section 7.2.3 of this 
appendix.
    6.5 Flow Rate Variation. Variations in the sampler's operating flow 
rate may alter the particle size discrimination characteristics of the 
sampler inlet. The magnitude of this error will depend on the 
sensitivity of the inlet to variations in flow rate and on the particle 
distribution in the atmosphere during the sampling period. The use of a 
flow control device, under section 7.1.3 of this appendix, is required 
to minimize this error.
    6.6 Air Volume Determination. Errors in the air volume determination 
may result from errors in the flow rate and/or sampling time 
measurements. The flow control device serves to minimize errors in the 
flow rate determination, and an elapsed time meter, under section 7.1.5 
of this appendix, is required to minimize the error in the sampling time 
measurement.
    7.0 Apparatus.
    7.1 PM10 Sampler.
    7.1.1 The sampler shall be designed to:
    (a) Draw the air sample into the sampler inlet and through the 
particle collection filter at a uniform face velocity.
    (b) Hold and seal the filter in a horizontal position so that sample 
air is drawn downward through the filter.
    (c) Allow the filter to be installed and removed conveniently.
    (d) Protect the filter and sampler from precipitation and prevent 
insects and other debris from being sampled.
    (e) Minimize air leaks that would cause error in the measurement of 
the air volume passing through the filter.
    (f) Discharge exhaust air at a sufficient distance from the sampler 
inlet to minimize the sampling of exhaust air.
    (g) Minimize the collection of dust from the supporting surface.
    7.1.2 The sampler shall have a sample air inlet system that, when 
operated within a specified flow rate range, provides particle size 
discrimination characteristics meeting all of the applicable performance 
specifications prescribed in part 53 of this chapter. The sampler inlet 
shall show no significant wind direction dependence. The latter 
requirement can generally be satisfied by an inlet shape that is 
circularly symmetrical about a vertical axis.
    7.1.3 The sampler shall have a flow control device capable of 
maintaining the sampler's operating flow rate within the flow rate 
limits specified for the sampler inlet over normal variations in line 
voltage and filter pressure drop.
    7.1.4 The sampler shall provide a means to measure the total flow 
rate during the sampling period. A continuous flow recorder is 
recommended but not required. The flow measurement device shall be 
accurate to 2 percent.
    7.1.5 A timing/control device capable of starting and stopping the 
sampler shall be used to obtain a sample collection period of 24 
1 hr (1,440 60 min). An elapsed time meter, 
accurate to within 15 minutes, shall be used to measure 
sampling time. This meter is optional for samplers with continuous flow 
recorders if the sampling time measurement obtained by means of the 
recorder meets the 15 minute accuracy specification.
    7.1.6 The sampler shall have an associated operation or instruction 
manual as required by part 53 of this chapter which includes detailed 
instructions on the calibration, operation, and maintenance of the 
sampler.
    7.2 Filters.
    7.2.1 Filter Medium. No commercially available filter medium is 
ideal in all respects for all samplers. The user's goals in sampling 
determine the relative importance of various filter characteristics, 
e.g., cost, ease of handling, physical and chemical characteristics, 
etc., and, consequently, determine the choice among acceptable filters. 
Furthermore, certain types of filters may not be suitable for use with 
some samplers, particularly under heavy loading conditions (high mass 
concentrations), because of high or rapid increase in the filter flow 
resistance that would exceed the capability of the sampler's flow 
control device. However, samplers equipped with automatic filter-
changing

[[Page 120]]

mechanisms may allow use of these types of filters. The specifications 
given below are minimum requirements to ensure acceptability of the 
filter medium for measurement of PM10 mass concentrations. 
Other filter evaluation criteria should be considered to meet individual 
sampling and analysis objectives.
    7.2.2 Collection Efficiency. 99 percent, as measured by 
the DOP test (ASTM-2986) with 0.3 m particles at the sampler's 
operating face velocity.
    7.2.3 Integrity. 5 g/m\3\ (assuming sampler's 
nominal 24-hour air sample volume). Integrity is measured as the 
PM10 concentration equivalent corresponding to the average 
difference between the initial and the final weights of a random sample 
of test filters that are weighed and handled under actual or simulated 
sampling conditions, but have no air sample passed through them, i.e., 
filter blanks. As a minimum, the test procedure must include initial 
equilibration and weighing, installation on an inoperative sampler, 
removal from the sampler, and final equilibration and weighing.
    7.2.4 Alkalinity. 25 microequivalents/gram of filter, as measured by 
the procedure given in reference 13 of section 12.0 of this appendix 
following at least two months storage in a clean environment (free from 
contamination by acidic gases) at room temperature and humidity.
    7.3 Flow Rate Transfer Standard. The flow rate transfer standard 
must be suitable for the sampler's operating flow rate and must be 
calibrated against a primary flow or volume standard that is traceable 
to the National Institute of Standard and Technology (NIST). The flow 
rate transfer standard must be capable of measuring the sampler's 
operating flow rate with an accuracy of 2 percent.
    7.4 Filter Conditioning Environment.
    7.4.1 Temperature range. 15 to 30 C.
    7.4.2 Temperature control. 3 C.
    7.4.3 Humidity range. 20% to 45% RH.
    7.4.4 Humidity control. 5% RH.
    7.5 Analytical Balance. The analytical balance must be suitable for 
weighing the type and size of filters required by the sampler. The range 
and sensitivity required will depend on the filter tare weights and mass 
loadings. Typically, an analytical balance with a sensitivity of 0.1 mg 
is required for high volume samplers (flow rates >0.5 m\3\/min). Lower 
volume samplers (flow rates 0.5 m\3\/min) will require a more sensitive 
balance.
    8.0 Calibration.
    8.1 General Requirements.
    8.1.1 Calibration of the sampler's flow measurement device is 
required to establish traceability of subsequent flow measurements to a 
primary standard. A flow rate transfer standard calibrated against a 
primary flow or volume standard shall be used to calibrate or verify the 
accuracy of the sampler's flow measurement device.
    8.1.2 Particle size discrimination by inertial separation requires 
that specific air velocities be maintained in the sampler's air inlet 
system. Therefore, the flow rate through the sampler's inlet must be 
maintained throughout the sampling period within the design flow rate 
range specified by the manufacturer. Design flow rates are specified as 
actual volumetric flow rates, measured at existing conditions of 
temperature and pressure (Qa).
    8.2 Flow Rate Calibration Procedure.
    8.2.1 PM10 samplers employ various types of flow control 
and flow measurement devices. The specific procedure used for flow rate 
calibration or verification will vary depending on the type of flow 
controller and flow rate indicator employed. Calibration is in terms of 
actual volumetric flow rates (Qa) to meet the requirements of 
section 8.1 of this appendix. The general procedure given here serves to 
illustrate the steps involved in the calibration. Consult the sampler 
manufacturer's instruction manual and reference 2 of section 12.0 of 
this appendix for specific guidance on calibration. Reference 14 of 
section 12.0 of this appendix provides additional information on various 
other measures of flow rate and their interrelationships.
    8.2.2 Calibrate the flow rate transfer standard against a primary 
flow or volume standard traceable to NIST. Establish a calibration 
relationship, e.g., an equation or family of curves, such that 
traceability to the primary standard is accurate to within 2 percent 
over the expected range of ambient conditions, i.e., temperatures and 
pressures, under which the transfer standard will be used. Recalibrate 
the transfer standard periodically.
    8.2.3 Following the sampler manufacturer's instruction manual, 
remove the sampler inlet and connect the flow rate transfer standard to 
the sampler such that the transfer standard accurately measures the 
sampler's flow rate. Make sure there are no leaks between the transfer 
standard and the sampler.
    8.2.4 Choose a minimum of three flow rates (actual m\3\/min), spaced 
over the acceptable flow rate range specified for the inlet, under 
section 7.1.2 of the appendix, that can be obtained by suitable 
adjustment of the sampler flow rate. In accordance with the sampler 
manufacturer's instruction manual, obtain or verify the calibration 
relationship between the flow rate (actual m\3\/min) as indicated by the 
transfer standard and the sampler's flow indicator response. Record the 
ambient temperature and barometric pressure. Temperature and pressure 
corrections to subsequent flow indicator readings may be required for 
certain types of flow measurement devices. When such corrections are 
necessary, correction on an individual or

[[Page 121]]

daily basis is preferable. However, seasonal average temperature and 
average barometric pressure for the sampling site may be incorporated 
into the sampler calibration to avoid daily corrections. Consult the 
sampler manufacturer's instruction manual and reference 2 in section 
12.0 of this appendix for additional guidance.
    8.2.5 Following calibration, verify that the sampler is operating at 
its design flow rate (actual m\3\/min) with a clean filter in place.
    8.2.6 Replace the sampler inlet.
    9.0 Procedure.
    9.1 The sampler shall be operated in accordance with the specific 
guidance provided in the sampler manufacturer's instruction manual and 
in reference 2 in section 12.0 of this appendix. The general procedure 
given here assumes that the sampler's flow rate calibration is based on 
flow rates at ambient conditions (Qa) and serves to 
illustrate the steps involved in the operation of a PM10 
sampler.
    9.2 Inspect each filter for pinholes, particles, and other 
imperfections. Establish a filter information record and assign an 
identification number to each filter.
    9.3 Equilibrate each filter in the conditioning environment (see 
7.4) for at least 24 hours.
    9.4 Following equilibration, weigh each filter and record the 
presampling weight with the filter identification number.
    9.5 Install a preweighed filter in the sampler following the 
instructions provided in the sampler manufacturer's instruction manual.
    9.6 (a) Turn on the sampler and allow it to establish run-
temperature conditions. Record the flow indicator reading and, if 
needed, the ambient temperature and barometric pressure. Determine the 
sampler flow rate (actual m\3\/min) in accordance with the instructions 
provided in the sampler manufacturer's instruction manual.
    (b) Note: No onsite temperature or pressure measurements are 
necessary if the sampler's flow indicator does not require temperature 
or pressure corrections or if seasonal average temperature and average 
barometric pressure for the sampling site are incorporated into the 
sampler calibration, under section 8.2.4 of this appendix. If individual 
or daily temperature and pressure corrections are required, ambient 
temperature and barometric pressure can be obtained by on-site 
measurements or from a nearby weather station. Barometric pressure 
readings obtained from airports must be station pressure, not corrected 
to sea level, and may need to be corrected for differences in elevation 
between the sampling site and the airport.
    9.7 If the flow rate is outside the acceptable range specified by 
the manufacturer, check for leaks, and if necessary, adjust the flow 
rate to the specified setpoint. Stop the sampler.
    9.8 Set the timer to start and stop the sampler at appropriate 
times. Set the elapsed time meter to zero or record the initial meter 
reading.
    9.9 Record the sample information (site location or identification 
number, sample date, filter identification number, and sampler model and 
serial number).
    9.10 Sample for 241 hours.
    9.11 Determine and record the average flow rate (Qa) in 
actual m\3\/min for the sampling period in accordance with the 
instructions provided in the sampler manufacturer's instruction manual. 
Record the elapsed time meter final reading and, if needed, the average 
ambient temperature and barometric pressure for the sampling period, in 
note following section 9.6 of this appendix.
    9.12 Carefully remove the filter from the sampler, following the 
sampler manufacturer's instruction manual. Touch only the outer edges of 
the filter.
    9.13 Place the filter in a protective holder or container, e.g., 
petri dish, glassine envelope, or manila folder.
    9.14 Record any factors such as meteorological conditions, 
construction activity, fires or dust storms, etc., that might be 
pertinent to the measurement on the filter information record.
    9.15 Transport the exposed sample filter to the filter conditioning 
environment as soon as possible for equilibration and subsequent 
weighing.
    9.16 Equilibrate the exposed filter in the conditioning environment 
for at least 24 hours under the same temperature and humidity conditions 
used for presampling filter equilibration (see section 9.3 of this 
appendix).
    9.17 Immediately after equilibration, reweigh the filter and record 
the postsampling weight with the filter identification number.
    10.0 Sampler Maintenance.
    10.1 The PM10 sampler shall be maintained in strict 
accordance with the maintenance procedures specified in the sampler 
manufacturer's instruction manual.
    11.0 Calculations.
    11.1 Calculate the total volume of air sampled as:

V = Qat

where:

V = total air sampled, at ambient temperature and 
pressure,m3;
Qa = average sample flow rate at ambient temperature and 
pressure, m3/min; and
t = sampling time, min.
    11.2 (a) Calculate the PM10 concentration as:

PM10 = (Wf-Wi) x 10\6\/V

where:


[[Page 122]]


PM10 = mass concentration of PM10, g/
m\3\;
Wf, Wi = final and initial weights of filter 
collecting PM1O particles, g; and
10\6\ = conversion of g to g.

    (b) Note: If more than one size fraction in the PM10 size 
range is collected by the sampler, the sum of the net weight gain by 
each collection filter [(Wf-Wi)] is used 
to calculate the PM10 mass concentration.
    12.0 References.
    1. Quality Assurance Handbook for Air Pollution Measurement Systems, 
Volume I, Principles. EPA-600/9-76-005, March 1976. Available from CERI, 
ORD Publications, U.S. Environmental Protection Agency, 26 West St. 
Clair Street, Cincinnati, OH 45268.
    2. Quality Assurance Handbook for Air Pollution Measurement Systems, 
Volume II, Ambient Air Specific Methods. EPA-600/4-77-027a, May 1977. 
Available from CERI, ORD Publications, U.S. Environmental Protection 
Agency, 26 West St. Clair Street, Cincinnati, OH 45268.
    3. Clement, R.E., and F.W. Karasek. Sample Composition Changes in 
Sampling and Analysis of Organic Compounds in Aerosols. Int. J. Environ. 
Analyt. Chem., 7:109, 1979.
    4. Lee, R.E., Jr., and J. Wagman. A Sampling Anomaly in the 
Determination of Atmospheric Sulfate Concentration. Amer. Ind. Hyg. 
Assoc. J., 27:266, 1966.
    5. Appel, B.R., S.M. Wall, Y. Tokiwa, and M. Haik. Interference 
Effects in Sampling Particulate Nitrate in Ambient Air. Atmos. Environ., 
13:319, 1979.
    6. Coutant, R.W. Effect of Environmental Variables on Collection of 
Atmospheric Sulfate. Environ. Sci. Technol., 11:873, 1977.Spicer, C.W., 
and P. Schumacher. Interference in Sampling Atmospheric Particulate 
Nitrate. Atmos. Environ., 11:873, 1977.
    8. Appel, B.R., Y. Tokiwa, and M. Haik. Sampling of Nitrates in 
Ambient Air. Atmos. Environ., 15:283, 1981.
    9. Spicer, C.W., and P.M. Schumacher. Particulate Nitrate: 
Laboratory and Field Studies of Major Sampling Interferences. Atmos. 
Environ., 13:543, 1979.
    10. Appel, B.R. Letter to Larry Purdue, U.S. EPA, Environmental 
Monitoring and Support Laboratory. March 18, 1982, Docket No. A-82-37, 
II-I-1.
    11. Pierson, W.R., W.W. Brachaczek, T.J. Korniski, T.J. Truex, and 
J.W. Butler. Artifact Formation of Sulfate, Nitrate, and Hydrogen Ion on 
Backup Filters: Allegheny Mountain Experiment. J. Air Pollut. Control 
Assoc., 30:30, 1980.
    12. Dunwoody, C.L. Rapid Nitrate Loss From PM10 Filters. 
J. Air Pollut. Control Assoc., 36:817, 1986.
    13. Harrell, R.M. Measuring the Alkalinity of Hi-Vol Air Filters. 
EMSL/RTP-SOP-QAD-534, October 1985. Available from the U.S. 
Environmental Protection Agency, EMSL/QAD, Research Triangle Park, NC 
27711.
    14. Smith, F., P.S. Wohlschlegel, R.S.C. Rogers, and D.J. Mulligan. 
Investigation of Flow Rate Calibration Procedures Associated With the 
High Volume Method for Determination of Suspended Particulates. EPA-600/
4-78-047, U.S. Environmental Protection Agency, Research Triangle Park, 
NC 27711, 1978.

[62 FR 38753, July 18, 1997]

   Appendix N to Part 50--Interpretation of the National Ambient Air 
                Quality Standards for Particulate Matter

    1.0 General.
    (a) This appendix explains the data handling conventions and 
computations necessary for determining when the annual and 24-hour 
primary and secondary national ambient air quality standards for PM 
specified in Sec. 50.7 of this chapter are met. Particulate matter is 
measured in the ambient air as PM10 and PM2.5 
(particles with an aerodynamic diameter less than or equal to a nominal 
10 and 2.5 micrometers, respectively) by a reference method based on 
appendix M of this part for PM10 and on appendix L of this 
part for PM2.5, as applicable, and designated in accordance 
with part 53 of this chapter, or by an equivalent method designated in 
accordance with part 53 of this chapter. Data handling and computation 
procedures to be used in making comparisons between reported 
PM10 and PM2.5 concentrations and the levels of 
the PM standards are specified in the following sections.
    (b) Data resulting from uncontrollable or natural events, for 
example structural fires or high winds, may require special 
consideration. In some cases, it may be appropriate to exclude these 
data because they could result in inappropriate values to compare with 
the levels of the PM standards. In other cases, it may be more 
appropriate to retain the data for comparison with the level of the PM 
standards and then allow the EPA to formulate the appropriate regulatory 
response. Whether to exclude, retain, or make adjustments to the data 
affected by uncontrollable or natural events is subject to the approval 
of the appropriate Regional Administrator.
    (c) The terms used in this appendix are defined as follows:
    Average and mean refer to an arithmetic mean.
    Daily value for PM refers to the 24-hour average concentration of PM 
calculated or measured from midnight to midnight (local time) for 
PM10 or PM2.5.
    Designated monitors are those monitoring sites designated in a State 
PM Monitoring Network Description for spatial averaging in areas opting 
for spatial averaging in accordance with part 58 of this chapter.

[[Page 123]]

    98th percentile (used for PM2.5) means the 
daily value out of a year of monitoring data below which 98 percent of 
all values in the group fall.
    99th percentile (used for PM10) means the 
daily value out of a year of monitoring data below which 99 percent of 
all values in the group fall.
    Year refers to a calendar year.
    (d) Sections 2.1 and 2.5 of this appendix contain data handling 
instructions for the option of using a spatially averaged network of 
monitors for the annual standard. If spatial averaging is not considered 
for an area, then the spatial average is equivalent to the annual 
average of a single site and is treated accordingly in subsequent 
calculations. For example, paragraph (a)(3) of section 2.1 of this 
appendix could be eliminated since the spatial average would be 
equivalent to the annual average.
    2.0 Comparisons with the PM2.5 Standards.
    2.1 Annual PM2.5 Standard.
    (a) The annual PM2.5 standard is met when the 3-year 
average of the spatially averaged annual means is less than or equal to 
15.0 g/m3. The 3-year average of the spatially 
averaged annual means is determined by averaging quarterly means at each 
monitor to obtain the annual mean PM2.5 concentrations at 
each monitor, then averaging across all designated monitors, and finally 
averaging for 3 consecutive years. The steps can be summarized as 
follows:
    (1) Average 24-hour measurements to obtain quarterly means at each 
monitor.
    (2) Average quarterly means to obtain annual means at each monitor.
    (3) Average across designated monitoring sites to obtain an annual 
spatial mean for an area (this can be one site in which case the spatial 
mean is equal to the annual mean).
    (4) Average 3 years of annual spatial means to obtain a 3-year 
average of spatially averaged annual means.
    (b) In the case of spatial averaging, 3 years of spatial averages 
are required to demonstrate that the standard has been met. Designated 
sites with less than 3 years of data shall be included in spatial 
averages for those years that data completeness requirements are met. 
For the annual PM2.5 standard, a year meets data completeness 
requirements when at least 75 percent of the scheduled sampling days for 
each quarter have valid data. However, years with high concentrations 
and more than a minimal amount of data (at least 11 samples in each 
quarter) shall not be ignored just because they are comprised of 
quarters with less than complete data. Thus, in computing annual 
spatially averaged means, years containing quarters with at least 11 
samples but less than 75 percent data completeness shall be included in 
the computation if the resulting spatially averaged annual mean 
concentration (rounded according to the conventions of section 2.3 of 
this appendix) is greater than the level of the standard.
    (c) Situations may arise in which there are compelling reasons to 
retain years containing quarters which do not meet the data completeness 
requirement of 75 percent or the minimum number of 11 samples. The use 
of less than complete data is subject to the approval of the appropriate 
Regional Administrator.
    (d) The equations for calculating the 3-year average annual mean of 
the PM2.5 standard are given in section 2.5 of this appendix.
    2.2 24-Hour PM2.5 Standard.
    (a) The 24-hour PM2.5 standard is met when the 3-year 
average of the 98th percentile values at each monitoring site 
is less than or equal to 65 g/m3. This comparison 
shall be based on 3 consecutive, complete years of air quality data. A 
year meets data completeness requirements when at least 75 percent of 
the scheduled sampling days for each quarter have valid data. However, 
years with high concentrations shall not be ignored just because they 
are comprised of quarters with less than complete data. Thus, in 
computing the 3-year average 98th percentile value, years 
containing quarters with less than 75 percent data completeness shall be 
included in the computation if the annual 98th percentile 
value (rounded according to the conventions of section 2.3 of this 
appendix) is greater than the level of the standard.
    (b) Situations may arise in which there are compelling reasons to 
retain years containing quarters which do not meet the data completeness 
requirement. The use of less than complete data is subject to the 
approval of the appropriate Regional Administrator.
    (c) The equations for calculating the 3-year average of the annual 
98th percentile values is given in section 2.6 of this 
appendix.
    2.3 Rounding Conventions. For the purposes of comparing calculated 
values to the applicable level of the standard, it is necessary to round 
the final results of the calculations described in sections 2.5 and 2.6 
of this appendix. For the annual PM2.5 standard, the 3-year 
average of the spatially averaged annual means shall be rounded to the 
nearest 0.1 g/m3 (decimals 0.05 and greater are 
rounded up to the next 0.1, and any decimal lower than 0.05 is rounded 
down to the nearest 0.1). For the 24-hour PM2.5 standard, the 
3-year average of the annual 98th percentile values shall be 
rounded to the nearest 1 g/m3 (decimals 0.5 and 
greater are rounded up to nearest whole number, and any decimal lower 
than 0.5 is rounded down to the nearest whole number).
    2.4 Monitoring Considerations.
    (a) Section 58.13 of this chapter specifies the required minimum 
frequency of sampling

[[Page 124]]

for PM2.5. Exceptions to the specified sampling frequencies, 
such as a reduced frequency during a season of expected low 
concentrations, are subject to the approval of the appropriate Regional 
Administrator. Section 58.14 of 40 CFR part 58 and section 2.8 of 
appendix D of 40 CFR part 58, specify which monitors are eligible for 
making comparisons with the PM standards. In determining a spatial mean 
using two or more monitoring sites operating in a given year, the annual 
mean for an individual site may be included in the spatial mean if and 
only if the mean for that site meets the criterion specified in Sec. 2.8 
of appendix D of 40 CFR part 58. In the event data from an otherwise 
eligible site is excluded from being averaged with data from other sites 
on the basis of this criterion, then the 3-year mean from that site 
shall be compared directly to the annual standard.
    (b) For the annual PM2.5 standard, when designated 
monitors are located at the same site and are reporting PM2.5 
values for the same time periods, and when spatial averaging has been 
chosen, their concentrations shall be averaged before an area-wide 
spatial average is calculated. Such monitors will then be considered as 
one monitor.
    2.5 Equations for the Annual PM2.5 Standard.
    (a) An annual mean value for PM2.5 is determined by first 
averaging the daily values of a calendar quarter:

                               Equation 1
[GRAPHIC] [TIFF OMITTED] TR18JY97.000

where:

xq,y,s = the mean for quarter q of year y for site s;
nq = the number of monitored values in the quarter; and
xi,q,y,s = the ith value in quarter q for year y 
for site s.

    (b) The following equation is then to be used for calculation of the 
annual mean:

                               Equation 2
[GRAPHIC] [TIFF OMITTED] TR18JY97.001

where:

xy,s = the annual mean concentration for year y (y = 1, 2, or 
3) and for site s; and
xq,y,s = the mean for quarter q of year y for site s.

    (c)(1) The spatially averaged annual mean for year y is computed by 
first calculating the annual mean for each site designated to be 
included in a spatial average, xy,s, and then computing the 
average of these values across sites:

                               Equation 3
[GRAPHIC] [TIFF OMITTED] TR18JY97.002

where:

xy = the spatially averaged mean for year y;
xy,s = the annual mean for year y and site s; and
ns = the number of sites designated to be averaged.

    (2) In the event that an area designated for spatial averaging has 
two or more sites at the same location producing data for the same time 
periods, the sites are averaged together before using Equation 3 by:

                               Equation 4
[GRAPHIC] [TIFF OMITTED] TR18JY97.003

where:

xy,s* = the annual mean for year y for the sites at the same 
location (which will now be considered one site);
nc = the number of sites at the same location designated to 
be included in the spatial average; and
xy,s = the annual mean for year y and site s.

    (d) The 3-year average of the spatially averaged annual means is 
calculated by using the following equation:

                               Equation 5
[GRAPHIC] [TIFF OMITTED] TR18JY97.004

where:

x = the 3-year average of the spatially averaged annual means; and
xy = the spatially averaged annual mean for year y.

Example 1--Area Designated for Spatial Averaging That Meets the Primary 
                    Annual PM2.5 Standard.

    a. In an area designated for spatial averaging, four designated 
monitors recorded data in at least 1 year of a particular 3-year period. 
Using Equations 1 and 2, the annual means for PM2.5 at each 
site are calculated for each year. The following table can be created 
from the results. Data completeness percentages for the quarter with the 
fewest number of samples are also shown.

[[Page 125]]



                                                         Table 1--Results from Equations 1 and 2
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                       Site 1        Site 2        Site 3        Site 4
                                                                                                                                            Spatial mean
--------------------------------------------------------------------------------------------------------------------------------------------------------
Year 1.........................................  Annual mean (g/m\3\)....          12.7  ............  ............  ............         12.7
                                                 % data completeness..............          80             0             0             0    ............
Year 2.........................................  Annual mean (g/m\3\)....          12.6          17.5          15.2  ............         15.05
                                                 % data completeness..............          90            63            38             0    ............
Year 3.........................................  Annual mean (g/m\3\)....          12.5          18.5          14.1          16.9         15.50
                                                 % data completeness..............          90            80            85            50    ............
3-year mean....................................  .................................  ............  ............  ............  ............         14.42
--------------------------------------------------------------------------------------------------------------------------------------------------------

    b. The data from these sites are averaged in the order described in 
section 2.1 of this appendix. Note that the annual mean from site 3 in 
year 2 and the annual mean from site 4 in year 3 do not meet the 75 
percent data completeness criteria. Assuming the 38 percent data 
completeness represents a quarter with fewer than 11 samples, site 3 in 
year 2 does not meet the minimum data completeness requirement of 11 
samples in each quarter. The site is therefore excluded from the 
calculation of the spatial mean for year 2. However, since the spatial 
mean for year 3 is above the level of the standard and the minimum data 
requirement of 11 samples in each quarter has been met, the annual mean 
from site 4 in year 3 is included in the calculation of the spatial 
mean for year 3 and in the calculation of the 3-year average. The 3-year 
average is rounded to 14.4 g/m3, indicating that 
this area meets the annual PM2.5 standard.

 Example 2--Area With Two Monitors at the Same Location That Meets the 
                Primary Annual PM2.5 Standard.

    a. In an area designated for spatial averaging, six designated 
monitors, with two monitors at the same location (5 and 6), recorded 
data in a particular 3-year period. Using Equations 1 and 2, the annual 
means for PM2.5 are calculated for each year. The following 
table can be created from the results.

                                                         Table 2--Results From Equations 1 and 2
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                Average of 5
                                               Site 1        Site 2        Site 3        Site 4        Site 5        Site 6         and 6       Spatial
       Annual mean (g/m\3\)                                                                                                             mean
 
--------------------------------------------------------------------------------------------------------------------------------------------------------
Year 1....................................          12.9           9.9          12.6          11.1          14.5          14.6        14.55        12.21
Year 2....................................          14.5          13.3          12.2          10.9          16.1          16.0        16.05        13.39
Year 3....................................          14.4          12.4          11.5           9.7          12.3          12.1        12.20        12.04
3-Year mean...............................  ............  ............  ............  ............  ............  ............  ............       12.55
--------------------------------------------------------------------------------------------------------------------------------------------------------

    b. The annual means for sites 5 and 6 are averaged together using 
Equation 4 before the spatial average is calculated using Equation 3 
since they are in the same location. The 3-year mean is rounded to 12.6 
g/m3, indicating that this area meets the annual 
PM2.5 standard.

  Example 3--Area With a Single Monitor That Meets the Primary Annual 
                       PM2.5 Standard.

    a. Given data from a single monitor in an area, the calculations are 
as follows. Using Equations 1 and 2, the annual means for 
PM2.5 are calculated for each year. If the annual means are 
10.28, 17.38, and 12.25 g/m3, then the 3-year mean 
is:
[GRAPHIC] [TIFF OMITTED] TR18JY97.005

    b. This value is rounded to 13.3, indicating that this area meets 
the annual PM2.5 standard.
    2.6 Equations for the 24-Hour PM2.5 Standard.
    (a) When the data for a particular site and year meet the data 
completeness requirements in section 2.2 of this appendix, calculation 
of the 98th percentile is accomplished by the following 
steps. All the daily values from a particular site and year comprise a 
series of values (x1, x2, x3, ..., 
xn), that can be sorted into a series where each number is 
equal to or larger than the preceding number (x[1], 
x[2], x[3], ..., x[n]). In this case, 
x[1] is the smallest number and x[n] is the 
largest value. The 98th percentile is found from the

[[Page 126]]

sorted series of daily values which is ordered from the lowest to the 
highest number. Compute (0.98)  x  (n) as the number ``i.d'', where 
``i'' is the integer part of the result and ``d'' is the decimal part of 
the result. The 98th percentile value for year y, 
P0.98, y, is given by Equation 6:

                               Equation 6
[GRAPHIC] [TIFF OMITTED] TR18JY97.006

where:

P0.98,y = 98th percentile for year y;
x[i=1] = the (i=1)th number in the ordered series 
of numbers; and
i = the integer part of the product of 0.98 and n.

    (b) The 3-year average 98th percentile is then calculated 
by averaging the annual 98th percentiles:

                               Equation 7
[GRAPHIC] [TIFF OMITTED] TR18JY97.007

    (c) The 3-year average 98th percentile is rounded 
according to the conventions in section 2.3 of this appendix before a 
comparison with the standard is made.

 Example 4--Ambient Monitoring Site With Every-Day Sampling That Meets 
             the Primary 24-Hour PM2.5 Standard.

    a. In each year of a particular 3 year period, varying numbers of 
daily PM2.5 values (e.g., 281, 304, and 296) out of a 
possible 365 values were recorded at a particular site with the 
following ranked values (in g/m3):

                                  Table 3--Ordered Monitoring Data For 3 Years
----------------------------------------------------------------------------------------------------------------
               Year 1                                Year 2                                Year 3
----------------------------------------------------------------------------------------------------------------
      j rank            Xj value            j rank            Xj value            j rank            Xj value
----------------------------------------------------------------------------------------------------------------
           275               57.9                296               54.3                290               66.0
           276               59.0                297               57.1                291               68.4
           277               62.2                298               63.0                292               69.8
----------------------------------------------------------------------------------------------------------------

    b. Using Equation 6, the 98th percentile values for each 
year are calculated as follows:
[GRAPHIC] [TIFF OMITTED] TR18JY97.008

[GRAPHIC] [TIFF OMITTED] TR18JY97.009

[GRAPHIC] [TIFF OMITTED] TR18JY97.010

    c.1. Using Equation 7, the 3-year average 98th percentile 
is calculated as follows:
[GRAPHIC] [TIFF OMITTED] TR18JY97.011

    2. Therefore, this site meets the 24-hour PM2.5 standard.
    3.0 Comparisons with the PM10 Standards.
    3.1 Annual PM10 Standard.
    (a) The annual PM10 standard is met when the 3-year 
average of the annual mean PM10 concentrations at each 
monitoring site is less than or equal to 50 g/m3. 
The 3-year average of the annual means is determined by averaging 
quarterly means to obtain annual mean PM10 concentrations for 
3 consecutive, complete years at each monitoring site. The steps can be 
summarized as follows:
    (1) Average 24-hour measurements to obtain a quarterly mean.

[[Page 127]]

    (2) Average quarterly means to obtain an annual mean.
    (3) Average annual means to obtain a 3-year mean.
    (b) For the annual PM10 standard, a year meets data 
completeness requirements when at least 75 percent of the scheduled 
sampling days for each quarter have valid data. However, years with high 
concentrations and more than a minimal amount of data (at least 11 
samples in each quarter) shall not be ignored just because they are 
comprised of quarters with less than complete data. Thus, in computing 
the 3-year average annual mean concentration, years containing quarters 
with at least 11 samples but less than 75 percent data completeness 
shall be included in the computation if the annual mean concentration 
(rounded according to the conventions of section 2.3 of this appendix) 
is greater than the level of the standard.
    (c) Situations may arise in which there are compelling reasons to 
retain years containing quarters which do not meet the data completeness 
requirement of 75 percent or the minimum number of 11 samples. The use 
of less than complete data is subject to the approval of the appropriate 
Regional Administrator.
    (d) The equations for calculating the 3-year average annual mean of 
the PM10 standard are given in section 3.5 of this appendix.
    3.2 24-Hour PM10 Standard.
    (a) The 24-hour PM10 standard is met when the 3-year 
average of the annual 99th percentile values at each 
monitoring site is less than or equal to 150 g/m3. 
This comparison shall be based on 3 consecutive, complete years of air 
quality data. A year meets data completeness requirements when at least 
75 percent of the scheduled sampling days for each quarter have valid 
data. However, years with high concentrations shall not be ignored just 
because they are comprised of quarters with less than complete data. 
Thus, in computing the 3-year average of the annual 99th 
percentile values, years containing quarters with less than 75 percent 
data completeness shall be included in the computation if the annual 
99th percentile value (rounded according to the conventions 
of section 2.3 of this appendix) is greater than the level of the 
standard.
    (b) Situations may arise in which there are compelling reasons to 
retain years containing quarters which do not meet the data completeness 
requirement. The use of less than complete data is subject to the 
approval of the appropriate Regional Administrator.
    (c) The equation for calculating the 3-year average of the annual 
99th percentile values is given in section 2.6 of this 
appendix.
    3.3 Rounding Conventions. For the annual PM10 standard, 
the 3-year average of the annual PM10 means shall be rounded 
to the nearest 1 g/m3 (decimals 0.5 and greater are 
rounded up to the next whole number, and any decimal less than 0.5 is 
rounded down to the nearest whole number). For the 24-hour 
PM10 standard, the 3-year average of the annual 
99th percentile values of PM10 shall be rounded to 
the nearest 10 g/m3 (155 g/m3 
and greater would be rounded to 160 g/m3 and 154 
g/m3 and less would be rounded to 150 g/
m3).
    3.4 Monitoring Considerations. Section 58.13 of this chapter 
specifies the required minimum frequency of sampling for 
PM10. Exceptions to the specified sampling frequencies, such 
as a reduced frequency during a season of expected low concentrations, 
are subject to the approval of the appropriate Regional Administrator. 
For making comparisons with the PM10 NAAQS, all sites meeting 
applicable requirements in part 58 of this chapter would be used.
    3.5 Equations for the Annual PM10 Standard.
    (a) An annual arithmetic mean value for PM10 is 
determined by first averaging the 24-hour values of a calendar quarter 
using the following equation:

                               Equation 8
[GRAPHIC] [TIFF OMITTED] TR18JY97.012

where:

xq,y = the mean for quarter q of year y;
nq = the number of monitored values in the quarter; and
xi,q,y = the ith value in quarter q for year y.

    (b) The following equation is then to be used for calculation of the 
annual mean:

                               Equation 9
[GRAPHIC] [TIFF OMITTED] TR18JY97.013

where:

xy = the annual mean concentration for year y, (y=1, 2, or 
3); and
xq,y = the mean for a quarter q of year y.

    (c) The 3-year average of the annual means is calculated by using 
the following equation:

                               Equation 10
[GRAPHIC] [TIFF OMITTED] TR18JY97.014

where:

x = the 3-year average of the annual means; and

xy = the annual mean for calendar year y.


[[Page 128]]



    Example 5--Ambient Monitoring Site That Does Not Meet the Annual 
                        PM10 Standard.

    a. Given data from a PM10 monitor and using Equations 8 
and 9, the annual means for PM10 are calculated for each 
year. If the annual means are 52.42, 82.17, and 63.23 g/
m3, then the 3-year average annual mean is:
[GRAPHIC] [TIFF OMITTED] TR18JY97.015

    b. Therefore, this site does not meet the annual PM10 
standard.
    3.6 Equation for the 24-Hour PM10 Standard.
    (a) When the data for a particular site and year meet the data 
completeness requirements in section 3.2 of this appendix, calculation 
of the 99th percentile is accomplished by the following 
steps. All the daily values from a particular site and year comprise a 
series of values (x1, x2, x3, ..., 
xn) that can be sorted into a series where each number is 
equal to or larger than the preceding number (x[1], 
x[2], x[3], ..., x[n]). In this case, 
x[1] is the smallest number and x[n] is the largest value. 
The 99th percentile is found from the sorted series of daily 
values which is ordered from the lowest to the highest number. Compute 
(0.99)  x  (n) as the number ``i.d'', where ``i'' is the integer part of 
the result and ``d'' is the decimal part of the result. The 
99th percentile value for year y, P0.99,y, is 
given by Equation 11:

                               Equation 11
[GRAPHIC] [TIFF OMITTED] TR18JY97.016

where:

P0.99,y = the 99th percentile for year y;

x[i=1] = the (i=1)th number in the ordered series 
of numbers; and

i = the integer part of the product of 0.99 and n.

    (b) The 3-year average 99th percentile value is then 
calculated by averaging the annual 99th percentiles:

                               Equation 12
[GRAPHIC] [TIFF OMITTED] TR18JY97.017

    (c) The 3-year average 99th percentile is rounded 
according to the conventions in section 3.3 of this appendix before a 
comparison with the standard is made.

 Example 6--Ambient Monitoring Site With Sampling Every Sixth Day That 
           Meets the Primary 24-Hour PM10 Standard.

    a. In each year of a particular 3 year period, varying numbers of 
PM10 daily values (e.g., 110, 98, and 100) out of a possible 
121 daily values were recorded at a particular site with the following 
ranked values (in g/m3):

                                  Table 4--Ordered Monitoring Data For 3 Years
----------------------------------------------------------------------------------------------------------------
               Year 1                                Year 2                                Year 3
----------------------------------------------------------------------------------------------------------------
      j rank            Xj value            j rank            Xj value            j rank            Xj value
----------------------------------------------------------------------------------------------------------------
           108                120                 96                143                 98                140
           109                128                 97                148                 99                144
           110                130                 98                150                100                147
----------------------------------------------------------------------------------------------------------------

    b. Using Equation 11, the 99th percentile values for each 
year are calculated as follows:
[GRAPHIC] [TIFF OMITTED] TR18JY97.018

[GRAPHIC] [TIFF OMITTED] TR18JY97.019


[[Page 129]]


[GRAPHIC] [TIFF OMITTED] TR18JY97.020

    c. 1. Using Equation 12, the 3-year average 99th 
percentile is calculated as follows:
[GRAPHIC] [TIFF OMITTED] TR18JY97.021

    2. Therefore, this site meets the 24-hour PM10 standard.

[62 FR 38755, July 18, 1997]



PART 51--REQUIREMENTS FOR PREPARATION, ADOPTION, AND SUBMITTAL OF IMPLEMENTATION PLANS--Table of Contents




Subparts A-E [Reserved]

                   Subpart F--Procedural Requirements

Sec.
51.100  Definitions.
51.101  Stipulations.
51.102  Public hearings.
51.103  Submission of plans, preliminary review of plans.
51.104  Revisions.
51.105  Approval of plans.

                       Subpart G--Control Strategy

51.110  Attainment and maintenance of national standards.
51.111  Description of control measures.
51.112  Demonstration of adequacy.
51.113  [Reserved]
51.114  Emissions data and projections.
51.115  Air quality data and projections.
51.116  Data availability.
51.117  Additional provisions for lead.
51.118  Stack height provisions.
51.119  Intermittent control systems.
51.120  Requirements for State Implementation Plan revisions relating to 
          new motor vehicles.
51.121  Findings and requirements for submission of State implementation 
          plan revisions relating to emissions of oxides of nitrogen.
51.122  Emissions reporting requirements for SIP revisions relating to 
          budgets for NOX emissions.

        Subpart H--Prevention of Air Pollution Emergency Episodes

51.150  Classification of regions for episode plans.
51.151  Significant harm levels.
51.152  Contingency plans.
51.153  Reevaluation of episode plans.

           Subpart I--Review of New Sources and Modifications

51.160  Legally enforceable procedures.
51.161  Public availability of information.
51.162  Identification of responsible agency.
51.163  Administrative procedures.
51.164  Stack height procedures.
51.165  Permit requirements.
51.166  Prevention of significant deterioration of air quality.

               Subpart J--Ambient Air Quality Surveillance

51.190  Ambient air quality monitoring requirements.

                     Subpart K--Source Survelliance

51.210  General.
51.211  Emission reports and recordkeeping.
51.212  Testing, inspection, enforcement, and complaints.
51.213  Transportation control measures.
51.214  Continuous emission monitoring.

                       Subpart L--Legal Authority

51.230  Requirements for all plans.
51.231  Identification of legal authority.
51.232  Assignment of legal authority to local agencies.

                Subpart M--Intergovernmental Consultation

                           Agency Designation

51.240  General plan requirements.
51.241  Nonattainment areas for carbon monoxide and ozone.
51.242  [Reserved]

[[Page 130]]

                     Subpart N--Compliance Schedules

51.260  Legally enforceable compliance schedules.
51.261  Final compliance schedules.
51.262  Extension beyond one year.

           Subpart O--Miscellaneous Plan Content Requirements

51.280  Resources.
51.281  Copies of rules and regulations.
51.285  Public notification.

                   Subpart P--Protection of Visibility

51.300  Purpose and applicability.
51.301  Definitions.
51.302  Implementation control strategies for reasonably attributable 
          visibility impairment.
51.303  Exemptions from control.
51.304  Identification of integral vistas.
51.305  Monitoring for reasonably attributable visibility impairment.
51.306  Long-term strategy requirements for reasonably attributable 
          visibility impairment.
51.307  New source review.
51.308  Regional haze program requirements.
51.309  Requirements related to the Grand Canyon Visibility Transport 
          Commission.

                           Subpart Q--Reports

                       Air Quality Data Reporting

51.320  Annual air quality data report.

               Source Emissions and State Action Reporting

51.321  Annual source emissions and State action report.
51.322  Sources subject to emissions reporting.
51.323  Reportable emissions data and information.
51.324  Progress in plan enforcement.
51.326  Reportable revisions.
51.327  Enforcement orders and other State actions.
51.328  [Reserved]

                          Subpart R--Extensions

51.341  Request for 18-month extension.

         Subpart S--Inspection/Maintenance Program Requirements

51.350  Applicability.
51.351  Enhanced I/M performance standard.
51.352  Basic I/M performance standard.
51.353  Network type and program evaluation.
51.354  Adequate tools and resources.
51.355  Test frequency and convenience.
51.356  Vehicle coverage.
51.357  Test procedures and standards.
51.358  Test equipment.
51.359  Quality control.
51.360  Waivers and compliance via diagnostic inspection.
51.361  Motorist compliance enforcement.
51.362  Motorist compliance enforcement program oversight.
51.363  Quality assurance.
51.364  Enforcement against contractors, stations and inspectors.
51.365  Data collection.
51.366  Data analysis and reporting.
51.367  Inspector training and licensing or certification.
51.368  Public information and consumer protection.
51.369  Improving repair effectiveness.
51.370  Compliance with recall notices.
51.371  On-road testing.
51.372  State Implementation Plan submissions.
51.373  Implementation deadlines.

Appendix A to Subpart S--Calibrations, Adjustments and Quality Control
Appendix B to Subpart S--Test Procedures
Appendix C to Subpart S--Steady-State Short Test Standards
Appendix D to Subpart S--Steady-State Short Test Equipment
Appendix E to Subpart S--Transient Test Driving Cycle

   Subpart T--Conformity to State or Federal Implementation Plans of 
   Transportation Plans, Programs, and Projects Developed, Funded or 
       Approved Under Title 23 U.S.C. or the Federal Transit Laws

51.390  Implementation plan revision.

                 Subpart U--Economic Incentive Programs

51.490  Applicability.
51.491  Definitions.
51.492  State program election and submittal.
51.493  State program requirements.
51.494  Use of program revenues.

Subpart W--Determining Conformity of General Federal Actions to State or 
                      Federal Implementation Plans

51.850  Prohibition.
51.851  State Implementation Plan (SIP) revision.
51.852  Definitions.
51.853  Applicability.
51.854  Conformity analysis.
51.855  Reporting requirements.
51.856  Public participation.
51.857  Frequency of conformity determinations.

[[Page 131]]

51.858  Criteria for determining conformity of general Federal actions.
51.859  Procedures for conformity determinations of general Federal 
          actions.
51.860  Mitigation of air quality impacts.

Appendixes A-K [Reserved]
Appendix L to Part 51--Example Regulations for Prevention of Air 
          Pollution Emergency Episodes
Appendix M to Part 51--Recommended Test Methods for State Implementation 
          Plans
Appendixes N-O [Reserved]
Appendix P to Part 51--Minimum Emission Monitoring Requirements
Appendixes Q-R [Reserved]
Appendix S to Part 51--Emission Offset Interpretative Ruling
Appendixes T-U [Reserved]
Appendix V to Part 51--Criteria for Determining the Completeness of Plan 
          Submissions
Appendix W to Part 51--Guideline on Air Quality Models
Appendix X to Part 51--Examples of Economic Incentive Programs

    Authority: 42 U.S.C. 7410, 7414, 7421, 7470-7479, 7491, 7492, 7601, 
and 7602.

    Source: 36 FR 22398, Nov. 25, 1971, unless otherwise noted.

Subparts A-E [Reserved]



                   Subpart F--Procedural Requirements

    Authority: 42 U.S.C. 7401, 7411, 7412, 7413, 7414, 7470-7479, 7501-
7508, 7601, and 7602.



Sec. 51.100  Definitions.

    As used in this part, all terms not defined herein will have the 
meaning given them in the Act:
    (a) Act means the Clean Air Act (42 U.S.C. 7401 et seq., as amended 
by Pub. L. 91-604, 84 Stat. 1676 Pub. L. 95-95, 91 Stat., 685 and Pub. 
L. 95-190, 91 Stat., 1399.)
    (b) Administrator means the Administrator of the Environmental 
Protection Agency (EPA) or an authorized representative.
    (c) Primary standard means a national primary ambient air quality 
standard promulgated pursuant to section 109 of the Act.
    (d) Secondary standard means a national secondary ambient air 
quality standard promulgated pursuant to section 109 of the Act.
    (e) National standard means either a primary or secondary standard.
    (f) Owner or operator means any person who owns, leases, operates, 
controls, or supervises a facility, building, structure, or installation 
which directly or indirectly result or may result in emissions of any 
air pollutant for which a national standard is in effect.
    (g) Local agency means any local government agency other than the 
State agency, which is charged with responsibility for carrying out a 
portion of the plan.
    (h) Regional Office means one of the ten (10) EPA Regional Offices.
    (i) State agency means the air pollution control agency primarily 
responsible for development and implementation of a plan under the Act.
    (j) Plan means an implementation plan approved or promulgated under 
section 110 of 172 of the Act.
    (k) Point source means the following:
    (1) For particulate matter, sulfur oxides, carbon monoxide, volatile 
organic compounds (VOC) and nitrogen dioxide--
    (i) Any stationary source the actual emissions of which are in 
excess of 90.7 metric tons (100 tons) per year of the pollutant in a 
region containing an area whose 1980 urban place population, as defined 
by the U.S. Bureau of the Census, was equal to or greater than 1 
million.
    (ii) Any stationary source the actual emissions of which are in 
excess of 22.7 metric tons (25 tons) per year of the pollutant in a 
region containing an area whose 1980 urban place population, as defined 
by the U.S. Bureau of the Census, was less than 1 million; or
    (2) For lead or lead compounds measured as elemental lead, any 
stationary source that actually emits a total of 4.5 metric tons (5 
tons) per year or more.
    (l) Area source means any small residential, governmental, 
institutional, commercial, or industrial fuel combustion operations; 
onsite solid waste disposal facility; motor vehicles, aircraft vessels, 
or other transportation facilities or other miscellaneous sources 
identified through inventory techniques similar to those described in 
the ``AEROS Manual series, Vol. II AEROS

[[Page 132]]

User's Manual,'' EPA-450/2-76-029 December 1976.
    (m) Region means an area designated as an air quality control region 
(AQCR) under section 107(c) of the Act.
    (n) Control strategy means a combination of measures designated to 
achieve the aggregate reduction of emissions necessary for attainment 
and maintenance of national standards including, but not limited to, 
measures such as:
    (1) Emission limitations.
    (2) Federal or State emission charges or taxes or other economic 
incentives or disincentives.
    (3) Closing or relocation of residential, commercial, or industrial 
facilities.
    (4) Changes in schedules or methods of operation of commercial or 
industrial facilities or transportation systems, including, but not 
limited to, short-term changes made in accordance with standby plans.
    (5) Periodic inspection and testing of motor vehicle emission 
control systems, at such time as the Administrator determines that such 
programs are feasible and practicable.
    (6) Emission control measures applicable to in-use motor vehicles, 
including, but not limited to, measures such as mandatory maintenance, 
installation of emission control devices, and conversion to gaseous 
fuels.
    (7) Any transportation control measure including those 
transportation measures listed in section 108(f) of the Clean Air Act as 
amended.
    (8) Any variation of, or alternative to any measure delineated 
herein.
    (9) Control or prohibition of a fuel or fuel additive used in motor 
vehicles, if such control or prohibition is necessary to achieve a 
national primary or secondary air quality standard and is approved by 
the Administrator under section 211(c)(4)(C) of the Act.
    (o) Reasonably available control technology (RACT) means devices, 
systems, process modifications, or other apparatus or techniques that 
are reasonably available taking into account:
    (1) The necessity of imposing such controls in order to attain and 
maintain a national ambient air quality standard;
    (2) The social, environmental, and economic impact of such controls; 
and
    (3) Alternative means of providing for attainment and maintenance of 
such standard. (This provision defines RACT for the purposes of 
Sec. 51.341(b) only.)
    (p) Compliance schedule means the date or dates by which a source or 
category of sources is required to comply with specific emission 
limitations contained in an implementation plan and with any increments 
of progress toward such compliance.
    (q) Increments of progress means steps toward compliance which will 
be taken by a specific source, including:
    (1) Date of submittal of the source's final control plan to the 
appropriate air pollution control agency;
    (2) Date by which contracts for emission control systems or process 
modifications will be awarded; or date by which orders will be issued 
for the purchase of component parts to accomplish emission control or 
process modification;
    (3) Date of initiation of on-site construction or installation of 
emission control equipment or process change;
    (4) Date by which on-site construction or installation of emission 
control equipment or process modification is to be completed; and
    (5) Date by which final compliance is to be achieved.
    (r) Transportation control measure means any measure that is 
directed toward reducing emissions of air pollutants from transportation 
sources. Such measures include, but are not limited to, those listed in 
section 108(f) of the Clean Air Act.
    (s) Volatile organic compounds (VOC) means any compound of carbon, 
excluding carbon monoxide, carbon dioxide, carbonic acid, metallic 
carbides or carbonates, and ammonium carbonate, which participates in 
atmospheric photochemical reactions.
    (1) This includes any such organic compound other than the 
following, which have been determined to have negligible photochemical 
reactivity: methane; ethane; methylene chloride (dichloromethane); 
1,1,1-trichloroethane (methyl chloroform); 1,1,2-trichloro-1,2,2-
trifluoroethane (CFC-113); trichlorofluoromethane (CFC-11); 
dichlorodifluoromethane (CFC-12); chlorodifluoromethane (HCFC-22); 
trifluoromethane (HFC-23); 1,2-dichloro

[[Page 133]]

1,1,2,2-tetrafluoroethane (CFC-114); chloropentafluoroethane (CFC-115); 
1,1,1-trifluoro 2,2-dichloroethane (HCFC-123); 1,1,1,2-tetrafluoroethane 
(HFC-134a); 1,1-dichloro 1-fluoroethane (HCFC-141b); 1-chloro 1,1-
difluoroethane (HCFC-142b); 2-chloro-1,1,1,2-tetrafluoroethane (HCFC-
124); pentafluoroethane (HFC-125); 1,1,2,2-tetrafluoroethane (HFC-134); 
1,1,1-trifluoroethane (HFC-143a); 1,1-difluoroethane (HFC-152a); 
parachlorobenzotrifluoride (PCBTF); cyclic, branched, or linear 
completely methylated siloxanes; acetone; perchloroethylene 
(tetrachloroethylene); 3,3-dichloro-1,1,1,2,2-pentafluoropropane (HCFC-
225ca); 1,3-dichloro-1,1,2,2,3-pentafluoropropane (HCFC-225cb); 
1,1,1,2,3,4,4,5,5,5-decafluoropentane (HFC 43-10mee); difluoromethane 
(HFC-32); ethylfluoride (HFC-161); 1,1,1,3,3,3-hexafluoropropane (HFC-
236fa); 1,1,2,2,3-pentafluoropropane (HFC-245ca); 1,1,2,3,3-
pentafluoropropane (HFC-245ea); 1,1,1,2,3-pentafluoropropane (HFC-
245eb); 1,1,1,3,3-pentafluoropropane (HFC-245fa); 1,1,1,2,3,3-
hexafluoropropane (HFC-236ea); 1,1,1,3,3-pentafluorobutane (HFC-365mfc); 
chlorofluoromethane (HCFC-31); 1 chloro-1-fluoroethane (HCFC-151a); 1,2-
dichloro-1,1,2-trifluoroethane (HCFC-123a); 1,1,1,2,2,3,3,4,4-
nonafluoro-4-methoxy-butane (C4F9OCH3); 
2-(difluoromethoxymethyl)-1,1,1,2,3,3,3-heptafluoropropane 
((CF3)2CFCF2OCH3); 1-ethoxy-
1,1,2,2,3,3,4,4,4-nonafluorobutane 
(C4F9OC2H5); 2-
(ethoxydifluoromethyl)-1,1,1,2,3,3,3-heptafluoropropane 
((CF3)2CFCF2OC2H5)
; methyl acetate and perfluorocarbon compounds which fall into these 
classes:
    (i) Cyclic, branched, or linear, completely fluorinated alkanes;
    (ii) Cyclic, branched, or linear, completely fluorinated ethers with 
no unsaturations;
    (iii) Cyclic, branched, or linear, completely fluorinated tertiary 
amines with no unsaturations; and
    (iv) Sulfur containing perfluorocarbons with no unsaturations and 
with sulfur bonds only to carbon and fluorine.
    (2) For purposes of determining compliance with emissions limits, 
VOC will be measured by the test methods in the approved State 
implementation plan (SIP) or 40 CFR part 60, appendix A, as applicable. 
Where such a method also measures compounds with negligible 
photochemical reactivity, these negligibility-reactive compounds may be 
excluded as VOC if the amount of such compounds is accurately 
quantified, and such exclusion is approved by the enforcement authority.
    (3) As a precondition to excluding these compounds as VOC or at any 
time thereafter, the enforcement authority may require an owner or 
operator to provide monitoring or testing methods and results 
demonstrating, to the satisfaction of the enforcement authority, the 
amount of negligibly-reactive compounds in the source's emissions.
    (4) For purposes of Federal enforcement for a specific source, the 
EPA shall use the test methods specified in the applicable EPA-approved 
SIP, in a permit issued pursuant to a program approved or promulgated 
under title V of the Act, or under 40 CFR part 51, subpart I or appendix 
S, or under 40 CFR parts 52 or 60. The EPA shall not be bound by any 
State determination as to appropriate methods for testing or monitoring 
negligibly-reactive compounds if such determination is not reflected in 
any of the above provisions.
    (t)-(w) [Reserved]
    (x) Time period means any period of time designated by hour, month, 
season, calendar year, averaging time, or other suitable 
characteristics, for which ambient air quality is estimated.
    (y) Variance means the temporary deferral of a final compliance date 
for an individual source subject to an approved regulation, or a 
temporary change to an approved regulation as it applies to an 
individual source.
    (z) Emission limitation and emission standard mean a requirement 
established by a State, local government, or the Administrator which 
limits the quantity, rate, or concentration of emissions of air 
pollutants on a continuous basis, including any requirements

[[Page 134]]

which limit the level of opacity, prescribe equipment, set fuel 
specifications, or prescribe operation or maintenance procedures for a 
source to assure continuous emission reduction.
    (aa) Capacity factor means the ratio of the average load on a 
machine or equipment for the period of time considered to the capacity 
rating of the machine or equipment.
    (bb) Excess emissions means emissions of an air pollutant in excess 
of an emission standard.
    (cc) Nitric acid plant means any facility producing nitric acid 30 
to 70 percent in strength by either the pressure or atmospheric pressure 
process.
    (dd) Sulfuric acid plant means any facility producing sulfuric acid 
by the contact process by burning elemental sulfur, alkylation acid, 
hydrogen sulfide, or acid sludge, but does not include facilities where 
conversion to sulfuric acid is utilized primarily as a means of 
preventing emissions to the atmosphere of sulfur dioxide or other sulfur 
compounds.
    (ee) Fossil fuel-fired steam generator means a furnance or bioler 
used in the process of burning fossil fuel for the primary purpose of 
producing steam by heat transfer.
    (ff) Stack means any point in a source designed to emit solids, 
liquids, or gases into the air, including a pipe or duct but not 
including flares.
    (gg) A stack in existence means that the owner or operator had (1) 
begun, or caused to begin, a continuous program of physical on-site 
construction of the stack or (2) entered into binding agreements or 
contractual obligations, which could not be cancelled or modified 
without substantial loss to the owner or operator, to undertake a 
program of construction of the stack to be completed within a reasonable 
time.
    (hh)(1) Dispersion technique means any technique which attempts to 
affect the concentration of a pollutant in the ambient air by:
    (i) Using that portion of a stack which exceeds good engineering 
practice stack height:
    (ii) Varying the rate of emission of a pollutant according to 
atmospheric conditions or ambient concentrations of that pollutant; or
    (iii) Increasing final exhaust gas plume rise by manipulating source 
process parameters, exhaust gas parameters, stack parameters, or 
combining exhaust gases from several existing stacks into one stack; or 
other selective handling of exhaust gas streams so as to increase the 
exhaust gas plume rise.
    (2) The preceding sentence does not include:
    (i) The reheating of a gas stream, following use of a pollution 
control system, for the purpose of returning the gas to the temperature 
at which it was originally discharged from the facility generating the 
gas stream;
    (ii) The merging of exhaust gas streams where:
    (A) The source owner or operator demonstrates that the facility was 
originally designed and constructed with such merged gas streams;
    (B) After July 8, 1985 such merging is part of a change in operation 
at the facility that includes the installation of pollution controls and 
is accompanied by a net reduction in the allowable emissions of a 
pollutant. This exclusion from the definition of dispersion techniques 
shall apply only to the emission limitation for the pollutant affected 
by such change in operation; or
    (C) Before July 8, 1985, such merging was part of a change in 
operation at the facility that included the installation of emissions 
control equipment or was carried out for sound economic or engineering 
reasons. Where there was an increase in the emission limitation or, in 
the event that no emission limitation was in existence prior to the 
merging, an increase in the quantity of pollutants actually emitted 
prior to the merging, the reviewing agency shall presume that merging 
was significantly motivated by an intent to gain emissions credit for 
greater dispersion. Absent a demonstration by the source owner or 
operator that merging was not significantly motivated by such intent, 
the reviewing agency shall deny credit for the effects of such merging 
in calculating the allowable emissions for the source;
    (iii) Smoke management in agricultural or silvicultural prescribed 
burning programs;

[[Page 135]]

    (iv) Episodic restrictions on residential woodburning and open 
burning; or
    (v) Techniques under Sec. 51.100(hh)(1)(iii) which increase final 
exhaust gas plume rise where the resulting allowable emissions of sulfur 
dioxide from the facility do not exceed 5,000 tons per year.
    (ii) Good engineering practice (GEP) stack height means the greater 
of:
    (1) 65 meters, measured from the ground-level elevation at the base 
of the stack:
    (2)(i) For stacks in existence on January 12, 1979, and for which 
the owner or operator had obtained all applicable permits or approvals 
required under 40 CFR parts 51 and 52.

Hg = 2.5H,


provided the owner or operator produces evidence that this equation was 
actually relied on in establishing an emission limitation:
    (ii) For all other stacks,

Hg = H + 1.5L

where:

Hg = good engineering practice stack height, measured from 
the ground-level elevation at the base of the stack,
H = height of nearby structure(s) measured from the ground-level 
elevation at the base of the stack.
L = lesser dimension, height or projected width, of nearby structure(s)


provided that the EPA, State or local control agency may require the use 
of a field study or fluid model to verify GEP stack height for the 
source; or
    (3) The height demonstrated by a fluid model or a field study 
approved by the EPA State or local control agency, which ensures that 
the emissions from a stack do not result in excessive concentrations of 
any air pollutant as a result of atmospheric downwash, wakes, or eddy 
effects created by the source itself, nearby structures or nearby 
terrain features.
    (jj) Nearby as used in Sec. 51.100(ii) of this part is defined for a 
specific structure or terrain feature and
    (1) For purposes of applying the formulae provided in 
Sec. 51.100(ii)(2) means that distance up to five times the lesser of 
the height or the width dimension of a structure, but not greater than 
0.8 km (\1/2\ mile), and
    (2) For conducting demonstrations under Sec. 51.100(ii)(3) means not 
greater than 0.8 km (\1/2\ mile), except that the portion of a terrain 
feature may be considered to be nearby which falls within a distance of 
up to 10 times the maximum height (Ht) of the feature, not to 
exceed 2 miles if such feature achieves a height (Ht) 0.8 km 
from the stack that is at least 40 percent of the GEP stack height 
determined by the formulae provided in Sec. 51.100(ii)(2)(ii) of this 
part or 26 meters, whichever is greater, as measured from the ground-
level elevation at the base of the stack. The height of the structure or 
terrain feature is measured from the ground-level elevation at the base 
of the stack.
    (kk) Excessive concentration is defined for the purpose of 
determining good engineering practice stack height under 
Sec. 51.100(ii)(3) and means:
    (1) For sources seeking credit for stack height exceeding that 
established under Sec. 51.100(ii)(2) a maximum ground-level 
concentration due to emissions from a stack due in whole or part to 
downwash, wakes, and eddy effects produced by nearby structures or 
nearby terrain features which individually is at least 40 percent in 
excess of the maximum concentration experienced in the absence of such 
downwash, wakes, or eddy effects and which contributes to a total 
concentration due to emissions from all sources that is greater than an 
ambient air quality standard. For sources subject to the prevention of 
significant deterioration program (40 CFR 51.166 and 52.21), an 
excessive concentration alternatively means a maximum ground-level 
concentration due to emissions from a stack due in whole or part to 
downwash, wakes, or eddy effects produced by nearby structures or nearby 
terrain features which individually is at least 40 percent in excess of 
the maximum concentration experienced in the absence of such downwash, 
wakes, or eddy effects and greater than a prevention of significant 
deterioration increment. The allowable emission rate to be used in 
making demonstrations under this part shall be prescribed by the new 
source performance standard that is applicable to the source category 
unless the owner or operator demonstrates that this emission

[[Page 136]]

rate is infeasible. Where such demonstrations are approved by the 
authority administering the State implementation plan, an alternative 
emission rate shall be established in consultation with the source owner 
or operator.
    (2) For sources seeking credit after October 11, 1983, for increases 
in existing stack heights up to the heights established under 
Sec. 51.100(ii)(2), either (i) a maximum ground-level concentration due 
in whole or part to downwash, wakes or eddy effects as provided in 
paragraph (kk)(1) of this section, except that the emission rate 
specified by any applicable State implementation plan (or, in the 
absence of such a limit, the actual emission rate) shall be used, or 
(ii) the actual presence of a local nuisance caused by the existing 
stack, as determined by the authority administering the State 
implementation plan; and
    (3) For sources seeking credit after January 12, 1979 for a stack 
height determined under Sec. 51.100(ii)(2) where the authority 
administering the State implementation plan requires the use of a field 
study or fluid model to verify GEP stack height, for sources seeking 
stack height credit after November 9, 1984 based on the aerodynamic 
influence of cooling towers, and for sources seeking stack height credit 
after December 31, 1970 based on the aerodynamic influence of structures 
not adequately represented by the equations in Sec. 51.100(ii)(2), a 
maximum ground-level concentration due in whole or part to downwash, 
wakes or eddy effects that is at least 40 percent in excess of the 
maximum concentration experienced in the absence of such downwash, 
wakes, or eddy effects.
    (ll)-(mm) [Reserved]
    (nn) Intermittent control system (ICS) means a dispersion technique 
which varies the rate at which pollutants are emitted to the atmosphere 
according to meteorological conditions and/or ambient concentrations of 
the pollutant, in order to prevent ground-level concentrations in excess 
of applicable ambient air quality standards. Such a dispersion technique 
is an ICS whether used alone, used with other dispersion techniques, or 
used as a supplement to continuous emission controls (i.e., used as a 
supplemental control system).
    (oo) Particulate matter means any airborne finely divided solid or 
liquid material with an aerodynamic diameter smaller than 100 
micrometers.
    (pp) Particulate matter emissions means all finely divided solid or 
liquid material, other than uncombined water, emitted to the ambient air 
as measured by applicable reference methods, or an equivalent or 
alternative method, specified in this chapter, or by a test method 
specified in an approved State implementation plan.
    (qq) PM10 means particulate matter with an aerodynamic 
diameter less than or equal to a nominal 10 micrometers as measured by a 
reference method based on appendix J of part 50 of this chapter and 
designated in accordance with part 53 of this chapter or by an 
equivalent method designated in accordance with part 53 of this chapter.
    (rr) PM10 emissions means finely divided solid or liquid 
material, with an aerodynamic diameter less than or equal to a nominal 
10 micrometers emitted to the ambient air as measured by an applicable 
reference method, or an equivalent or alternative method, specified in 
this chapter or by a test method specified in an approved State 
implementation plan.
    (ss) Total suspended particulate means particulate matter as 
measured by the method described in appendix B of part 50 of this 
chapter.

[51 FR 40661, Nov. 7, 1986, as amended at 52 FR 24712, July 1, 1987; 57 
FR 3945, Feb. 3, 1992; 61 FR 4590, Feb. 7, 1996; 61 FR 16060, Apr. 11, 
1996; 61 FR 30162, June 14, 1996; 61 FR 52850, Oct. 8, 1996; 62 FR 
44903, Aug. 25, 1997; 63 FR 9151, Feb. 24, 1998; 63 FR 17333, Apr. 9, 
1998]



Sec. 51.101  Stipulations.

    Nothing in this part will be construed in any manner:
    (a) To encourage a State to prepare, adopt, or submit a plan which 
does not provide for the protection and enhancement of air quality so as 
to promote the public health and welfare and productive capacity.
    (b) To encourage a State to adopt any particular control strategy 
without taking into consideration the cost-effectiveness of such control 
strategy

[[Page 137]]

in relation to that of alternative control strategies.
    (c) To preclude a State from employing techniques other than those 
specified in this part for purposes of estimating air quality or 
demonstrating the adequacy of a control strategy, provided that such 
other techniques are shown to be adequate and appropriate for such 
purposes.
    (d) To encourage a State to prepare, adopt, or submit a plan without 
taking into consideration the social and economic impact of the control 
strategy set forth in such plan, including, but not limited to, impact 
on availability of fuels, energy, transportation, and employment.
    (e) To preclude a State from preparing, adopting, or submitting a 
plan which provides for attainment and maintenance of a national 
standard through the application of a control strategy not specifically 
identified or described in this part.
    (f) To preclude a State or political subdivision thereof from 
adopting or enforcing any emission limitations or other measures or 
combinations thereof to attain and maintain air quality better than that 
required by a national standard.
    (g) To encourage a State to adopt a control strategy uniformly 
applicable throughout a region unless there is no satisfactory 
alternative way of providing for attainment and maintenance of a 
national standard throughout such region.

[61 FR 30163, June 14, 1996]



Sec. 51.102  Public hearings.

    (a) Except as otherwise provided in paragraph (c) of this section, 
States must conduct one or more public hearings on the following prior 
to adoption and submission to EPA of:
    (1) Any plan or revision of it required by Sec. 51.104(a).
    (2) Any individual compliance schedule under (Sec. 51.260).
    (3) Any revision under Sec. 51.104(d).
    (b) Separate hearings may be held for plans to implement primary and 
secondary standards.
    (c) No hearing will be required for any change to an increment of 
progress in an approved individual compliance schedule unless such 
change is likely to cause the source to be unable to comply with the 
final compliance date in the schedule. The requirements of Secs. 51.104 
and 51.105 will be applicable to such schedules, however.
    (d) Any hearing required by paragraph (a) of this section will be 
held only after reasonable notice, which will be considered to include, 
at least 30 days prior to the date of such hearing(s):
    (1) Notice given to the public by prominent advertisement in the 
area affected announcing the date(s), time(s), and place(s) of such 
hearing(s);
    (2) Availability of each proposed plan or revision for public 
inspection in at least one location in each region to which it will 
apply, and the availability of each compliance schedule for public 
inspection in at least one location in the region in which the affected 
source is located;
    (3) Notification to the Administrator (through the appropriate 
Regional Office);
    (4) Notification to each local air pollution control agency which 
will be significantly impacted by such plan, schedule or revision;
    (5) In the case of an interstate region, notification to any other 
States included, in whole or in part, in the regions which are 
significantly impacted by such plan or schedule or revision.
    (e) The State must prepare and retain, for inspection by the 
Administrator upon request, a record of each hearing. The record must 
contain, as a minimum, a list of witnesses together with the text of 
each presentation.
    (f) The State must submit with the plan, revision, or schedule a 
certification that the hearing required by paragraph (a) of this section 
was held in accordance with the notice required by paragraph (d) of this 
section.
    (g) Upon written application by a State agency (through the 
appropriate Regional Office), the Administrator may approve State 
procedures for public hearings. The following criteria apply:
    (1) Procedures approved under this section shall be deemed to 
satisfy the requirement of this part regarding public hearings.
    (2) Procedures different from this part may be approved if they--

[[Page 138]]

    (i) Ensure public participation in matters for which hearings are 
required; and
    (ii) Provide adequate public notification of the opportunity to 
participate.
    (3) The Administrator may impose any conditions on approval he or 
she deems necessary.

[36 FR 22938, Nov. 25, 1971, as amended at 65 FR 8657, Feb. 22, 2000]



Sec. 51.103  Submission of plans, preliminary review of plans.

    (a) The State makes an official plan submission to EPA only when the 
submission conforms to the requirements of appendix V to this part, and 
the State delivers five copies of the plan to the appropriate Regional 
Office, with a letter giving notice of such action.
    (b) Upon request of a State, the Administrator will provide 
preliminary review of a plan or portion thereof submitted in advance of 
the date such plan is due. Such requests must be made in writing to the 
appropriate Regional Office and must be accompanied by five copies of 
the materials to be reviewed. Requests for preliminary review do not 
relieve a State of the responsibility of adopting and submitting plans 
in accordance with prescribed due dates.

[51 FR 40661, Nov. 7, 1986, as amended at 55 FR 5830, Feb. 16, 1990; 63 
FR 9151, Feb. 24, 1998]



Sec. 51.104  Revisions.

    (a) States may revise the plan from time to time consistent with the 
requirements applicable to implementation plans under this part.
    (b) The States must submit any revision of any regulation or any 
compliance schedule under paragraph (c) of this section to the 
Administrator no later than 60 days after its adoption.
    (c) EPA will approve revisions only after applicable hearing 
requirements of Sec. 51.102 have been satisfied.
    (d) In order for a variance to be considered for approval as a 
revision to the State implementation plan, the State must submit it in 
accordance with the requirements of this section.

[51 FR 40661, Nov. 7, 1986, as amended at 61 FR 16060, Apr. 11, 1996]



Sec. 51.105  Approval of plans.

    Revisions of a plan, or any portion thereof, will not be considered 
part of an applicable plan until such revisions have been approved by 
the Administrator in accordance with this part.

[51 FR 40661, Nov. 7, 1986, as amended at 60 FR 33922, June 29, 1995]



                       Subpart G--Control Strategy

    Source: 51 FR 40665, Nov. 7, 1986, unless otherwise noted.



Sec. 51.110  Attainment and maintenance of national standards.

    (a) Each plan providing for the attainment of a primary or secondary 
standard must specify the projected attainment date.
    (b)-(f) [Reserved]
    (g) During developing of the plan, EPA encourages States to identify 
alternative control strategies, as well as the costs and benefits of 
each such alternative for attainment or maintenance of the national 
standard.

[51 FR 40661 Nov. 7, 1986 as amended at 61 FR 16060, Apr. 11, 1996; 61 
FR 30163, June 14, 1996]



Sec. 51.111  Description of control measures.

    Each plan must set forth a control strategy which includes the 
following:
    (a) A description of enforcement methods including, but not limited 
to:
    (1) Procedures for monitoring compliance with each of the selected 
control measures,
    (2) Procedures for handling violations, and
    (3) A designation of agency responsibility for enforcement of 
implementation.
    (b) [Reserved]

[51 FR 40665, Nov. 7, 1986, as amended at 60 FR 33922, June 29, 1995]



Sec. 51.112  Demonstration of adequacy.

    (a) Each plan must demonstrate that the measures, rules, and 
regulations contained in it are adequate to provide for the timely 
attainment and maintenance of the national standard that it implements.
    (1) The adequacy of a control strategy shall be demonstrated by 
means of

[[Page 139]]

applicable air quality models, data bases, and other requirements 
specified in appendix W of this part (Guideline on Air Quality Models).
    (2) Where an air quality model specified in appendix W of this part 
(Guideline on Air Quality Models) is inappropriate, the model may be 
modified or another model substituted. Such a modification or 
substitution of a model may be made on a case-by-case basis or, where 
appropriate, on a generic basis for a specific State program. Written 
approval of the Administrator must be obtained for any modification or 
substitution. In addition, use of a modified or substituted model must 
be subject to notice and opportunity for public comment under procedures 
set forth in Sec. 51.102.
    (b) The demonstration must include the following:
    (1) A summary of the computations, assumptions, and judgments used 
to determine the degree of reduction of emissions (or reductions in the 
growth of emissions) that will result from the implementation of the 
control strategy.
    (2) A presentation of emission levels expected to result from 
implementation of each measure of the control strategy.
    (3) A presentation of the air quality levels expected to result from 
implementation of the overall control strategy presented either in 
tabular form or as an isopleth map showing expected maximum pollutant 
concentrations.
    (4) A description of the dispersion models used to project air 
quality and to evaluate control strategies.
    (5) For interstate regions, the analysis from each constituent State 
must, where practicable, be based upon the same regional emission 
inventory and air quality baseline.

[51 FR 40665, Nov. 7, 1986, as amended at 58 FR 38821, July 20, 1993; 60 
FR 40468, Aug. 9, 1995; 61 FR 41840, Aug. 12, 1996]



Sec. 51.113  [Reserved]



Sec. 51.114  Emissions data and projections.

    (a) Except for lead, each plan must contain a detailed inventory of 
emissions from point and area sources. Lead requirements are specified 
in Sec. 51.117. The inventory must be based upon measured emissions or, 
where measured emissions are not available, documented emission factors.
    (b) Each plan must contain a summary of emission levels projected to 
result from application of the new control strategy.
    (c) Each plan must identify the sources of the data used in the 
projection of emissions.



Sec. 51.115  Air quality data and projections.

    (a) Each plan must contain a summary of data showing existing air 
quality.
    (b) Each plan must:
    (1) Contain a summary of air quality concentrations expected to 
result from application of the control strategy, and
    (2) Identify and describe the dispersion model, other air quality 
model, or receptor model used.
    (c) Actual measurements of air quality must be used where available 
if made by methods specified in appendix C to part 58 of this chapter. 
Estimated air quality using appropriate modeling techniques may be used 
to supplement measurements.
    (d) For purposes of developing a control strategy, background 
concentration shall be taken into consideration with respect to 
particulate matter. As used in this subpart, background concentration is 
that portion of the measured ambient levels that cannot be reduced by 
controlling emissions from man-made sources.
    (e) In developing an ozone control strategy for a particular area, 
background ozone concentrations and ozone transported into an area must 
be considered. States may assume that the ozone standard will be 
attained in upwind areas.



Sec. 51.116  Data availability.

    (a) The State must retain all detailed data and calculations used in 
the preparation of each plan or each plan revision, and make them 
available for public inspection and submit them to the Administrator at 
his request.
    (b) The detailed data and calculations used in the preparation of 
plan revisions are not considered a part of the plan.

[[Page 140]]

    (c) Each plan must provide for public availability of emission data 
reported by source owners or operators or otherwise obtained by a State 
or local agency. Such emission data must be correlated with applicable 
emission limitations or other measures. As used in this paragraph, 
correlated means presented in such a manner as to show the relationship 
between measured or estimated amounts of emissions and the amounts of 
such emissions allowable under the applicable emission limitations or 
other measures.



Sec. 51.117  Additional provisions for lead.

    In addition to other requirements in Secs. 51.100 through 51.116 the 
following requirements apply to lead. To the extent they conflict, there 
requirements are controlling over those of the proceeding sections.
    (a) Control strategy demonstration. Each plan must contain a 
demonstration showing that the plan will attain and maintain the 
standard in the following areas:
    (1) Areas in the vicinity of the following point sources of lead: 
Primary lead smelters, Secondary lead smelters, Primary copper smelters, 
Lead gasoline additive plants, Lead-acid storage battery manufacturing 
plants that produce 2,000 or more batteries per day. Any other 
stationary source that actually emits 25 or more tons per year of lead 
or lead compounds measured as elemental lead.
    (2) Any other area that has lead air concentrations in excess of the 
national ambient air quality standard concentration for lead, measured 
since January 1, 1974.
    (b) Time period for demonstration of adequacy. The demonstration of 
adequacy of the control strategy required under Sec. 51.112 may cover a 
longer period if allowed by the appropriate EPA Regional Administrator.
    (c) Special modeling provisions. (1) For urbanized areas with 
measured lead concentrations in excess of 4.0 g/m\3\, quarterly 
mean measured since January 1, 1974, the plan must employ the modified 
rollback model for the demonstration of attainment as a minimum, but may 
use an atmospheric dispersion model if desired, consistent with 
requirements contained in Sec. 51.112(a). If a proportional model is 
used, the air quality data should be the same year as the emissions 
inventory required under the paragraph e.
    (2) For each point source listed in Sec. 51.117(a), that plan must 
employ an atmospheric dispersion model for demonstration of attainment, 
consistent with requirements contained in Sec. 51.112(a).
    (3) For each area in the vicinity of an air quality monitor that has 
recorded lead concentrations in excess of the lead national standard 
concentration, the plan must employ the modified rollback model as a 
minimum, but may use an atmospheric dispersion model if desired for the 
demonstration of attainment, consistent with requirements contained in 
Sec. 51.112(a).
    (d) Air quality data and projections. (1) Each State must submit to 
the appropriate EPA Regional Office with the plan, but not part of the 
plan, all lead air quality data measured since January 1, 1974. This 
requirement does not apply if the data has already been submitted.
    (2) The data must be submitted in accordance with the procedures and 
data forms specified in Chapter 3.4.0 of the ``AEROS User's Manual'' 
concerning storage and retrieval of aerometric data (SAROAD) except 
where the Regional Administrator waives this requirement.
    (3) If additional lead air quality data are desired to determine 
lead air concentrations in areas suspected of exceeding the lead 
national ambient air quality standard, the plan may include data from 
any previously collected filters from particulate matter high volume 
samplers. In determining the lead content of the filters for control 
strategy demonstration purposes, a State may use, in addition to the 
reference method, X-ray fluorescence or any other method approved by the 
Regional Administrator.
    (e) Emissions data. (1) The point source inventory on which the 
summary of the baseline lead emissions inventory is based must contain 
all sources that emit five or more tons of lead per year.
    (2) Each State must submit lead emissions data to the appropriate 
EPA Regional Office with the original plan.

[[Page 141]]

The submission must be made with the plan, but not as part of the plan, 
and must include emissions data and information related to point and 
area source emissions. The emission data and information should include 
the information identified in the Hazardous and Trace Emissions System 
(HATREMS) point source coding forms for all point sources and the area 
source coding forms for all sources that are not point sources, but need 
not necessarily be in the format of those forms.

[41 FR 18388, May 3, 1976, as amended at 58 FR 38822, July 20, 1993]



Sec. 51.118  Stack height provisions.

    (a) The plan must provide that the degree of emission limitation 
required of any source for control of any air pollutant must not be 
affected by so much of any source's stack height that exceeds good 
engineering practice or by any other dispersion technique, except as 
provided in Sec. 51.118(b). The plan must provide that before a State 
submits to EPA a new or revised emission limitation that is based on a 
good engineering practice stack height that exceeds the height allowed 
by Sec. 51.100(ii) (1) or (2), the State must notify the public of the 
availabilty of the demonstration study and must provide opportunity for 
a public hearing on it. This section does not require the plan to 
restrict, in any manner, the actual stack height of any source.
    (b) The provisions of Sec. 51.118(a) shall not apply to (1) stack 
heights in existence, or dispersion techniques implemented on or before 
December 31, 1970, except where pollutants are being emitted from such 
stacks or using such dispersion techniques by sources, as defined in 
section 111(a)(3) of the Clean Air Act, which were constructed, or 
reconstructed, or for which major modifications, as defined in 
Secs. 51.165(a)(1)(v)(A), 51.166(b)(2)(i) and 52.21(b)(2)(i), were 
carried out after December 31, 1970; or (2) coal-fired steam electric 
generating units subject to the provisions of section 118 of the Clean 
Air Act, which commenced operation before July 1, 1957, and whose stacks 
were construced under a construction contract awarded before February 8, 
1974.



Sec. 51.119  Intermittent control systems.

    (a) The use of an intermittent control system (ICS) may be taken 
into account in establishing an emission limitation for a pollutant 
under a State implementation plan, provided:
    (1) The ICS was implemented before December 31, 1970, according to 
the criteria specified in Sec. 51.119(b).
    (2) The extent to which the ICS is taken into account is limited to 
reflect emission levels and associated ambient pollutant concentrations 
that would result if the ICS was the same as it was before December 31, 
1970, and was operated as specified by the operating system of the ICS 
before December 31, 1970.
    (3) The plan allows the ICS to compensate only for emissions from a 
source for which the ICS was implemented before December 31, 1970, and, 
in the event the source has been modified, only to the extent the 
emissions correspond to the maximum capacity of the source before 
December 31, 1970. For purposes of this paragraph, a source for which 
the ICS was implemented is any particular structure or equipment the 
emissions from which were subject to the ICS operating procedures.
    (4) The plan requires the continued operation of any constant 
pollution control system which was in use before December 31, 1970, or 
the equivalent of that system.
    (5) The plan clearly defines the emission limits affected by the ICS 
and the manner in which the ICS is taken into account in establishing 
those limits.
    (6) The plan contains requirements for the operation and maintenance 
of the qualifying ICS which, together with the emission limitations and 
any other necessary requirements, will assure that the national ambient 
air quality standards and any applicable prevention of significant 
deterioration increments will be attained and maintained. These 
requirements shall include, but not necessarily be limited to, the 
following:
    (i) Requirements that a source owner or operator continuously 
operate and maintain the components of the ICS specified at 
Sec. 51.119(b)(3) (ii)-(iv) in a manner which assures that the ICS is

[[Page 142]]

at least as effective as it was before December 31, 1970. The air 
quality monitors and meteorological instrumentation specified at 
Sec. 51.119(b) may be operated by a local authority or other entity 
provided the source has ready access to the data from the monitors and 
instrumentation.
    (ii) Requirements which specify the circumstances under which, the 
extent to which, and the procedures through which, emissions shall be 
curtailed through the activation of ICS.
    (iii) Requirements for recordkeeping which require the owner or 
operator of the source to keep, for periods of at least 3 years, records 
of measured ambient air quality data, meteorological information 
acquired, and production data relating to those processes affected by 
the ICS.
    (iv) Requirements for reporting which require the owner or operator 
of the source to notify the State and EPA within 30 days of a NAAQS 
violation pertaining to the pollutant affected by the ICS.
    (7) Nothing in this paragraph affects the applicability of any new 
source review requirements or new source performance standards contained 
in the Clean Air Act or 40 CFR subchapter C. Nothing in this paragraph 
precludes a State from taking an ICS into account in establishing 
emission limitations to any extent less than permitted by this 
paragraph.
    (b) An intermittent control system (ICS) may be considered 
implemented for a pollutant before December 31, 1970, if the following 
criteria are met:
    (1) The ICS must have been established and operational with respect 
to that pollutant prior to December 31, 1970, and reductions in 
emissions of that pollutant must have occurred when warranted by 
meteorological and ambient monitoring data.
    (2) The ICS must have been designed and operated to meet an air 
quality objective for that pollutant such as an air quality level or 
standard.
    (3) The ICS must, at a minimum, have included the following 
components prior to December 31, 1970:
    (i) Air quality monitors. An array of sampling stations whose 
location and type were consistent with the air quality objective and 
operation of the system.
    (ii) Meteorological instrumentation. A meteorological data 
acquisition network (may be limited to a single station) which provided 
meteorological prediction capabilities sufficient to determine the need 
for, and degree of, emission curtailments necessary to achieve the air 
quality design objective.
    (iii) Operating system. A system of established procedures for 
determining the need for curtailments and for accomplishing such 
curtailments. Documentation of this system, as required by paragraph 
(n)(4), may consist of a compendium of memoranda or comparable material 
which define the criteria and procedures for curtailments and which 
identify the type and number of personnel authorized to initiate 
curtailments.
    (iv) Meteorologist. A person, schooled in meteorology, capable of 
interpreting data obtained from the meteorological network and qualified 
to forecast meteorological incidents and their effect on ambient air 
quality. Sources may have obtained meteorological services through a 
consultant. Services of such a consultant could include sufficient 
training of source personnel for certain operational procedures, but not 
for design, of the ICS.
    (4) Documentation sufficient to support the claim that the ICS met 
the criteria listed in this paragraph must be provided. Such 
documentation may include affidavits or other documentation.



Sec. 51.120  Requirements for State Implementation Plan revisions relating to new motor vehicles.

    (a) The EPA Administrator finds that the State Implementation Plans 
(SIPs) for the States of Connecticut, Delaware, Maine, Maryland, 
Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode 
Island, and Vermont, the portion of Virginia included (as of November 
15, 1990) within the Consolidated Metropolitan Statistical Area that 
includes the District of Columbia, are substantially inadequate to 
comply with the requirements of section 110(a)(2)(D) of the Clean Air

[[Page 143]]

Act, 42 U.S.C. 7410(a)(2)(D), and to mitigate adequately the interstate 
pollutant transport described in section 184 of the Clean Air Act, 42 
U.S.C. 7511C, to the extent that they do not provide for emission 
reductions from new motor vehicles in the amount that would be achieved 
by the Ozone Transport Commission low emission vehicle (OTC LEV) program 
described in paragraph (c) of this section. This inadequacy will be 
deemed cured for each of the aforementioned States (including the 
District of Columbia) in the event that EPA determines through 
rulemaking that a national LEV-equivalent new motor vehicle emission 
control program is an acceptable alternative for OTC LEV and finds that 
such program is in effect. In the event no such finding is made, each of 
those States must adopt and submit to EPA by February 15, 1996 a SIP 
revision meeting the requirements of paragraph (b) of this section in 
order to cure the SIP inadequacy.
    (b) If a SIP revision is required under paragraph (a) of this 
section, it must contain the OTC LEV program described in paragraph (c) 
of this section unless the State adopts and submits to EPA, as a SIP 
revision, other emission-reduction measures sufficient to meet the 
requirements of paragraph (d) of this section. If a State adopts and 
submits to EPA, as a SIP revision, other emission-reduction measures 
pursuant to paragraph (d) of this section, then for purposes of 
determining whether such a SIP revision is complete within the meaning 
of section 110(k)(1) (and hence is eligible at least for consideration 
to be approved as satisfying paragraph (d) of this section), such a SIP 
revision must contain other adopted emission-reduction measures that, 
together with the identified potentially broadly practicable measures, 
achieve at least the minimum level of emission reductions that could 
potentially satisfy the requirements of paragraph (d) of this section. 
All such measures must be fully adopted and enforceable.
    (c) The OTC LEV program is a program adopted pursuant to section 177 
of the Clean Air Act.
    (1) The OTC LEV program shall contain the following elements:
    (i) It shall apply to all new 1999 and later model year passenger 
cars and light-duty trucks (0-5750 pounds loaded vehicle weight), as 
defined in Title 13, California Code of Regulations, section 1900(b)(11) 
and (b)(8), respectively, that are sold, imported, delivered, purchased, 
leased, rented, acquired, received, or registered in any area of the 
State that is in the Northeast Ozone Transport Region as of December 19, 
1994.
    (ii) All vehicles to which the OTC LEV program is applicable shall 
be required to have a certificate from the California Air Resources 
Board (CARB) affirming compliance with California standards.
    (iii) All vehicles to which this LEV program is applicable shall be 
required to meet the mass emission standards for Non-Methane Organic 
Gases (NMOG), Carbon Monoxide (CO), Oxides of Nitrogen (NOX), 
Formaldehyde (HCHO), and particulate matter (PM) as specified in Title 
13, California Code of Regulations, section 1960.1(f)(2) (and 
formaldehyde standards under section 1960.1(e)(2), as applicable) or as 
specified by California for certification as a TLEV (Transitional Low-
Emission Vehicle), LEV (Low-Emission Vehicle), ULEV (Ultra-Low-Emission 
Vehicle), or ZEV (Zero-Emission Vehicle) under section 1960.1(g)(1) (and 
section 1960.1(e)(3), for formaldehyde standards, as applicable).
    (iv) All manufacturers of vehicles subject to the OTC LEV program 
shall be required to meet the fleet average NMOG exhaust emission values 
for production and delivery for sale of their passenger cars, light-duty 
trucks 0-3750 pounds loaded vehicle weight, and light-duty trucks 3751-
5750 pounds loaded vehicle weight specified in Title 13, California Code 
of Regulations, section 1960.1(g)(2) for each model year beginning in 
1999. A State may determine not to implement the NMOG fleet average in 
the first model year of the program if the State begins implementation 
of the program late in a calendar year. However, all States must 
implement the NMOG fleet average in any full model years of the LEV 
program.
    (v) All manufacturers shall be allowed to average, bank and trade 
credits in the same manner as allowed

[[Page 144]]

under the program specified in Title 13, California Code of Regulations, 
section 1960.1(g)(2) footnote 7 for each model year beginning in 1999. 
States may account for credits banked by manufacturers in California or 
New York in years immediately preceding model year 1999, in a manner 
consistent with California banking and discounting procedures.
    (vi) The provisions for small volume manufacturers and intermediate 
volume manufacturers, as applied by Title 13, California Code of 
Regulations to California's LEV program, shall apply. Those 
manufacturers defined as small volume manufacturers and intermediate 
volume manufacturers in California under California's regulations shall 
be considered small volume manufacturers and intermediate volume 
manufacturers under this program.
    (vii) The provisions for hybrid electric vehicles (HEVs), as defined 
in Title 13 California Code of Regulations, section 1960.1, shall apply 
for purposes of calculating fleet average NMOG values.
    (viii) The provisions for fuel-flexible vehicles and dual-fuel 
vehicles specified in Title 13, California Code of Regulations, section 
1960.1(g)(1) footnote 4 shall apply.
    (ix) The provisions for reactivity adjustment factors, as defined by 
Title 13, California Code of Regulations, shall apply.
    (x) The aforementioned State OTC LEV standards shall be identical to 
the aforementioned California standards as such standards exist on 
December 19, 1994.
    (xi) All States' OTC LEV programs must contain any other provisions 
of California's LEV program specified in Title 13, California Code of 
Regulations necessary to comply with section 177 of the Clean Air Act.
    (2) States are not required to include the mandate for production of 
ZEVs specified in Title 13, California Code of Regulations, section 
1960.1(g)(2) footnote 9.
    (3) Except as specified elsewhere in this section, States may 
implement the OTC LEV program in any manner consistent with the Act that 
does not decrease the emissions reductions or jeopardize the 
effectiveness of the program.
    (d) The SIP revision that paragraph (b) of this section describes as 
an alternative to the OTC LEV program described in paragraph (c) of this 
section must contain a set of State-adopted measures that provides at 
least the following amount of emission reductions in time to bring 
serious ozone nonattainment areas into attainment by their 1999 
attainment date:
    (1) Reductions at least equal to the difference between:
    (i) The nitrogen oxides (NOX) emission reductions from 
the 1990 statewide emissions inventory achievable through implementation 
of all of the Clean Air Act-mandated and potentially broadly practicable 
control measures throughout all portions of the State that are within 
the Northeast Ozone Transport Region created under section 184(a) of the 
Clean Air Act as of December 19, 1994; and
    (ii) A reduction in NOX emissions from the 1990 statewide 
inventory in such portions of the State of 50% or whatever greater 
reduction is necessary to prevent significant contribution to 
nonattainment in, or interference with maintenance by, any downwind 
State.
    (2) Reductions at least equal to the difference between:
    (i) The VOC emission reductions from the 1990 statewide emissions 
inventory achievable through implementation of all of the Clean Air Act-
mandated and potentially broadly practicable control measures in all 
portions of the State in, or near and upwind of, any of the serious or 
severe ozone nonattainment areas lying in the series of such areas 
running northeast from the Washington, DC, ozone nonattainment area to 
and including the Portsmouth, New Hampshire ozone nonattainment area; 
and
    (ii) A reduction in VOC emissions from the 1990 emissions inventory 
in all such areas of 50% or whatever greater reduction is necessary to 
prevent significant contribution to nonattainment in, or interference 
with maintenance by, any downwind State.

[60 FR 4736, Jan. 24, 1995]

[[Page 145]]



Sec. 51.121  Findings and requirements for submission of State implementation plan revisions relating to emissions of oxides of nitrogen.

    (a)(1) The Administrator finds that the State implementation plan 
(SIP) for each jurisdiction listed in paragraph (c) of this section is 
substantially inadequate to comply with the requirements of section 
110(a)(2)(D)(i)(I) of the Clean Air Act (CAA), 42 U.S.C. 
7410(a)(2)(D)(i)(I), because the SIP does not include adequate 
provisions to prohibit sources and other activities from emitting 
nitrogen oxides (``NOX'') in amounts that will contribute 
significantly to nonattainment in one or more other States with respect 
to the 1-hour ozone national ambient air quality standards (NAAQS). Each 
of the jurisdictions listed in paragraph (c) of this section must submit 
to EPA a SIP revision that cures the inadequacy.
    (2) Under section 110(a)(1) of the CAA, 42 U.S.C. 7410(a)(1), the 
Administrator determines that each jurisdiction listed in paragraph (c) 
of this section must submit a SIP revision to comply with the 
requirements of section 110(a)(2)(D)(i)(I), 42 U.S.C. 
7410(a)(2)(D)(i)(I), through the adoption of adequate provisions 
prohibiting sources and other activities from emitting NOX in 
amounts that will contribute significantly to nonattainment in, or 
interfere with maintenance by, one or more other States with respect to 
the 8-hour ozone NAAQS.
    (b)(1) For each jurisdiction listed in paragraph (c) of this 
section, the SIP revision required under paragraph (a) of this section 
will contain adequate provisions, for purposes of complying with section 
110(a)(2)(D)(i)(I) of the CAA, 42 U.S.C. 7410(a)(2)(D)(i)(I), only if 
the SIP revision:
    (i) Contains control measures adequate to prohibit emissions of 
NOX that would otherwise be projected, in accordance with 
paragraph (g) of this section, to cause the jurisdiction's overall 
NOX emissions to be in excess of the budget for that 
jurisdiction described in paragraph (e) of this section (except as 
provided in paragraph (b)(2) of this section),
    (ii) Requires full implementation of all such control measures by no 
later than May 1, 2003, and
    (iii) Meets the other requirements of this section. The SIP 
revision's compliance with the requirement of paragraph (b)(1)(i) of 
this section shall be considered compliance with the jurisdiction's 
budget for purposes of this section.
    (2) The requirements of paragraph (b)(1)(i) of this section shall be 
deemed satisfied, for the portion of the budget covered by an interstate 
trading program, if the SIP revision:
    (i) Contains provisions for an interstate trading program that EPA 
determines will, in conjunction with interstate trading programs for one 
or more other jurisdictions, prohibit NOX emissions in excess 
of the sum of the portion of the budgets covered by the trading programs 
for those jurisdictions; and
    (ii) Conforms to the following criteria:
    (A) Emissions reductions used to demonstrate compliance with the 
revision must occur during the ozone season.
    (B) Emissions reductions occurring prior to the year 2003 may be 
used by a source to demonstrate compliance with the SIP revision for the 
2003 and 2004 ozone seasons, provided the SIP's provisions regarding 
such use comply with the requirements of paragraph (e)(3) of this 
section.
    (C) Emissions reduction credits or emissions allowances held by a 
source or other person following the 2003 ozone season or any ozone 
season thereafter that are not required to demonstrate compliance with 
the SIP for the relevant ozone season may be banked and used to 
demonstrate compliance with the SIP in a subsequent ozone season.
    (D) Early reductions created according to the provisions in 
paragraph (b)(2)(ii)(B) of this section and used in the 2003 ozone 
season are not subject to the flow control provisions set forth in 
paragraph (b)(2)(ii)(E) of this section.
    (E) Starting with the 2004 ozone season, the SIP shall include 
provisions to limit the use of banked emissions reduction credits or 
emissions allowances

[[Page 146]]

beyond a predetermined amount as calculated by one of the following 
approaches:
    (1) Following the determination of compliance after each ozone 
season, if the total number of emissions reduction credits or banked 
allowances held by sources or other persons subject to the trading 
program exceeds 10 percent of the sum of the allowable ozone season 
NOX emissions for all sources subject to the trading program, 
then all banked allowances used for compliance for the following ozone 
season shall be subject to the following:
    (i) A ratio will be established according to the following formula: 
(0.10)  x  (the sum of the allowable ozone season NOX 
emissions for all sources subject to the trading program)  (the 
total number of banked emissions reduction credits or emissions 
allowances held by all sources or other persons subject to the trading 
program).
    (ii) The ratio, determined using the formula specified in paragraph 
(b)(2)(ii)(E)(1)(i) of this section, will be multiplied by the number of 
banked emissions reduction credits or emissions allowances held in each 
account at the time of compliance determination. The resulting product 
is the number of banked emissions reduction credits or emissions 
allowances in the account which can be used in the current year's ozone 
season at a rate of 1 credit or allowance for every 1 ton of emissions. 
The SIP shall specify that banked emissions reduction credits or 
emissions allowances in excess of the resulting product either may not 
be used for compliance, or may only be used for compliance at a rate no 
less than 2 credits or allowances for every 1 ton of emissions.
    (2) At the time of compliance determination for each ozone season, 
if the total number of banked emissions reduction credits or emissions 
allowances held by a source subject to the trading program exceeds 10 
percent of the source's allowable ozone season NOX emissions, 
all banked emissions reduction credits or emissions allowances used for 
compliance in such ozone season by the source shall be subject to the 
following:
    (i) The source may use an amount of banked emissions reduction 
credits or emissions allowances not greater than 10 percent of the 
source's allowable ozone season NOX emissions for compliance 
at a rate of 1 credit or allowance for every 1 ton of emissions.
    (ii) The SIP shall specify that banked emissions reduction credits 
or emissions allowances in excess of 10 percent of the source's 
allowable ozone season NOX emissions may not be used for 
compliance, or may only be used for compliance at a rate no less than 2 
credits or allowances for every 1 ton of emissions.
    (c) The following jurisdictions (hereinafter referred to as 
``States'') are subject to the requirements of this section: Alabama, 
Connecticut, Delaware, Georgia, Illinois, Indiana, Kentucky, Maryland, 
Massachusetts, Michigan, Missouri, New Jersey, New York, North Carolina, 
Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Virginia, 
West Virginia, Wisconsin, and the District of Columbia.
    (d)(1) The SIP submissions required under paragraph (a) of this 
section must be submitted to EPA by no later than September 30, 1999.
    (2) The State makes an official submission of its SIP revision to 
EPA only when:
    (i) The submission conforms to the requirements of appendix V to 
this part; and
    (ii) The State delivers five copies of the plan to the appropriate 
Regional Office, with a letter giving notice of such action.
    (e)(1) The NOX budget for a State listed in paragraph (c) 
of this section is defined as the total amount of NOX 
emissions from all sources in that State, as indicated in paragraph 
(e)(2) of this section with respect to that State, which the State must 
demonstrate that it will not exceed in the 2007 ozone season pursuant to 
paragraph (g)(1) of this section.
    (2) The State-by-State amounts of the NOX budget, 
expressed in tons per ozone season, are as follows:

------------------------------------------------------------------------
                           State                                Budget
------------------------------------------------------------------------
Alabama....................................................      172,619
Connecticut................................................       42,849
Delaware...................................................       22,861
District of Columbia.......................................        6,658
Georgia....................................................      188,572
Illinois...................................................      270,560
Indiana....................................................      229,965

[[Page 147]]

 
Kentucky...................................................      162,272
Maryland...................................................       81,898
Massachusetts..............................................       84,848
Michigan...................................................      229,702
Missouri...................................................      125,603
New Jersey.................................................       96,876
New York...................................................      240,288
North Carolina.............................................      165,022
Ohio.......................................................      249,274
Pennsylvania...............................................      257,592
Rhode Island...............................................        9,378
South Carolina.............................................      123,105
Tennessee..................................................      198,045
Virginia...................................................      180,195
West Virginia..............................................       83,833
Wisconsin..................................................      135,771
                                                            ------------
    Total..................................................    3,357,786
------------------------------------------------------------------------

    (3)(i) Notwithstanding the State's obligation to comply with the 
budgets set forth in paragraph (e)(2) of this section, a SIP revision 
may allow sources required by the revision to implement NOX 
emission control measures by May 1, 2003 to demonstrate compliance in 
the 2003 and 2004 ozone seasons using credit issued from the State's 
compliance supplement pool, as set forth in paragraph (e)(3)(iii) of 
this section.
    (ii) A source may not use credit from the compliance supplement pool 
to demonstrate compliance after the 2004 ozone season.
    (iii) The State-by-State amounts of the compliance supplement pool 
are as follows:

------------------------------------------------------------------------
                                                              Compliance
                                                              supplement
                           State                              pool (tons
                                                               of NOX)
------------------------------------------------------------------------
Alabama....................................................       11,687
Connecticut................................................          569
Delaware...................................................          168
District of Columbia.......................................            0
Georgia....................................................       11,440
Illinois...................................................       17,688
Indiana....................................................       19,915
Kentucky...................................................       13,520
Maryland...................................................        3,882
Massachusetts..............................................          404
Michigan...................................................       11,356
Missouri...................................................       11,199
New Jersey.................................................        1,550
New York...................................................        2,764
North Carolina.............................................       10,737
Ohio.......................................................       22,301
Pennsylvania...............................................       15,763
Rhode Island...............................................           15
South Carolina.............................................        5,344
Tennessee..................................................       10,565
Virginia...................................................        5,504
West Virginia..............................................       16,709
Wisconsin..................................................        6,920
                                                            ------------
    Total..................................................      200,000
------------------------------------------------------------------------

    (iv) The SIP revision may provide for the distribution of the 
compliance supplement pool to sources that are required to implement 
control measures using one or both of the following two mechanisms:
    (A) The State may issue some or all of the compliance supplement 
pool to sources that implement emissions reductions during the ozone 
season beyond all applicable requirements in years prior to the year 
2003 according to the following provisions:
    (1) The State shall complete the issuance process by no later than 
May 1, 2003.
    (2) The emissions reduction may not be required by the State's SIP 
or be otherwise required by the CAA.
    (3) The emissions reduction must be verified by the source as 
actually having occurred during an ozone season between September 30, 
1999 and May 1, 2003.
    (4) The emissions reduction must be quantified according to 
procedures set forth in the SIP revision and approved by EPA. Emissions 
reductions implemented by sources serving electric generators with a 
nameplate capacity greater than 25 MWe, or boilers, combustion turbines 
or combined cycle units with a maximum design heat input greater than 
250 mmBtu/hr, must be quantified according to the requirements in 
paragraph (i)(4) of this section.
    (5) If the SIP revision contains approved provisions for an 
emissions trading program, sources that receive credit according to the 
requirements of this paragraph may trade the credit to other sources or 
persons according to the provisions in the trading program.
    (B) The State may issue some or all of the compliance supplement 
pool to sources that demonstrate a need for an extension of the May 1, 
2003 compliance deadline according to the following provisions:
    (1) The State shall initiate the issuance process by the later date 
of September 30, 2002 or after the State issues credit according to the 
procedures in paragraph (e)(3)(iv)(A) of this section.
    (2) The State shall complete the issuance process by no later than 
May 1, 2003.

[[Page 148]]

    (3) The State shall issue credit to a source only if the source 
demonstrates the following:
    (i) For a source used to generate electricity, compliance with the 
SIP revision's applicable control measures by May 1, 2003, would create 
undue risk for the reliability of the electricity supply. This 
demonstration must include a showing that it would not be feasible to 
import electricity from other electricity generation systems during the 
installation of control technologies necessary to comply with the SIP 
revision.
    (ii) For a source not used to generate electricity, compliance with 
the SIP revision's applicable control measures by May 1, 2003, would 
create undue risk for the source or its associated industry to a degree 
that is comparable to the risk described in paragraph 
(e)(3)(iv)(B)(3)(i) of this section.
    (iii) For a source subject to an approved SIP revision that allows 
for early reduction credits in accordance with paragraph (e)(3)(iv)(A) 
of this section, it was not possible for the source to comply with 
applicable control measures by generating early reduction credits or 
acquiring early reduction credits from other sources.
    (iv) For a source subject to an approved emissions trading program, 
it was not possible to comply with applicable control measures by 
acquiring sufficient credit from other sources or persons subject to the 
emissions trading program.
    (4) The State shall ensure the public an opportunity, through a 
public hearing process, to comment on the appropriateness of allocating 
compliance supplement pool credits to a source under paragraph 
(e)(3)(iv)(B) of this section.
    (4) If, no later than February 22, 1999, any member of the public 
requests revisions to the source-specific data and vehicle miles 
traveled (VMT) and nonroad mobile growth rates, VMT distribution by 
vehicle class, average speed by roadway type, inspection and maintenance 
program parameters, and other input parameters used to establish the 
State budgets set forth in paragraph (e)(2) of this section or the 2007 
baseline sub-inventory information set forth in paragraph (g)(2)(ii) of 
this section, then EPA will act on that request no later than April 23, 
1999 provided:
    (i) The request is submitted in electronic format;
    (ii) Information is provided to corroborate and justify the need for 
the requested modification;
    (iii) The request includes the following data information regarding 
any electricity-generating source at issue:
    (A) Federal Information Placement System (FIPS) State Code;
    (B) FIPS County Code;
    (C) Plant name;
    (D) Plant ID numbers (ORIS code preferred, State agency tracking 
number also or otherwise);
    (E) Unit ID numbers (a unit is a boiler or other combustion device);
    (F) Unit type;
    (G) Primary fuel on a heat input basis;
    (H) Maximum rated heat input capacity of unit;
    (I) Nameplate capacity of the largest generator the unit serves;
    (J) Ozone season heat inputs for the years 1995 and 1996;
    (K) 1996 (or most recent) average NOX rate for the ozone 
season;
    (L) Latitude and longitude coordinates;
    (M) Stack parameter information ;
    (N) Operating parameter information;
    (O) Identification of specific change to the inventory; and
    (P) Reason for the change;
    (iv) The request includes the following data information regarding 
any non-electricity generating point source at issue:
    (A) FIPS State Code;
    (B) FIPS County Code;
    (C) Plant name;
    (D) Facility primary standard industrial classification code (SIC);
    (E) Plant ID numbers (NEDS, AIRS/AFS, and State agency tracking 
number also or otherwise);
    (F) Unit ID numbers (a unit is a boiler or other combustion device);
    (G) Primary source classification code (SCC);
    (H) Maximum rated heat input capacity of unit;
    (I) 1995 ozone season or typical ozone season daily NOX 
emissions;

[[Page 149]]

    (J) 1995 existing NOX control efficiency;
    (K) Latitude and longitude coordinates;
    (L) Stack parameter information;
    (M) Operating parameter information;
    (N) Identification of specific change to the inventory; and
    (O) Reason for the change;
    (v) The request includes the following data information regarding 
any stationary area source or nonroad mobile source at issue:
    (A) FIPS State Code;
    (B) FIPS County Code;
    (C) Primary source classification code (SCC);
    (D) 1995 ozone season or typical ozone season daily NOX 
emissions;
    (E) 1995 existing NOX control efficiency;
    (F) Identification of specific change to the inventory; and
    (G) Reason for the change;
    (vi) The request includes the following data information regarding 
any highway mobile source at issue:
    (A) FIPS State Code;
    (B) FIPS County Code;
    (C) Primary source classification code (SCC) or vehicle type;
    (D) 1995 ozone season or typical ozone season daily vehicle miles 
traveled (VMT);
    (E) 1995 existing NOX control programs;
    (F) identification of specific change to the inventory; and
    (G) reason for the change.
    (f) Each SIP revision must set forth control measures to meet the 
NOX budget in accordance with paragraph (b)(1)(i) of this 
section, which include the following:
    (1) A description of enforcement methods including, but not limited 
to:
    (i) Procedures for monitoring compliance with each of the selected 
control measures;
    (ii) Procedures for handling violations; and
    (iii) A designation of agency responsibility for enforcement of 
implementation.
    (2) Should a State elect to impose control measures on fossil fuel-
fired NOX sources serving electric generators with a 
nameplate capacity greater than 25 MWe or boilers, combustion turbines 
or combined cycle units with a maximum design heat input greater than 
250 mmBtu/hr as a means of meeting its NOX budget, then those 
measures must:
    (i)(A) Impose a NOX mass emissions cap on each source;
    (B) Impose a NOX emissions rate limit on each source and 
assume maximum operating capacity for every such source for purposes of 
estimating mass NOX emissions; or
    (C) Impose any other regulatory requirement which the State has 
demonstrated to EPA provides equivalent or greater assurance than 
options in paragraphs (f)(2)(i)(A) or (f)(2)(i)(B) of this section that 
the State will comply with its NOX budget in the 2007 ozone 
season; and
    (ii) Impose enforceable mechanisms, in accordance with paragraphs 
(b)(1) (i) and (ii) of this section, to assure that collectively all 
such sources, including new or modified units, will not exceed in the 
2007 ozone season the total NOX emissions projected for such 
sources by the State pursuant to paragraph (g) of this section.
    (3) For purposes of paragraph (f)(2) of this section, the term 
``fossil fuel-fired'' means, with regard to a NOX source:
    (i) The combustion of fossil fuel, alone or in combination with any 
other fuel, where fossil fuel actually combusted comprises more than 50 
percent of the annual heat input on a Btu basis during any year starting 
in 1995 or, if a NOX source had no heat input starting in 
1995, during the last year of operation of the NOX source 
prior to 1995; or
    (ii) The combustion of fossil fuel, alone or in combination with any 
other fuel, where fossil fuel is projected to comprise more than 50 
percent of the annual heat input on a Btu basis during any year; 
provided that the NOX source shall be ``fossil fuel-fired'' 
as of the date, during such year, on which the NOX source 
begins combusting fossil fuel.
    (g)(1) Each SIP revision must demonstrate that the control measures 
contained in it are adequate to provide for the timely compliance with 
the State's NOX budget during the 2007 ozone season.

[[Page 150]]

    (2) The demonstration must include the following:
    (i) Each revision must contain a detailed baseline inventory of 
NOX mass emissions from the following sources in the year 
2007, absent the control measures specified in the SIP submission: 
electric generating units (EGU), non-electric generating units (non-
EGU), area, nonroad and highway sources. The State must use the same 
baseline emissions inventory that EPA used in calculating the State's 
NOX budget, as set forth for the State in paragraph 
(g)(2)(ii) of this section, except that EPA may direct the State to use 
different baseline inventory information if the State fails to certify 
that it has implemented all of the control measures assumed in 
developing the baseline inventory.
    (ii) The revised NOX emissions sub-inventories for each 
State, expressed in tons per ozone season, are as follows:

----------------------------------------------------------------------------------------------------------------
                     State                          EGU      Non-EGU    Area     Nonroad    Highway      Total
----------------------------------------------------------------------------------------------------------------
Alabama.......................................      29,022    43,415    28,762    20,146      51,274     172,619
Connecticut...................................       2,652     5,216     4,821    10,736      19,424      42,849
Delaware......................................       5,250     2,473     1,129     5,651       8,358      22,861
District of Columbia..........................         207       282       830     3,135       2,204       6,658
Georgia.......................................      30,402    29,716    13,212    26,467      88,775     188,572
Illinois......................................      32,372    59,577     9,369    56,724     112,518     270,560
Indiana.......................................      47,731    47,363    29,070    26,494      79,307     229,965
Kentucky......................................      36,503    25,669    31,807    15,025      53,268     162,272
Maryland......................................      14,656    12,585     4,448    20,026      30,183      81,898
Massachusetts.................................      15,146    10,298    11,048    20,166      28,190      84,848
Michigan......................................      32,228    60,055    31,721    26,935      78,763     229,702
Missouri......................................      24,216    21,602     7,341    20,829      51,615     125,603
New Jersey....................................      10,250    15,464    12,431    23,565      35,166      96,876
New York......................................      31,036    25,477    17,423    42,091     124,261     240,288
North Carolina................................      31,821    26,434    11,067    22,005      73,695     165,022
Ohio..........................................      48,990    40,194    21,860    43,380      94,850     249,274
Pennsylvania..................................      47,469    70,132    17,842    30,571      91,578     257,592
Rhode Island..................................         997     1,635       448     2,455       3,843       9,378
South Carolina................................      16,772    27,787     9,415    14,637      54,494     123,105
Tennessee.....................................      25,814    39,636    13,333    52,920      66,342     198,045
Virginia......................................      17,187    35,216    27,738    27,859      72,195     180,195
West Virginia.................................      26,859    20,238     5,459    10,433      20,844      83,833
Wisconsin.....................................      17,381    19,853    11,253    17,965      69,319     135,771
                                               -----------------------------------------------------------------
    Total.....................................     544,961   640,317   321,827   540,215   1,310,466  3,357,786
----------------------------------------------------------------------------------------------------------------
Note to paragraph (g)(2)(ii): Totals may not sum due to rounding.

    (iii) Each revision must contain a summary of NOX mass 
emissions in 2007 projected to result from implementation of each of the 
control measures specified in the SIP submission and from all 
NOX sources together following implementation of all such 
control measures, compared to the baseline 2007 NOX emissions 
inventory for the State described in paragraph (g)(2)(i) of this 
section. The State must provide EPA with a summary of the computations, 
assumptions, and judgments used to determine the degree of reduction in 
projected 2007 NOX emissions that will be achieved from the 
implementation of the new control measures compared to the baseline 
emissions inventory.
    (iv) Each revision must identify the sources of the data used in the 
projection of emissions.
    (h) Each revision must comply with Sec. 51.116 of this part 
(regarding data availability).
    (i) Each revision must provide for monitoring the status of 
compliance with any control measures adopted to meet the NOX 
budget. Specifically, the revision must meet the following requirements:
    (1) The revision must provide for legally enforceable procedures for 
requiring owners or operators of stationary sources to maintain records 
of and periodically report to the State:
    (i) Information on the amount of NOX emissions from the 
stationary sources; and

[[Page 151]]

    (ii) Other information as may be necessary to enable the State to 
determine whether the sources are in compliance with applicable portions 
of the control measures;
    (2) The revision must comply with Sec. 51.212 of this part 
(regarding testing, inspection, enforcement, and complaints);
    (3) If the revision contains any transportation control measures, 
then the revision must comply with Sec. 51.213 of this part (regarding 
transportation control measures);
    (4) If the revision contains measures to control fossil fuel-fired 
NOX sources serving electric generators with a nameplate 
capacity greater than 25 MWe or boilers, combustion turbines or combined 
cycle units with a maximum design heat input greater than 250 mmBtu/hr, 
then the revision must require such sources to comply with the 
monitoring provisions of part 75, subpart H.
    (5) For purposes of paragraph (i)(4) of this section, the term 
``fossil fuel-fired'' means, with regard to a NOX source:
    (i) The combustion of fossil fuel, alone or in combination with any 
other fuel, where fossil fuel actually combusted comprises more than 50 
percent of the annual heat input on a Btu basis during any year starting 
in 1995 or, if a NOX source had no heat input starting in 
1995, during the last year of operation of the NOX source 
prior to 1995; or
    (ii) The combustion of fossil fuel, alone or in combination with any 
other fuel, where fossil fuel is projected to comprise more than 50 
percent of the annual heat input on a Btu basis during any year, 
provided that the NOX source shall be ``fossil fuel-fired'' 
as of the date, during such year, on which the NOX source 
begins combusting fossil fuel.
    (j) Each revision must show that the State has legal authority to 
carry out the revision, including authority to:
    (1) Adopt emissions standards and limitations and any other measures 
necessary for attainment and maintenance of the State's NOX 
budget specified in paragraph (e) of this section;
    (2) Enforce applicable laws, regulations, and standards, and seek 
injunctive relief;
    (3) Obtain information necessary to determine whether air pollution 
sources are in compliance with applicable laws, regulations, and 
standards, including authority to require recordkeeping and to make 
inspections and conduct tests of air pollution sources;
    (4) Require owners or operators of stationary sources to install, 
maintain, and use emissions monitoring devices and to make periodic 
reports to the State on the nature and amounts of emissions from such 
stationary sources; also authority for the State to make such data 
available to the public as reported and as correlated with any 
applicable emissions standards or limitations.
    (k)(1) The provisions of law or regulation which the State 
determines provide the authorities required under this section must be 
specifically identified, and copies of such laws or regulations must be 
submitted with the SIP revision.
    (2) Legal authority adequate to fulfill the requirements of 
paragraphs (j)(3) and (4) of this section may be delegated to the State 
under section 114 of the CAA.
    (l)(1) A revision may assign legal authority to local agencies in 
accordance with Sec. 51.232 of this part.
    (2) Each revision must comply with Sec. 51.240 of this part 
(regarding general plan requirements).
    (m) Each revision must comply with Sec. 51.280 of this part 
(regarding resources).
    (n) For purposes of the SIP revisions required by this section, EPA 
may make a finding as applicable under section 179(a)(1)-(4) of the CAA, 
42 U.S.C. 7509(a)(1)-(4), starting the sanctions process set forth in 
section 179(a) of the CAA. Any such finding will be deemed a finding 
under Sec. 52.31(c) of this part and sanctions will be imposed in 
accordance with the order of sanctions and the terms for such sanctions 
established in Sec. 52.31 of this part.
    (o) Each revision must provide for State compliance with the 
reporting requirements set forth in Sec. 51.122 of this part.
    (p)(1) Notwithstanding any other provision of this section, if a 
State adopts regulations substantively identical to 40 CFR part 96 (the 
model NOX budget

[[Page 152]]

trading program for SIPs), incorporates such part by reference into its 
regulations, or adopts regulations that differ substantively from such 
part only as set forth in paragraph (p)(2) of this section, then that 
portion of the State's SIP revision is automatically approved as 
satisfying the same portion of the State's NOX emission 
reduction obligations as the State projects such regulations will 
satisfy, provided that:
    (i) The State has the legal authority to take such action and to 
implement its responsibilities under such regulations, and
    (ii) The SIP revision accurately reflects the NOX 
emissions reductions to be expected from the State's implementation of 
such regulations.
    (2) If a State adopts an emissions trading program that differs 
substantively from 40 CFR part 96 in only the following respects, then 
such portion of the State's SIP revision is approved as set forth in 
paragraph (p)(1) of this section:
    (i) The State may expand the applicability provisions of the trading 
program to include units (as defined in 40 CFR 96.2) that are smaller 
than the size criteria thresholds set forth in 40 CFR 96.4(a);
    (ii) The State may decline to adopt the exemption provisions set 
forth in 40 CFR 96.4(b);
    (iii) The State may decline to adopt the opt-in provisions set forth 
in subpart I of 40 CFR part 96;
    (iv) The State may decline to adopt the allocation provisions set 
forth in subpart E of 40 CFR part 96 and may instead adopt any 
methodology for allocating NOX allowances to individual 
sources, provided that:
    (A) The State's methodology does not allow the State to allocate 
NOX allowances in excess of the total amount of 
NOX emissions which the State has assigned to its trading 
program; and
    (B) The State's methodology conforms with the timing requirements 
for submission of allocations to the Administrator set forth in 40 CFR 
96.41; and
    (v) The State may decline to adopt the early reduction credit 
provisions set forth in 40 CFR 96.55(c) and may instead adopt any 
methodology for issuing credit from the State's compliance supplement 
pool that complies with paragraph (e)(3) of this section.
    (3) If a State adopts an emissions trading program that differs 
substantively from 40 CFR part 96 other than as set forth in paragraph 
(p)(2) of this section, then such portion of the State's SIP revision is 
not automatically approved as set forth in paragraph (p)(1) of this 
section but will be reviewed by the Administrator for approvability in 
accordance with the other provisions of this section.

[63 FR 57491, Oct. 27, 1998, as amended at 63 FR 71225, Dec. 24, 1998; 
64 FR 26305, May 14, 1999; 65 FR 11230, Mar. 2, 2000]



Sec. 51.122  Emissions reporting requirements for SIP revisions relating to budgets for NOX emissions.

    (a) For its transport SIP revision under Sec. 51.121 of this part, 
each State must submit to EPA NOX emissions data as described 
in this section.
    (b) Each revision must provide for periodic reporting by the State 
of NOX emissions data to demonstrate whether the State's 
emissions are consistent with the projections contained in its approved 
SIP submission.
    (1) Annual reporting. Each revision must provide for annual 
reporting of NOX emissions data as follows:
    (i) The State must report to EPA emissions data from all 
NOX sources within the State for which the State specified 
control measures in its SIP submission under Sec. 51.121(g) of this 
part. This would include all sources for which the State has adopted 
measures that differ from the measures incorporated into the baseline 
inventory for the year 2007 that the State developed in accordance with 
Sec. 51.121(g) of this part.
    (ii) If sources report NOX emissions data to EPA annually 
pursuant to a trading program approved under Sec. 51.121(p) of this part 
or pursuant to the monitoring and reporting requirements of subpart H of 
40 CFR part 75, then the State need not provide annual reporting to EPA 
for such sources.
    (2) Triennial reporting. Each plan must provide for triennial (i.e., 
every third year) reporting of NOX emissions data from all 
sources within the State.

[[Page 153]]

    (3) Year 2007 reporting. Each plan must provide for reporting of 
year 2007 NOX emissions data from all sources within the 
State.
    (4) The data availability requirements in Sec. 51.116 of this part 
must be followed for all data submitted to meet the requirements of 
paragraphs (b)(1),(2) and (3) of this section.
    (c) The data reported in paragraph (b) of this section for 
stationary point sources must meet the following minimum criteria:
    (1) For annual data reporting purposes the data must include the 
following minimum elements:
    (i) Inventory year.
    (ii) State Federal Information Placement System code.
    (iii) County Federal Information Placement System code.
    (iv) Federal ID code (plant).
    (v) Federal ID code (point).
    (vi) Federal ID code (process).
    (vii) Federal ID code (stack).
    (vii) Site name.
    (viii) Physical address.
    (ix) SCC.
    (x) Pollutant code.
    (xi) Ozone season emissions.
    (xii) Area designation.
    (2) In addition, the annual data must include the following minimum 
elements as applicable to the emissions estimation methodology.
    (i) Fuel heat content (annual).
    (ii) Fuel heat content (seasonal).
    (iii) Source of fuel heat content data.
    (iv) Activity throughput (annual).
    (v) Activity throughput (seasonal).
    (vi) Source of activity/throughput data.
    (vii) Spring throughput (%).
    (viii) Summer throughput (%).
    (ix) Fall throughput (%).
    (x) Work weekday emissions.
    (xi) Emission factor.
    (xii) Source of emission factor.
    (xiii) Hour/day in operation.
    (xiv) Operations Start time (hour).
    (xv) Day/week in operation.
    (xvi) Week/year in operation.
    (3) The triennial and 2007 inventories must include the following 
data elements:
    (i) The data required in paragraphs (c)(1) and (c)(2) of this 
section.
    (ii) X coordinate (latitude).
    (iii) Y coordinate (longitude).
    (iv) Stack height.
    (v) Stack diameter.
    (vi) Exit gas temperature.
    (vii) Exit gas velocity.
    (viii) Exit gas flow rate.
    (ix) SIC.
    (x) Boiler/process throughput design capacity.
    (xi) Maximum design rate.
    (xii) Maximum capacity.
    (xiii) Primary control efficiency.
    (xiv) Secondary control efficiency.
    (xv) Control device type.
    (d) The data reported in paragraph (b) of this section for area 
sources must include the following minimum elements:
    (1) For annual inventories it must include:
    (i) Inventory year.
    (ii) State FIPS code.
    (iii) County FIPS code.
    (iv) SCC.
    (v) Emission factor.
    (vi) Source of emission factor.
    (vii) Activity/throughput level (annual).
    (viii) Activity throughput level (seasonal).
    (ix) Source of activity/throughput data.
    (x) Spring throughput (%).
    (xi) Summer throughput (%).
    (xii) Fall throughput (%).
    (xiii) Control efficiency (%).
    (xiv) Pollutant code.
    (xv) Ozone season emissions.
    (xvi) Source of emissions data.
    (xvii) Hour/day in operation.
    (xviii) Day/week in operation.
    (xix) Week/year in operations.
    (2) The triennial and 2007 inventories must contain, at a minimum, 
all the data required in paragraph (d)(1) of this section.
    (e) The data reported in paragraph (b) of this section for mobile 
sources must meet the following minimum criteria:
    (1) For the annual, triennial, and 2007 inventory purposes, the 
following data must be reported:
    (i) Inventory year.
    (ii) State FIPS code.
    (iii) County FIPS code.
    (iv) SCC.
    (v) Emission factor.
    (vi) Source of emission factor.
    (vii) Activity (this must be reported for both highway and nonroad 
activity.

[[Page 154]]

Submit nonroad activity in the form of hours of activity at standard 
load (either full load or average load) for each engine type, 
application, and horsepower range. Submit highway activity in the form 
of vehicle miles traveled (VMT) by vehicle class on each roadway type. 
Report both highway and nonroad activity for a typical ozone season 
weekday day, if the State uses EPA's default weekday/weekend activity 
ratio. If the State uses a different weekday/weekend activity ratio, 
submit separate activity level information for weekday days and weekend 
days).
    (viii) Source of activity data.
    (ix) Pollutant code.
    (x) Summer work weekday emissions.
    (xi) Ozone season emissions.
    (xii) Source of emissions data.
    (2) [Reserved]
    (f) Approval of ozone season calculation by EPA. Each State must 
submit for EPA approval an example of the calculation procedure used to 
calculate ozone season emissions along with sufficient information for 
EPA to verify the calculated value of ozone season emissions.
    (g) Reporting schedules. (1) Annual reports are to begin with data 
for emissions occurring in the year 2003.
    (2) Triennial reports are to begin with data for emissions occurring 
in the year 2002.
    (3) Year 2007 data are to be submitted for emissions occurring in 
the year 2007.
    (4) States must submit data for a required year no later than 12 
months after the end of the calendar year for which the data are 
collected.
    (h) Data reporting procedures. When submitting a formal 
NOX budget emissions report and associated data, States shall 
notify the appropriate EPA Regional Office.
    (1) States are required to report emissions data in an electronic 
format to one of the locations listed in this paragraph (h). Several 
options are available for data reporting.
    (2) An agency may choose to continue reporting to the EPA Aerometric 
Information Retrieval System (AIRS) system using the AIRS facility 
subsystem (AFS) format for point sources. (This option will continue for 
point sources for some period of time after AIRS is reengineered (before 
2002), at which time this choice may be discontinued or modified.)
    (3) An agency may convert its emissions data into the Emission 
Inventory Improvement Program/Electronic Data Interchange (EIIP/EDI) 
format. This file can then be made available to any requestor, either 
using E-mail, floppy disk, or value added network (VAN), or can be 
placed on a file transfer protocol (FTP) site.
    (4) An agency may submit its emissions data in a proprietary format 
based on the EIIP data model.
    (5) For options in paragraphs (h)(3) and (4) of this section, the 
terms submitting and reporting data are defined as either providing the 
data in the EIIP/EDI format or the EIIP based data model proprietary 
format to EPA, Office of Air Quality Planning and Standards, Emission 
Factors and Inventory Group, directly or notifying this group that the 
data are available in the specified format and at a specific electronic 
location (e.g., FTP site).
    (6) For annual reporting (not for triennial reports), a State may 
have sources submit the data directly to EPA to the extent the sources 
are subject to a trading program that qualifies for approval under 
Sec. 51.121(q) of this part, and the State has agreed to accept data in 
this format. The EPA will make both the raw data submitted in this 
format and summary data available to any State that chooses this option.
    (i) Definitions. As used in this section, the following words and 
terms shall have the meanings set forth below:
    (1) Annual emissions. Actual emissions for a plant, point, or 
process, either measured or calculated.
    (2) Ash content. Inert residual portion of a fuel.
    (3) Area designation. The designation of the area in which the 
reporting source is located with regard to the ozone NAAQS. This would 
include attainment or nonattainment designations. For nonattainment 
designations, the classification of the nonattainment area must be 
specified, i.e., transitional, marginal, moderate, serious, severe, or 
extreme.

[[Page 155]]

    (4) Boiler design capacity. A measure of the size of a boiler, based 
on the reported maximum continuous steam flow. Capacity is calculated in 
units of MMBtu/hr.
    (5) Control device type. The name of the type of control device 
(e.g., wet scrubber, flaring, or process change).
    (6) Control efficiency. The emissions reduction efficiency of a 
primary control device, which shows the amount of reductions of a 
particular pollutant from a process' emissions due to controls or 
material change. Control efficiency is usually expressed as a percentage 
or in tenths.
    (7) Day/week in operations. Days per week that the emitting process 
operates.
    (8) Emission factor. Ratio relating emissions of a specific 
pollutant to an activity or material throughput level.
    (9) Exit gas flow rate. Numeric value of stack gas flow rate.
    (10) Exit gas temperature. Numeric value of an exit gas stream 
temperature.
    (11) Exit gas velocity. Numeric value of an exit gas stream 
velocity.
    (12) Fall throughput (%). Portion of throughput for the 3 fall 
months (September, October, November). This represents the expression of 
annual activity information on the basis of four seasons, typically 
spring, summer, fall, and winter. It can be represented either as a 
percentage of the annual activity (e.g., production in summer is 40 
percent of the year's production), or in terms of the units of the 
activity (e.g., out of 600 units produced, spring = 150 units, summer = 
250 units, fall = 150 units, and winter = 50 units).
    (13) Federal ID code (plant). Unique codes for a plant or facility, 
containing one or more pollutant-emitting sources.
    (14) Federal ID code (point). Unique codes for the point of 
generation of emissions, typically a physical piece of equipment.
    (15) Federal ID code (stack number). Unique codes for the point 
where emissions from one or more processes are released into the 
atmosphere.
    (16) Federal Information Placement System (FIPS). The system of 
unique numeric codes developed by the government to identify States, 
counties, towns, and townships for the entire United States, Puerto 
Rico, and Guam.
    (17) Heat content. The thermal heat energy content of a solid, 
liquid, or gaseous fuel. Fuel heat content is typically expressed in 
units of Btu/lb of fuel, Btu/gal of fuel, joules/kg of fuel, etc.
    (18) Hr/day in operations. Hours per day that the emitting process 
operates.
    (19) Maximum design rate. Maximum fuel use rate based on the 
equipment's or process' physical size or operational capabilities.
    (20) Maximum nameplate capacity. A measure of the size of a 
generator which is put on the unit's nameplate by the manufacturer. The 
data element is reported in megawatts (MW) or kilowatts (KW).
    (21) Mobile source. A motor vehicle, nonroad engine or nonroad 
vehicle, where:
    (i) Motor vehicle means any self-propelled vehicle designed for 
transporting persons or property on a street or highway;
    (ii) Nonroad engine means an internal combustion engine (including 
the fuel system) that is not used in a motor vehicle or a vehicle used 
solely for competition, or that is not subject to standards promulgated 
under section 111 or section 202 of the CAA;
    (iii) Nonroad vehicle means a vehicle that is powered by a nonroad 
engine and that is not a motor vehicle or a vehicle used solely for 
competition.
    (22) Ozone season. The period May 1 through September 30 of a year.
    (23) Physical address. Street address of facility.
    (24) Point source. A non-mobile source which emits 100 tons of 
NOX or more per year unless the State designates as a point 
source a non-mobile source emitting at a specified level lower than 100 
tons of NOX per year. A non-mobile source which emits less 
NOX per year than the point source threshold is an area 
source.
    (25) Pollutant code. A unique code for each reported pollutant that 
has been assigned in the EIIP Data Model. Character names are used for 
criteria pollutants, while Chemical Abstracts Service (CAS) numbers are 
used for all other pollutants. Some States may be using storage and 
retrieval of

[[Page 156]]

aerometric data (SAROAD) codes for pollutants, but these should be able 
to be mapped to the EIIP Data Model pollutant codes.
    (26) Process rate/throughput. A measurable factor or parameter that 
is directly or indirectly related to the emissions of an air pollution 
source. Depending on the type of source category, activity information 
may refer to the amount of fuel combusted, the amount of a raw material 
processed, the amount of a product that is manufactured, the amount of a 
material that is handled or processed, population, employment, number of 
units, or miles traveled. Activity information is typically the value 
that is multiplied against an emission factor to generate an emissions 
estimate.
    (27) SCC. Source category code. A process-level code that describes 
the equipment or operation emitting pollutants.
    (28) Secondary control efficiency (%). The emissions reductions 
efficiency of a secondary control device, which shows the amount of 
reductions of a particular pollutant from a process' emissions due to 
controls or material change. Control efficiency is usually expressed as 
a percentage or in tenths.
    (29) SIC. Standard Industrial Classification code. U.S. Department 
of Commerce's categorization of businesses by their products or 
services.
    (30) Site name. The name of the facility.
    (31) Spring throughput (%). Portion of throughput or activity for 
the 3 spring months (March, April, May). See the definition of Fall 
Throughput.
    (32) Stack diameter. Stack physical diameter.
    (33) Stack height. Stack physical height above the surrounding 
terrain.
    (34) Start date (inventory year). The calendar year that the 
emissions estimates were calculated for and are applicable to.
    (35) Start time (hour). Start time (if available) that was 
applicable and used for calculations of emissions estimates.
    (36) Summer throughput (%). Portion of throughput or activity for 
the 3 summer months (June, July, August). See the definition of Fall 
Throughput.
    (37) Summer work weekday emissions. Average day's emissions for a 
typical day.
    (38) VMT by Roadway Class. This is an expression of vehicle activity 
that is used with emission factors. The emission factors are usually 
expressed in terms of grams per mile of travel. Since VMT does not 
directly correlate to emissions that occur while the vehicle is not 
moving, these non-moving emissions are incorporated into EPA's MOBILE 
model emission factors.
    (39) Week/year in operation. Weeks per year that the emitting 
process operates.
    (40) Work Weekday. Any day of the week except Saturday or Sunday.
    (41) X coordinate (latitude). East-west geographic coordinate of an 
object.
    (42) Y coordinate (longitude). North-south geographic coordinate of 
an object.

[63 FR 57496, Oct. 27, 1998]



        Subpart H--Prevention of Air Pollution Emergency Episodes

    Source: 51 FR 40668, Nov. 7, 1986, unless otherwise noted.



Sec. 51.150  Classification of regions for episode plans.

    (a) This section continues the classification system for episode 
plans. Each region is classified separately with respect to each of the 
following pollutants: Sulfur oxides, particulate matter, carbon 
monoxide, nitrogen dioxide, and ozone.
    (b) Priority I Regions means any area with greater ambient 
concentrations than the following:
    (1) Sulfur dioxide--100 g/m3 (0.04 ppm) annual 
arithmetic mean; 455 g/m3 (0.17 ppm) 24-hour 
maximum.
    (2) Particulate matter--95 g/m3 annual geometric 
mean; 325 g/m3 24-hour maximum.
    (3) Carbon monoxide--55 mg/m3 (48 ppm) 1-hour maximum; 14 
mg/m3 (12 ppm) 8-hour maximum.
    (4) Nitrogen dioxide--100 g/m3 (0.06 ppm) annual 
arithmetic mean.
    (5) Ozone--195 g/m3 (0.10 ppm) 1-hour maximum.
    (c) Priority IA Region means any area which is Priority I primarily 
because of emissions from a single point source.
    (d) Priority II Region means any area which is not a Priority I 
region and has

[[Page 157]]

ambient concentrations between the following:
    (1) Sulfur Dioxides--60-100 g/m3 (0.02-0.04 ppm) 
annual arithmetic mean; 260-445 g/m3 (0.10-0.17 ppm) 
24-hour maximum; any concentration above 1,300 g/m3 
(0.50 ppm) three-hour average.
    (2) Particulate matter--60-95 g/m3 annual 
geometric mean; 150-325 g/m3 24-hour maximum.
    (e) In the absence of adequate monitoring data, appropriate models 
must be used to classify an area under paragraph (b) of this section, 
consistent with the requirements contained in Sec. 51.112(a).
    (f) Areas which do not meet the above criteria are classified 
Priority III.

[51 FR 40668, Nov. 7, 1986, as amended at 58 FR 38822, July 20, 1993]



Sec. 51.151  Significant harm levels.

    Each plan for a Priority I region must include a contingency plan 
which must, as a mimimum, provide for taking action necessary to prevent 
ambient pollutant concentrations at any location in such region from 
reaching the following levels:

Sulfur dioxide--2.620 g/m3 (1.0 ppm) 24-hour 
average.
PM10--600 micrograms/cubic meter; 24-hour average.
Carbon monoxide--57.5 mg/m3 (50 ppm) 8-hour average; 86.3 mg/
m3 (75 ppm) 4-hour average; 144 mg/m3 (125 ppm) 1-
hour average.
Ozone--1,200 ug/m3 (0.6 ppm) 2-hour average.
Nitrogen dioxide--3.750 ug/m3 (2.0 ppm) 1-hour average; 938 
ug/m3 (0.5 ppm) 24-hour average.

[51 FR 40668, Nov. 7, 1986, as amended at 52 FR 24713, July 1, 1987]



Sec. 51.152  Contingency plans.

    (a) Each contingency plan must--
    (1) Specify two or more stages of episode criteria such as those set 
forth in appendix L to this part, or their equivalent;
    (2) Provide for public announcement whenever any episode stage has 
been determined to exist; and
    (3) Specify adequate emission control actions to be taken at each 
episode stage. (Examples of emission control actions are set forth in 
appendix L.)
    (b) Each contingency plan for a Priority I region must provide for 
the following:
    (1) Prompt acquisition of forecasts of atmospheric stagnation 
conditions and of updates of such forecasts as frequently as they are 
issued by the National Weather Service.
    (2) Inspection of sources to ascertain compliance with applicable 
emission control action requirements.
    (3) Communications procedures for transmitting status reports and 
orders as to emission control actions to be taken during an episode 
stage, including procedures for contact with public officials, major 
emission sources, public health, safety, and emergency agencies and news 
media.
    (c) Each plan for a Priority IA and II region must include a 
contingency plan that meets, as a minimum, the requirements of 
paragraphs (b)(1) and (b)(2) of this section. Areas classified Priority 
III do not need to develop episode plans.
    (d) Notwithstanding the requirements of paragraphs (b) and (c) of 
this section, the Administrator may, at his discretion--
    (1) Exempt from the requirements of this section those portions of 
Priority I, IA, or II regions which have been designated as attainment 
or unclassifiable for national primary and secondary standards under 
section 107 of the Act; or
    (2) Limit the requirements pertaining to emission control actions in 
Priority I regions to--
    (i) Urbanized areas as identified in the most recent United States 
Census, and
    (ii) Major emitting facilities, as defined by section 169(1) of the 
Act, outside the urbanized areas.



Sec. 51.153  Reevaluation of episode plans.

    (a) States should periodically reevaluate priority classifications 
of all Regions or portion of Regions within their borders. The 
reevaluation must consider the three most recent years of air quality 
data. If the evaluation indicates a change to a higher priority 
classification, appropriate changes in the episode plan must be made as 
expeditiously as practicable.
    (b) [Reserved]

[[Page 158]]



           Subpart I--Review of New Sources and Modifications

    Source: 51 FR 40669, Nov. 7, 1986, unless otherwise noted.



Sec. 51.160  Legally enforceable procedures.

    (a) Each plan must set forth legally enforceable procedures that 
enable the State or local agency to determine whether the construction 
or modification of a facility, building, structure or installation, or 
combination of these will result in--
    (1) A violation of applicable portions of the control strategy; or
    (2) Interference with attainment or maintenance of a national 
standard in the State in which the proposed source (or modification) is 
located or in a neighboring State.
    (b) Such procedures must include means by which the State or local 
agency responsible for final decisionmaking on an application for 
approval to construct or modify will prevent such construction or 
modification if--
    (1) It will result in a violation of applicable portions of the 
control strategy; or
    (2) It will interfere with the attainment or maintenance of a 
national standard.
    (c) The procedures must provide for the submission, by the owner or 
operator of the building, facility, structure, or installation to be 
constructed or modified, of such information on--
    (1) The nature and amounts of emissions to be emitted by it or 
emitted by associated mobile sources;
    (2) The location, design, construction, and operation of such 
facility, building, structure, or installation as may be necessary to 
permit the State or local agency to make the determination referred to 
in paragraph (a) of this section.
    (d) The procedures must provide that approval of any construction or 
modification must not affect the responsibility to the owner or operator 
to comply with applicable portions of the control strategy.
    (e) The procedures must identify types and sizes of facilities, 
buildings, structures, or installations which will be subject to review 
under this section. The plan must discuss the basis for determining 
which facilities will be subject to review.
    (f) The procedures must discuss the air quality data and the 
dispersion or other air quality modeling used to meet the requirements 
of this subpart.
    (1) All applications of air quality modeling involved in this 
subpart shall be based on the applicable models, data bases, and other 
requirements specified in appendix W of this part (Guideline on Air 
Quality Models).
    (2) Where an air quality model specified in appendix W of this part 
(Guideline on Air Quality Models) is inappropriate, the model may be 
modified or another model substituted. Such a modification or 
substitution of a model may be made on a case-by-case basis or, where 
appropriate, on a generic basis for a specific State program. Written 
approval of the Administrator must be obtained for any modification or 
substitution. In addition, use of a modified or substituted model must 
be subject to notice and opportunity for public comment under procedures 
set forth in Sec. 51.102.

[51 FR 40669, Nov. 7, 1986, as amended at 58 FR 38822, July 20, 1993; 60 
FR 40468, Aug. 9, 1995; 61 FR 41840, Aug. 12, 1996]



Sec. 51.161  Public availability of information.

    (a) The legally enforceable procedures in Sec. 51.160 must also 
require the State or local agency to provide opportunity for public 
comment on information submitted by owners and operators. The public 
information must include the agency's analysis of the effect of 
construction or modification on ambient air quality, including the 
agency's proposed approval or disapproval.
    (b) For purposes of paragraph (a) of this section, opportunity for 
public comment shall include, as a minimum--
    (1) Availability for public inspection in at least one location in 
the area affected of the information submitted by the owner or operator 
and of the State or local agency's analysis of the effect on air 
quality;
    (2) A 30-day period for submittal of public comment; and

[[Page 159]]

    (3) A notice by prominent advertisement in the area affected of the 
location of the source information and analysis specified in paragraph 
(b)(1) of this section.
    (c) Where the 30-day comment period required in paragraph (b) of 
this section would conflict with existing requirements for acting on 
requests for permission to construct or modify, the State may submit for 
approval a comment period which is consistent with such existing 
requirements.
    (d) A copy of the notice required by paragraph (b) of this section 
must also be sent to the Administrator through the appropriate Regional 
Office, and to all other State and local air pollution control agencies 
having jurisdiction in the region in which such new or modified 
installation will be located. The notice also must be sent to any other 
agency in the region having responsibility for implementing the 
procedures required under this subpart. For lead, a copy of the notice 
is required for all point sources. The definition of point for lead is 
given in Sec. 51.100(k)(2).



Sec. 51.162  Identification of responsible agency.

    Each plan must identify the State or local agency which will be 
responsible for meeting the requirements of this subpart in each area of 
the State. Where such responsibility rests with an agency other than an 
air pollution control agency, such agency will consult with the 
appropriate State or local air pollution control agency in carrying out 
the provisions of this subpart.



Sec. 51.163  Administrative procedures.

    The plan must include the administrative procedures, which will be 
followed in making the determination specified in paragraph (a) of 
Sec. 51.160.



Sec. 51.164  Stack height procedures.

    Such procedures must provide that the degree of emission limitation 
required of any source for control of any air pollutant must not be 
affected by so much of any source's stack height that exceeds good 
engineering practice or by any other dispersion technique, except as 
provided in Sec. 51.118(b). Such procedures must provide that before a 
State issues a permit to a source based on a good engineering practice 
stack height that exceeds the height allowed by Sec. 51.100(ii) (1) or 
(2), the State must notify the public of the availability of the 
demonstration study and must provide opportunity for public hearing on 
it. This section does not require such procedures to restrict in any 
manner the actual stack height of any source.



Sec. 51.165  Permit requirements.

    (a) State Implementation Plan provisions satisfying sections 
172(b)(6) and 173 of the Act shall meet the following conditions:
    (1) All such plans shall use the specific definitions. Deviations 
from the following wording will be approved only if the State 
specifically demonstrates that the submitted definition is more 
stringent, or at least as stringent, in all respects as the 
corresponding definition below:
    (i) Stationary source means any building, structure, facility, or 
installation which emits or may emit any air pollutant subject to 
regulation under the Act.
    (ii) Building, structure, facility, or installation means all of the 
pollutant-emitting activities which belong to the same industrial 
grouping, are located on one or more contiguous or adjacent properties, 
and are under the control of the same person (or persons under common 
control) except the activities of any vessel. Pollutant-emitting 
activities shall be considered as part of the same industrial grouping 
if they belong to the same Major Group (i.e., which have the same two-
digit code) as described in the Standard Industrial Classification 
Manual, 1972, as amended by the 1977 Supplement (U.S. Government 
Printing Office stock numbers 4101-0065 and 003-005-00176-0, 
respectively).
    (iii) Potential to emit means the maximum capacity of a stationary 
source to emit a pollutant under its physical and operational design. 
Any physical or operational limitation on the capacity of the source to 
emit a pollutant, including air pollution control equipment and 
restrictions on hours of operation or on the type or amount of material 
combusted, stored, or processed, shall be treated as part of its design 
only if the limitation or the effect it would have on emissions is 
federally

[[Page 160]]

enforceable. Secondary emissions do not count in determining the 
potential to emit of a stationary source.
    (iv)(A) Major stationary source means:
    (1) Any stationary source of air pollutants which emits, or has the 
potential to emit 100 tons per year or more of any pollutant subject to 
regulation under the Act, or
    (2) Any physical change that would occur at a stationary source not 
qualifying under paragraph (a)(1)(iv)(A)(1) as a major stationary 
source, if the change would constitute a major stationary source by 
itself.
    (B) A major stationary source that is major for volatile organic 
compounds shall be considered major for ozone
    (C) The fugitive emissions of a stationary source shall not be 
included in determining for any of the purposes of this paragraph 
whether it is a major stationary source, unless the source belongs to 
one of the following categories of stationary sources:
    (1) Coal cleaning plants (with thermal dryers);
    (2) Kraft pulp mills;
    (3) Portland cement plants;
    (4) Primary zinc smelters;
    (5) Iron and steel mills;
    (6) Primary aluminum ore reduction plants;
    (7) Primary copper smelters;
    (8) Municipal incinerators capable of charging more than 250 tons of 
refuse per day;
    (9) Hydrofluoric, sulfuric, or nitric acid plants;
    (10) Petroleum refineries;
    (11) Lime plants;
    (12) Phosphate rock processing plants;
    (13) Coke oven batteries;
    (14) Sulfur recovery plants;
    (15) Carbon black plants (furnace process);
    (16) Primary lead smelters;
    (17) Fuel conversion plants;
    (18) Sintering plants;
    (19) Secondary metal production plants;
    (20) Chemical process plants;
    (21) Fossil-fuel boilers (or combination thereof) totaling more than 
250 million British thermal units per hour heat input;
    (22) Petroleum storage and transfer units with a total storage 
capacity exceeding 300,000 barrels;
    (23) Taconite ore processing plants;
    (24) Glass fiber processing plants;
    (25) Charcoal production plants;
    (26) Fossil fuel-fired steam electric plants of more than 250 
million British thermal units per hour heat input; and
    (27) Any other stationary source category which, as of August 7, 
1980, is being regulated under section 111 or 112 of the Act.
    (v)(A) Major modification means any physical change in or change in 
the method of operation of a major stationary source that would result 
in a significant net emissions increase of any pollutant subject to 
regulation under the Act.
    (B) Any net emissions increase that is considered significant for 
volatile organic compounds shall be considered significant for ozone.
    (C) A physical change or change in the method of operation shall not 
include:
    (1) Routine maintenance, repair and replacement;
    (2) Use of an alternative fuel or raw material by reason of an order 
under sections 2 (a) and (b) of the Energy Supply and Environmental 
Coordination Act of 1974 (or any superseding legislation) or by reason 
of a natural gas curtailment plan pursuant to the Federal Power Act;
    (3) Use of an alternative fuel by reason of an order or rule section 
125 of the Act;
    (4) Use of an alternative fuel at a steam generating unit to the 
extent that the fuel is generated from municipal solid waste;
    (5) Use of an alternative fuel or raw material by a stationary 
source which;
    (i) The source was capable of accommodating before December 21, 
1976, unless such change would be prohibited under any federally 
enforceable permit condition which was established after December 12, 
1976 pursuant to 40 CFR 52.21 or under regulations approved pursuant to 
40 CFR subpart I or Sec. 51.166, or
    (ii) The source is approved to use under any permit issued under 
regulations approved pursuant to this section;

[[Page 161]]

    (6) An increase in the hours of operation or in the production rate, 
unless such change is prohibited under any federally enforceable permit 
condition which was established after December 21, 1976 pursuant to 40 
CFR 52.21 or regulations approved pursuant to 40 CFR part 51 subpart I 
or 40 CFR 51.166.
    (7) Any change in ownership at a stationary source.
    (8) The addition, replacement or use of a pollution control project 
at an existing electric utility steam generating unit, unless the 
reviewing authority determines that such addition, replacement, or use 
renders the unit less environmentally beneficial, or except:
    (i) When the reviewing authority has reason to believe that the 
pollution control project would result in a significant net increase in 
representative actual annual emissions of any criteria pollutant over 
levels used for that source in the most recent air quality impact 
analysis in the area conducted for the purpose of title I, if any, and
    (ii) The reviewing authority determines that the increase will cause 
or contribute to a violation of any national ambient air quality 
standard or PSD increment, or visibility limitation.
    (9) The installation, operation, cessation, or removal of a 
temporary clean coal technology demonstration project, provided that the 
project complies with:
    (i) The State Implementation Plan for the State in which the project 
is located, and
    (ii) Other requirements necessary to attain and maintain the 
national ambient air quality standard during the project and after it is 
terminated.
    (vi)(A) Net emissions increase means the amount by which the sum of 
the following exceeds zero:
    (1) Any increase in actual emissions from a particular physical 
change or change in the method of operation at a stationary source; and
    (2) Any other increases and decreases in actual emissions at the 
source that are contemporaneous with the particular change and are 
otherwise creditable.
    (B) An increase or decrease in actual emissions is contemporaneous 
with the increase from the particular change only if it occurs before 
the date that the increase from the particular change occurs;
    (C) An increase or decrease in actual emissions is creditable only 
if:
    (1) It occurs within a reasonable period to be specified by the 
reviewing authority; and
    (2) The reviewing authority has not relied on it in issuing a permit 
for the source under regulations approved pursuant to this section which 
permit is in effect when the increase in actual emissions from the 
particular change occurs.
    (D) An increase in actual emissions is creditable only to the extent 
that the new level of actual emissions exceeds the old level.
    (E) A decrease in actual emissions is creditable only to the extent 
that:
    (1) The old level of actual emission or the old level of allowable 
emissions whichever is lower, exceeds the new level of actual emissions;
    (2) It is federally enforceable at and after the time that actual 
construction on the particular change begins; and
    (3) The reviewing authority has not relied on it in issuing any 
permit under regulations approved pursuant to 40 CFR part 51 subpart I 
or the State has not relied on it in demonstrating attainment or 
reasonable further progress;
    (4) It has approximately the same qualitative significance for 
public health and welfare as that attributed to the increase from the 
particular change.
    (F) An increase that results from a physical change at a source 
occurs when the emissions unit on which construction occurred becomes 
operational and begins to emit a particular pollutant. Any replacement 
unit that requires shakedown becomes operational only after a reasonable 
shakedown period, not to exceed 180 days.
    (vii) Emissions unit means any part of a stationary source which 
emits or would have the potential to emit any pollutant subject to 
regulation under the the Act.
    (viii) Secondary emissons means emissions which would occur as a 
result of the construction or operation of a major stationary source or 
major modification, but do not come from the

[[Page 162]]

major stationary source or major modification itself. For the purpose of 
this section, secondary emissions must be specific, well defined, 
quantifiable, and impact the same general area as the stationary source 
or modification which causes the secondary emissions. Secondary 
emissions include emissions from any offsite support facility which 
would not be constructed or increase its emissions except as a result of 
the construction of operation of the major stationary source of major 
modification. Secondary emissions do not include any emissions which 
come directly from a mobile source such as emissions from the tailpipe 
of a motor vehicle, from a train, or from a vessel.
    (ix) Fugitive emissions means those emissions which could not 
reasonably pass through a stack, chimney, vent or other functionally 
equivalent opening.
    (x) Significant means, in reference to a net emissions increase pr 
the potential of a source to emit any of the following pollutions, as 
rate of emissions that would equal or exceed any of the following rates:

                         Pollutant Emission Rate

Carbon monoxide: 100 tons per year (tpy)
Nitrogen oxides: 40 tpy
Sulfur dioxide: 40 tpy
Ozone: 40 tpy of volatile organic compounds
Lead: 0.6 tpy

    (xi) Allowable emissions means the emissions rate of a stationary 
source calculated using the maximum rated capacity of the source (unless 
the source is subject to federally enforceable limits which restrict the 
operating rate, or hours of operation, or both) and the most stringent 
of the following:
    (A) The applicable standards set forth in 40 CFR part 60 or 61;
    (B) Any applicable State Implementation Plan emissions limitation 
including those with a future compliance date; or
    (C) The emissions rate specified as a federally enforceable permit 
condition, including those with a future compliance date.
    (xii)(A) Actual emissions means the actual rate of emissions of a 
pollutant from an emissions unit as determined in accordance with 
paragraphs (a)(1)(xii) (B) through (D) of this section.
    (B) In general, actual emissions as of a particular date shall equal 
the average rate, in tons per year, at which the unit actually emitted 
the pollutant during a two-year period which precedes the particular 
date and which is representative of normal source operation. The 
reviewing authority shall allow the use of a different time period upon 
a determination that it is more representative of normal source 
operation. Actual emissions shall be calculated using the unit's actual 
operating hours, production rates, and types of materials processed, 
stored, or combusted during the selected time period.
    (C) The reviewing authority may presume that the source-specific 
allowable emissions for the unit are equivalent to the actual emissions 
of the unit.
    (D) For any emissions unit (other than an electric utility steam 
generating unit specified in paragraph (a)(1)(xii)(E) of this section) 
which has not begun normal operations on the particular date, actual 
emissions shall equal the potential to emit of the unit on that date.
    (E) For an electric utility steam generating unit (other than a new 
unit or the replacement of an existing unit) actual emissions of the 
unit following the physical or operational change shall equal the 
representative actual annual emissions of the unit, provided the source 
owner or operator maintains and submits to the reviewing authority, on 
an annual basis for a period of 5 years from the date the unit resumes 
regular operation, information demonstrating that the physical or 
operational change did not result in an emissions increase. A longer 
period, not to exceed 10 years, may be required by the reviewing 
authority if it determines such a period to be more representative of 
normal source post-change operations.
    (xiii) Lowest achievable emission rate means, for any source, the 
more stringent rate of emissions based on the following:
    (A) The most stringent emissions limitation which is contained in 
the implementation plan of any State for such class or category of 
stationary

[[Page 163]]

source, unless the owner or operator of the proposed stationary source 
demonstrates that such limitations are not achievable; or
    (B) The most stringent emissions limitation which is achieved in 
practice by such class or category of stationary sources. This 
limitation, when applied to a modification, means the lowest achievable 
emissions rate for the new or modified emissions units within or 
stationary source. In no event shall the application of the term permit 
a proposed new or modified stationary source to emit any pollutant in 
excess of the amount allowable under an applicable new source standard 
of performance.
    (xiv) Federally enforceable means all limitations and conditions 
which are enforceable by the Administrator, including those requirements 
developed pursuant to 40 CFR parts 60 and 61, requirements within any 
applicable State implementation plan, any permit requirements 
established pursuant to 40 CFR 52.21 or under regulations approved 
pursuant to 40 CFR part 51, subpart I, including operating permits 
issued under an EPA-approved program that is incorporated into the State 
implementation plan and expressly requires adherence to any permit 
issued under such program.
    (xv) Begin actual construction means in general, initiation of 
physical on-site construction activities on an emissions unit which are 
of a permanent nature. Such activities include, but are not limited to, 
installation of building supports and foundations, laying of underground 
pipework, and construction of permanent storage structures. With respect 
to a change in method of operating this term refers to those on-site 
activities other than preparatory activities which mark the initiation 
of the change.
    (xvi) Commence as applied to construction of a major stationary 
source or major modification means that the owner or operator has all 
necessary preconstruction approvals or permits and either has:
    (A) Begun, or caused to begin, a continuous program of actual on-
site construction of the source, to be completed within a reasonable 
time; or
    (B) Entered into binding agreements or contractual obligations, 
which cannot be canceled or modified without substantial loss to the 
owner or operator, to undertake a program of actual construction of the 
source to be completed within a reasonable time.
    (xvii) Necessary preconstruction approvals or permits means those 
Federal air quality control laws and regulations and those air quality 
control laws and regulations which are part of the applicable State 
Implementation Plan.
    (xviii) Construction means any physical change or change in the 
method of operation (including fabrication, erection, installation, 
demolition, or modification of an emissions unit) which would result in 
a change in actual emissions.
    (xix)Volatile organic compounds (VOC) is as defined in 
Sec. 51.100(s) of this part.
    (xx) Electric utility steam generating unit means any steam electric 
generating unit that is constructed for the purpose of supplying more 
than one-third of its potential electric output capacity and more than 
25 MW electrical output to any utility power distribution system for 
sale. Any steam supplied to a steam distribution system for the purpose 
of providing steam to a steam-electric generator that would produce 
electrical energy for sale is also considered in determining the 
electrical energy output capacity of the affected facility.
    (xxi) Representative actual annual emissions means the average rate, 
in tons per year, at which the source is projected to emit a pollutant 
for the two-year period after a physical change or change in the method 
of operation of a unit, (or a different consecutive two-year period 
within 10 years after that change, where the reviewing authority 
determines that such period is more representative of source 
operations), considering the effect any such change will have on 
increasing or decreasing the hourly emissions rate and on projected 
capacity utilization. In projecting future emissions the reviewing 
authority shall:
    (A) Consider all relevant information, including but not limited to, 
historical operational data, the company's own representations, filings 
with the

[[Page 164]]

State or Federal regulatory authorities, and compliance plans under 
title IV of the Clean Air Act; and
    (B) Exclude, in calculating any increase in emissions that results 
from the particular physical change or change in the method of operation 
at an electric utility steam generating unit, that portion of the unit's 
emissions following the change that could have been accommodated during 
the representative baseline period and is attributable to an increase in 
projected capacity utilization at the unit that is unrelated to the 
particular change, including any increased utilization due to the rate 
of electricity demand growth for the utility system as a whole.
    (xxii) Temporary clean coal technology demonstration project means a 
clean coal technology demonstration project that is operated for a 
period of 5 years or less, and which complies with the State 
Implementation Plan for the State in which the project is located and 
other requirements necessary to attain and maintain the national ambient 
air quality standards during the project and after it is terminated.
    (xxiii) Clean coal technology means any technology, including 
technologies applied at the precombustion, combustion, or post 
combustion stage, at a new or existing facility which will achieve 
significant reductions in air emissions of sulfur dioxide or oxides of 
nitrogen associated with the utilization of coal in the generation of 
electricity, or process steam which was not in widespread use as of 
November 15, 1990.
    (xxiv) Clean coal technology demonstration project means a project 
using funds appropriated under the heading ``Department of Energy-Clean 
Coal Technology,'' up to a total amount of $2,500,000,000 for commercial 
demonstration of clean coal technology, or similar projects funded 
through appropriations for the Environmental Protection Agency. The 
Federal contribution for a qualifying project shall be at least 20 
percent of the total cost of the demonstration project.
    (xxv) Pollution control project means any activity or project at an 
existing electric utility steam generating unit for purposes of reducing 
emissions from such unit. Such activities or projects are limited to:
    (A) The installation of conventional or innovative pollution control 
technology, including but not limited to advanced flue gas 
desulfurization, sorbent injection for sulfur dioxide and nitrogen 
oxides controls and electrostatic precipitators;
    (B) An activity or project to accommodate switching to a fuel which 
is less polluting than the fuel used prior to the activity or project, 
including, but not limited to natural gas or coal reburning, or the 
cofiring of natural gas and other fuels for the purpose of controlling 
emissions;
    (C) A permanent clean coal technology demonstration project 
conducted under title II, sec. 101(d) of the Further Continuing 
Appropriations Act of 1985 (sec. 5903(d) of title 42 of the United 
States Code), or subsequent appropriations, up to a total amount of 
$2,500,000,000 for commercial demonstration of clean coal technology, or 
similar projects funded through appropriations for the Environmental 
Protection Agency; or
    (D) A permanent clean coal technology demonstration project that 
constitutes a repowering project.
    (2) Each plan shall adopt a preconstruction review program to 
satisfy the requirements of sections 172(b)(6) and 173 of the Act for 
any area designated nonattainment for any national ambient air quality 
standard under 40 CFR 81.300 et seq. Such a program shall apply to any 
new major stationary source or major modification that is major for the 
pollutant for which the area is designated nonattainment, if the 
stationary source or modification would locate anywhere in the 
designated nonattainment area.
    (3)(i) Each plan shall provide that for sources and modifications 
subject to any preconstruction review program adopted pursuant to this 
subsection the baseline for determining credit for emissions reductions 
is the emissions limit under the applicable State Implementation Plan in 
effect at the time the application to construct is filed, except that 
the offset baseline shall be the actual emissions of the source from 
which offset credit is obtained where;

[[Page 165]]

    (A) The demonstration of reasonable further progress and attainment 
of ambient air quality standards is based upon the actual emissions of 
sources located within a designated nonattainment area for which the 
preconstruction review program was adopted; or
    (B) The applicable State Implementation Plan does not contain an 
emissions limitation for that source or source category.
    (ii) The plan shall further provide that:
    (A) Where the emissions limit under the applicable State 
Implementation Plan allows greater emissions than the potential to emit 
of the source, emissions offset credit will be allowed only for control 
below this potential;
    (B) For an existing fuel combustion source, credit shall be based on 
the allowable emissions under the applicable State Implementation Plan 
for the type of fuel being burned at the time the application to 
construct is filed. If the existing source commits to switch to a 
cleaner fuel at some future date, emissions offset credit based on the 
allowable (or actual) emissions for the fuels involved is not 
acceptable, unless the permit is conditioned to require the use of a 
specified alternative control measure which would achieve the same 
degree of emissions reduction should the source switch back to a dirtier 
fuel at some later date. The reviewing authority should ensure that 
adequate long-term supplies of the new fuel are available before 
granting emissions offset credit for fuel switches,
    (C)(1) Emissions reductions achieved by shutting down an existing 
source or curtailing production or operating hours below baseline levels 
may be generally credited if such reductions are permanent, 
quantifiable, and federally enforceable, and if the area has an EPA-
approved attainment plan. In addition, the shutdown or curtailment is 
creditable only if it occurred on or after the date specified for this 
purpose in the plan, and if such date is on or after the date of the 
most recent emissions inventory used in the plan's demonstration of 
attainment. Where the plan does not specify a cutoff date for shutdown 
credits, the date of the most recent emissions inventory or attainment 
demonstration, as the case may be, shall apply. However, in no event may 
credit be given for shutdowns which occurred prior to August 7, 1977. 
For purposes of this paragraph, a permitting authority may choose to 
consider a prior shutdown or curtailment to have occurred after the date 
of its most recent emissions inventory, if the inventory explicitly 
includes as current existing emissions the emissions from such 
previously shutdown or curtailed sources.
    (2) Such reductions may be credited in the absence of an approved 
attainment demonstration only if the shutdown or curtailment occurred on 
or after the date the new source permit application is filed, or, if the 
applicant can establish that the proposed new source is a replacement 
for the shutdown or curtailed source, and the cutoff date provisions of 
Sec. 51.165(a)(3)(ii)(C)(1) are observed.
    (D) No emissions credit may be allowed for replacing one hydrocarbon 
compound with another of lesser reactivity, except for those compounds 
listed in Table 1 of EPA's ``Recommended Policy on Control of Volatile 
Organic Compounds'' (42 FR 35314, July 8, 1977; (This document is also 
available from Mr. Ted Creekmore, Office of Air Quality Planning and 
Standards, (MD-15) Research Triangle Park, NC 27711.))
    (E) All emission reductions claimed as offset credit shall be 
federally enforceable;
    (F) Procedures relating to the permissible location of offsetting 
emissions shall be followed which are at least as stringent as those set 
out in 40 CFR part 51 appendix S section IV.D.
    (G) Credit for an emissions reduction can be claimed to the extent 
that the reviewing authority has not relied on it in issuing any permit 
under regulations approved pursuant to 40 CFR part 51 subpart I or the 
State has not relied on it in demonstration attainment or reasonable 
further progress.
    (4) Each plan may provide that the provisions of this paragraph do 
not apply to a source or modification that would be a major stationary 
source or major modification only if fugitive emission to the extent 
quantifiable are considered in calculating the potential to emit of the 
stationary source or

[[Page 166]]

modification and the source does not belong to any of the following 
categories:
    (i) Coal cleaning plants (with thermal dryers);
    (ii) Kraft pulp mills;
    (iii) Portland cement plants;
    (iv) Primary zinc smelters;
    (v) Iron and steel mills;
    (vi) Primary aluminum ore reduction plants;
    (vii) Primary copper smelters;
    (viii) Municipal incinerators capable of charging more than 250 tons 
of refuse per day;
    (ix) Hydrofluoric, sulfuric, or citric acid plants;
    (x) Petroleum refineries;
    (xi) Lime plants;
    (xii) Phosphate rock processing plants;
    (xiii) Coke oven batteries;
    (xiv) Sulfur recovery plants;
    (xv) Carbon black plants (furnace process);
    (xvi) Primary lead smelters;
    (xvii) Fuel conversion plants;
    (xviii) Sintering plants;
    (xix) Secondary metal production plants;
    (xx) Chemical process plants;
    (xxi) Fossil-fuel boilers (or combination thereof) totaling more 
than 250 million British thermal units per hour heat input;
    (xxii) Petroleum storage and transfer units with a total storage 
capacity exceeding 300,000 barrels;
    (xxiii) Taconite ore processing plants;
    (xxiv) Glass fiber processing plants;
    (xxv) Charcoal production plants;
    (xxvi) Fossil fuel-fired steam electric plants of more than 250 
million British thermal units per hour heat input;
    (xxvii) Any other stationary source category which, as of August 7, 
1980, is being regulated under section 111 or 112 of the Act.
    (5) Each plan shall include enforceable procedures to provide that:
    (i) Approval to construct shall not relieve any owner or operator of 
the responsibility to comply fully with applicable provision of the plan 
and any other requirements under local, State or Federal law.
    (ii) At such time that a particular source or modification becomes a 
major stationary source or major modification solely by virtue of a 
relaxation in any enforcement limitation which was established after 
August 7, 1980, on the capacity of the source or modification otherwise 
to emit a pollutant, such as a restriction on hours of operation, then 
the requirements of regulations approved pursuant to this section shall 
apply to the source or modification as though construction had not yet 
commenced on the source or modification;
    (b)(1) Each plan shall include a preconstruction review permit 
program or its equivalent to satisfy the requirements of section 
110(a)(2)(D)(i) of the Act for any new major stationary source or major 
modification as defined in paragraphs (a)(1) (iv) and (v) of this 
section. Such a program shall apply to any such source or modification 
that would locate in any area designated as attainment or unclassifiable 
for any national ambient air quality standard pursuant to section 107 of 
the Act, when it would cause or contribute to a violation of any 
national ambient air quality standard.
    (2) A major source or major modification will be considered to cause 
or contribute to a violation of a national ambient air quality standard 
when such source or modification would, at a minimum, exceed the 
following significance levels at any locality that does not or would not 
meet the applicable national standard:

--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                Averaging time (hours)
             Pollutant                       Annual         --------------------------------------------------------------------------------------------
                                                                       24                      8                      3                      1
--------------------------------------------------------------------------------------------------------------------------------------------------------
SO2................................  1.0 g/m\3\...  5 g/m\3\.....    ...................  25 g/m\3\...
PM10...............................  1.0 g/m\3\...  5 g/m\3\.....    ...................    ...................
NO2................................  1.0 g/m\3\...    ....................    ...................    ...................
CO.................................    ....................    ....................  0.5 mg/m\3\..........    ...................  2 mg/m\3\
--------------------------------------------------------------------------------------------------------------------------------------------------------


[[Page 167]]

    (3) Such a program may include a provision which allows a proposed 
major source or major modification subject to paragraph (b) of this 
section to reduce the impact of its emissions upon air quality by 
obtaining sufficient emission reductions to, at a minimum, compensate 
for its adverse ambient impact where the major source or major 
modification would otherwise cause or contribute to a violation of any 
national ambient air quality standard. The plan shall require that, in 
the absence of such emission reductions, the State or local agency shall 
deny the proposed construction.
    (4) The requirements of paragraph (b) of this section shall not 
apply to a major stationary source or major modification with respect to 
a particular pollutant if the owner or operator demonstrates that, as to 
that pollutant, the source or modification is located in an area 
designated as nonattainment pursuant to section 107 of the Act.

[51 FR 40669, Nov. 7, 1986, as amended at 52 FR 24713, July 1, 1987; 52 
FR 29386, Aug 7, 1987; 54 FR 27285, 27299 June 28, 1989; 57 FR 3946, 
Feb. 3, 1992; 57 FR 32334, July 21, 1992]



Sec. 51.166  Prevention of significant deterioration of air quality.

    (a)(1) Plan requirements. In accordance with the policy of section 
101(b)(1) of the act and the purposes of section 160 of the Act, each 
applicable State implementation plan shall contain emission limitations 
and such other measures as may be necessary to prevent significant 
deterioration of air quality.
    (2) Plan revisions. If a State Implementation Plan revision would 
result in increased air quality deterioration over any baseline 
concentration, the plan revision shall include a demonstration that it 
will not cause or contribute to a violation of the applicable 
increment(s). If a plan revision proposing less restrictive requirements 
was submitted after August 7, 1977 but on or before any applicable 
baseline date and was pending action by the Administrator on that date, 
no such demonstration is necessary with respect to the area for which a 
baseline date would be established before final action is taken on the 
plan revision. Instead, the assessment described in paragraph (a)(4) of 
this section, shall review the expected impact to the applicable 
increment(s).
    (3) Required plan revision. If the State or the Administrator 
determines that a plan is substantially inadequate to prevent 
significant deterioration or that an applicable increment is being 
violated, the plan shall be revised to correct the inadequacy or the 
violation. The plan shall be revised within 60 days of such a finding by 
a State or within 60 days following notification by the Administrator, 
or by such later date as prescribed by the Administrator after 
consultation with the State.
    (4) Plan assessment. The State shall review the adequacy of a plan 
on a periodic basis and within 60 days of such time as information 
becomes available that an applicable increment is being violated.
    (5) Public participation. Any State action taken under this 
paragraph shall be subject to the opportunity for public hearing in 
accordance with procedures equivalent to those established in 
Sec. 51.102.
    (6) Amendments. (i) Any State required to revise its implementation 
plan by reason of an amendment to this section, including any amendment 
adopted simultaneously with this paragraph, shall adopt and submit such 
plan revision to the Administrator for approval within 9 months after 
the effective date of the new amendments.
    (ii) Any revision to an implementation plan that would amend the 
provisions for the prevention of significant air quality deterioration 
in the plan shall specify when and as to what sources and modifications 
the revision is to take effect.
    (iii) Any revision to an implementation plan that an amendment to 
this section required shall take effect no later than the date of its 
approval and may operate prospectively.
    (b) Definitions. All State plans shall use the following definitions 
for the purposes of this section. Deviations from the following wording 
will be approved only if the State specifically demonstrates that the 
submitted definition is more stringent, or at least as stringent, in all 
respects as the corresponding definitions below:
    (1)(i) Major stationary source means:

[[Page 168]]

    (a) Any of the following stationary sources of air pollutants which 
emits, or has the potential to emit, 100 tons per year or more of any 
pollutant subject to regulation under the Act: Fossil fuel-fired steam 
electric plants of more than 250 million British thermal units per hour 
heat input, coal cleaning plants (with thermal dryers), kraft pulp 
mills, portland cement plants, primary zinc smelters, iron and steel 
mill plants, primary aluminum ore reduction plants, primary copper 
smelters, municipal incinerators capable of charging more than 250 tons 
of refuse per day, hydrofluoric, sulfuric, and nitric acid plants, 
petroleum refineries, lime plants, phosphate rock processing plants, 
coke oven batteries, sulfur recovery plants, carbon black plants 
(furnace process), primary lead smelters, fuel conversion plants, 
sintering plants, secondary metal production plants, chemical process 
plants, fossil fuel boilers (or combinations thereof) totaling more than 
250 million British thermal units per hour heat input, petroleum storage 
and transfer units with a total storage capacity exceeding 300,000 
barrels, taconite ore processing plants, glass fiber processing plants, 
and charcoal production plants;
    (b) Notwithstanding the stationary source size specified in 
paragraph (b)(1)(i)(a) of this section, any stationary source which 
emits, or has the potential to emit, 250 tons per year or more of any 
air pollutant subject to regulation under the Act; or
    (c) Any physical change that would occur at a stationary source not 
otherwise qualifying under paragraph (b)(1) of this section, as a major 
stationary source if the change would constitute a major stationary 
source by itself.
    (ii) A major source that is major for volatile organic compounds 
shall be considered major for ozone.
    (iii) The fugitive emissions of a stationary source shall not be 
included in determining for any of the purposes of this section whether 
it is a major stationary source, unless the source belongs to one of the 
following categories of stationary sources:
    (a) Coal cleaning plants (with thermal dryers);
    (b) Kraft pulp mills;
    (c) Portland cement plants;
    (d) Primary zinc smelters;
    (e) Iron and steel mills;
    (f) Primary aluminum ore reduction plants;
    (g) Primary copper smelters;
    (h) Municipal incinerators capable of charging more than 250 tons of 
refuse per day;
    (i) Hydrofluoric, sulfuric, or nitric acid plants;
    (j) Petroleum refineries;
    (k) Lime plants;
    (l) Phosphate rock processing plants;
    (m) Coke oven batteries;
    (n) Sulfur recovery plants;
    (o) Carbon black plants (furnace process);
    (p) Primary lead smelters;
    (q) Fuel conversion plants;
    (r) Sintering plants;
    (s) Secondary metal production plants;
    (t) Chemical process plants;
    (u) Fossil-fuel boilers (or combination thereof) totaling more than 
250 million British thermal units per hour heat input;
    (v) Petroleum storage and transfer units with a total storage 
capacity exceeding 300,000 barrels;
    (w) Taconite ore processing plants;
    (x) Glass fiber processing plants;
    (y) Charcoal production plants;
    (z) Fossil fuel-fired steam electric plants of more that 250 million 
British thermal units per hour heat input;
    (aa) Any other stationary source category which, as of August 7, 
1980, is being regulated under section 111 or 112 of the Act.
    (2)(i) Major modification means any physical change in or change in 
the method of operation of a major stationary source that would result 
in a significant net emissions increase of any pollutant subject to 
regulation under the Act.
    (ii) Any net emissions increase that is significant for volatile 
organic compounds shall be considered significant for ozone.
    (iii) A physical change or change in the method of operation shall 
not include:
    (a) Routine maintenance, repair, and replacement;
    (b) Use of an alternative fuel or raw material by reason of any 
order under

[[Page 169]]

section 2 (a) and (b) of the Energy Supply and Environmental 
Coordination Act of 1974 (or any superseding legislation) or by reason 
of a natural gas curtailment plan pursuant to the Federal Power Act;
    (c) Use of an alternative fuel by reason of an order or rule under 
section 125 of the Act;
    (d) Use of an alternative fuel at a steam generating unit to the 
extent that the fuel is generated from municipal solid waste;
    (e) Use of an alternative fuel or raw material by a stationary 
source which:
    (1) The source was capable of accommodating before January 6, 1975, 
unless such change would be prohibited under any federally enforceable 
permit condition which was established after January 6, 1975 pursuant to 
40 CFR 52.21 or under regulations approved pursuant to 40 CFR subpart I 
or Sec. 51.166; or
    (2) The source is approved to use under any permit issued under 40 
CFR 52.21 or under regulations approved pursuant to 40 CFR 51.166;
    (f) An increase in the hours of operation or in the production rate, 
unless such change would be prohibited under any federally enforceable 
permit condition which was established after January 6, 1975, pursuant 
to 40 CFR 52.21 or under regulations approved pursuant to 40 CFR subpart 
I or Sec. 51.166.
    (g) Any change in ownership at a stationary source.
    (h) The addition, replacement or use of a pollution control project 
at an existing electric utility steam generating unit, unless the 
Administrator determines that such addition, replacement, or use renders 
the unit less environmentally beneficial, or except:
    (1) When the reviewing authority has reason to believe that the 
pollution control project would result in a significant net increase in 
representative actual annual emissions of any criteria pollutant over 
levels used for that source in the most recent air quality impact 
analysis in the area conducted for the purpose of title I, if any, and
    (2) The reviewing authority determines that the increase will cause 
or contribute to a violation of any national ambient air quality 
standard or PSD increment, or visibility limitation.
    (i) The installation, operation, cessation, or removal of a 
temporary clean coal technology demonstration project, provided that the 
project complies with:
    (1) The State implementation plan for the State in which the project 
is located; and
    (2) Other requirements necessary to attain and maintain the national 
ambient air quality standards during the project and after it is 
terminated.
    (j) The installation or operation of a permanent clean coal 
technology demonstration project that constitutes repowering, provided 
that the project does not result in an increase in the potential to emit 
of any regulated pollutant emitted by the unit. This exemption shall 
apply on a pollutant-by-pollutant basis.
    (k) The reactivation of a very clean coal-fired electric utility 
steam generating unit.
    (3)(i) Net emissions increase means the amount by which the sum of 
the following exceeds zero:
    (a) Any increase in actual emissions from a particular physical 
change or change in the method of operation at a stationary source; and
    (b) Any other increases and decreases in actual emissions at the 
source that are contemporaneous with the particular change and are 
otherwise creditable.
    (ii) An increase or decrease in actual emissions is contemporaneous 
with the increase from the particular change only if it occurs within a 
reasonable period (to be specified by the State) before the date that 
the increase from the particular change occurs.
    (iii) An increase or decrease in actual emissions is creditable only 
if the reviewing authority has not relied on it in issuing a permit for 
the source under regulations approved pursuant to this section, which 
permit is in effect when the increase in actual emissions from the 
particular change occurs.
    (iv) An increase or decrease in actual emissions of sulfur dioxide, 
particulate matter, or nitrogen oxides, which occurs before the 
applicable minor source baseline date is creditable only if it is 
required to be considered in calculating the amount of maximum allowable 
increases remaining available.

[[Page 170]]

With respect to particulate matter, only PM-10 emissions can be used to 
evaluate the net emissions increase for PM-10.
    (v) An increase in actual emissions is creditable only to the extent 
that the new level of actual emissions exceeds the old level.
    (vi) A decrease in actual emissions is creditable only to the extent 
that:
    (a) The old level of actual emissions or the old level of allowable 
emissions, whichever is lower, exceeds the new level of actual 
emissions;
    (b) It is federally enforceable at and after the time that actual 
construction on the particular change begins; and
    (c) It has approximately the same qualitative significance for 
public health and welfare as that attributed to the increase from the 
particular change.
    (vii) An increase that results from a physical change at a source 
occurs when the emissions unit on which construction occurred becomes 
operational and begins to emit a particular pollutant. Any replacement 
unit that requires shakedown becomes operational only after a reasonable 
shakedown period, not to exceed 180 days.
    (4) Potential to emit means the maximum capacity of a stationary 
source to emit a pollutant under its physical and operational design. 
Any physical or operational limitation on the capacity of the source to 
emit a pollutant, including air pollution control equipment and 
restrictions on hours of operation or on the type or amount of material 
combusted, stored, or processed, shall be treated as part of its design 
if the limitation or the effect it would have on emissions is federally 
enforceable. Secondary emissions do not count in determining the 
potential to emit of a stationary source.
    (5) Stationary source means any building, structure, facility, or 
installation which emits or may emit any air pollutant subject to 
regulation under the Act.
    (6) Building, structure, facility, or installation means all of the 
pollutant-emitting activities which belong to the same industrial 
grouping, are located on one or more contiguous or adjacent properties, 
and are under the control of the same person (or persons under common 
control) except the activities of any vessel. Pollutant-emitting 
activities shall be considered as part of the same industrial grouping 
if they belong to the same Major Group (i.e., which have the same two-
digit code) as described in the Standard Industrial Classification 
Manual, 1972, as amended by the 1977 Supplement (U.S. Government 
Printing Office stock numbers 4101-0066 and 003-005-00176-0, 
respectively).
    (7) Emissions unit means any part of a stationary source which emits 
or would have the potential to emit any pollutant subject to regulation 
under the Act.
    (8) Construction means any physical change or change in the method 
of operation (including fabrication, erection, installation, demolition, 
or modification of an emissions unit) which would result in a change in 
actual emissions.
    (9) Commence as applied to construction of a major stationary source 
or major modification means that the owner or operator has all necessary 
preconstruction approvals or permits and either has:
    (i) Begun, or caused to begin, a continuous program of actual on-
site construction of the source, to be completed within a reasonable 
time; or
    (ii) Entered into binding agreements or contractual obligations, 
which cannot be cancelled or modified without substantial loss to the 
owner or operator, to undertake a program of actual construction of the 
source to be completed within a reasonable time.
    (10) Necessary preconstruction approvals or permits means those 
permits or approvals required under Federal air quality control laws and 
regulations and those air quality control laws and regulations which are 
part of the applicable State Implementation Plan.
    (11) Begin actual construction means, in general, initiation of 
physical on-site construction activities on an emissions unit which are 
of a permanent nature. Such activities include, but are not limited to, 
installation of building supports and foundations, laying of underground 
pipework, and construction of permanent storage structures. With respect 
to a change in method of operation this term refers to those on-site

[[Page 171]]

activities, other than preparatory activities, which mark the initiation 
of the change.
    (12) Best available control technology means an emissions limitation 
(including a visible emissions standard) based on the maximum degree of 
reduction for each pollutant subject to regulation under the Act which 
would be emitted from any proposed major stationary source or major 
modification which the reviewing authority, on a case-by-case basis, 
taking into account energy, environmental, and economic impacts and 
other costs, determines is achievable for such source or modification 
through application of production processes or available methods, 
systems, and techniques, including fuel cleaning or treatment or 
innovative fuel combination techniques for control of such pollutant. In 
no event shall application of best available control technology result 
in emissions of any pollutant which would exceed the emissions allowed 
by any applicable standard under 40 CFR parts 60 and 61. If the 
reviewing authority determines that technological or economic 
limitations on the application of measurement methodology to a 
particular emissions unit would make the imposition of an emissions 
standard infeasible, a design, equipment, work practice, operational 
standard or combination thereof, may be prescribed instead to satisfy 
the requirement for the application of best available control 
technology. Such standard shall, to the degree possible, set forth the 
emissions reduction achievable by implementation of such design, 
equipment, work practice or operation, and shall provide for compliance 
by means which achieve equivalent results.
    (13)(i) Baseline concentration means that ambient concentration 
level which exists in the baseline area at the time of the applicable 
minor source baseline date. A baseline concentration is determined for 
each pollutant for which a minor source baseline date is established and 
shall include:
    (a) The actual emissions representative of sources in existence on 
the applicable minor source baseline date, except as provided in 
paragraph (b)(13)(ii) of this section;
    (b) The allowable emissions of major stationary sources which 
commenced construction before the major source baseline date, but were 
not in operation by the applicable minor source baseline date.
    (ii) The following will not be included in the baseline 
concentration and will affect the applicable maximum allowable 
increase(s):
    (a) Actual emissions from any major stationary source on which 
construction commenced after the major source baseline date; and
    (b) Actual emissions increases and decreases at any stationary 
source occurring after the minor source baseline date.
    (14)(i) Major source baseline date means:
    (a) In the case of particulate matter and sulfur dioxide, January 6, 
1975, and
    (b) In the case of nitrogen dioxide, February 8, 1988.
    (ii) Minor source baseline date means the earliest date after the 
trigger date on which a major stationary source or a major modification 
subject to 40 CFR 52.21 or to regulations approved pursuant to 40 CFR 
51.166 submits a complete application under the relevant regulations. 
The trigger date is:
    (a) In the case of particulate matter and sulfur dioxide, August 7, 
1977, and
    (b) In the case of nitrogen dioxide, February 8, 1988.
    (iii) The baseline date is established for each pollutant for which 
increments or other equivalent measures have been established if:
    (a) The area in which the proposed source or modification would 
construct is designated as attainment or unclassifiable under section 
107(d)(i) (D) or (E) of the Act for the pollutant on the date of its 
complete application under 40 CFR 52.21 or under regulations approved 
pursuant to 40 CFR 51.166; and
    (b) In the case of a major stationary source, the pollutant would be 
emitted in significant amounts, or, in the case of a major modification, 
there would be a significant net emissions increase of the pollutant.
    (iv) Any minor source baseline date established originally for the 
TSP increments shall remain in effect and shall apply for purposes of 
determining

[[Page 172]]

the amount of available PM-10 increments, except that the reviewing 
authority may rescind any such minor source baseline date where it can 
be shown, to the satisfaction of the reviewing authority, that the 
emissions increase from the major stationary source, or the net 
emissions increase from the major modification, responsible for 
triggering that date did not result in a significant amount of PM-10 
emissions.
    (15)(i) Baseline area means any intrastate area (and every part 
thereof) designated as attainment or unclassifiable under section 
107(d)(1) (D) or (E) of the Act in which the major source or major 
modification establishing the minor source baseline date would construct 
or would have an air quality impact equal to or greater than 1 
g/m\3\ (annual average) of the pollutant for which the minor 
source baseline date is established.
    (ii) Area redesignations under section 107(d)(1) (D) or (E) of the 
Act cannot intersect or be smaller than the area of impact of any major 
stationary source or major modification which:
    (a) Establishes a minor source baseline date; or
    (b) Is subject to 40 CFR 52.21 or under regulations approved 
pursuant to 40 CFR 51.166, and would be constructed in the same State as 
the State proposing the redesignation.
    (iii) Any baseline area established originally for the TSP 
increments shall remain in effect and shall apply for purposes of 
determining the amount of available PM-10 increments, except that such 
baseline area shall not remain in effect if the permit authority 
rescinds the corresponding minor source baseline date in accordance with 
paragraph (b)(14)(iv) of this section.
    (16) Allowable emissions means the emissions rate of a stationary 
source calculated using the maximum rated capacity of the source (unless 
the source is subject to federally enforceable limits which restrict the 
operating rate, or hours of operation, or both) and the most stringent 
of the following:
    (i) The applicable standards as set forth in 40 CFR parts 60 and 61;
    (ii) The applicable State Implementation Plan emissions limitation, 
including those with a future compliance date; or
    (iii) The emissions rate specified as a federally enforceable permit 
condition.
    (17) Federally enforceable means all limitations and conditions 
which are enforceable by the Administrator, including those requirements 
developed pursuant to 40 CFR parts 60 and 61, requirements within any 
applicable State implementation plan, any permit requirements 
established pursuant to 40 CFR 52.21 or under regulations approved 
pursuant to 40 CFR part 51, subpart I, including operating permits 
issued under an EPA-approved program that is incorporated into the State 
implementation plan and expressly requires adherence to any permit 
issued under such program.
    (18) Secondary emissions means emissions which occur as a result of 
the construction or operation of a major stationary source or major 
modification, but do not come from the major stationary source or major 
modification itself. For the purposes of this section, secondary 
emissions must be specific, well defined, quantifiable, and impact the 
same general areas the stationary source modification which causes the 
secondary emissions. Secondary emissions include emissions from any 
offsite support facility which would not be constructed or increase its 
emissions except as a result of the construction or operation of the 
major stationary source or major modification. Secondary emissions do 
not include any emissions which come directly from a mobile source, such 
as emissions from the tailpipe of a motor vehicle, from a train, or from 
a vessel.
    (19) Innovative control technology means any system of air pollution 
control that has not been adequately demonstrated in practice, but would 
have a substantial likelihood of achieving greater continuous emissions 
reduction than any control system in current practice or of achieving at 
least comparable reductions at lower cost in terms of energy, economics, 
or nonair quality environmental impacts.
    (20) Fugitive emissions means those emissions which could not 
reasonably pass through a stack, chimney, vent, or other functionally 
equivalent opening.

[[Page 173]]

    (21)(i) Actual emissions means the actual rate of emissions of a 
pollutant from an emissions unit, as determined in accordance with 
paragraphs (b)(21) (ii) through (iv) of this section.
    (ii) In general, actual emissions as of a particular date shall 
equal the average rate, in tons per year, at which the unit actually 
emitted the pollutant during a two-year period which precedes the 
particular date and which is representative of normal source operation. 
The reviewing authority may allow the use of a different time period 
upon a determination that it is more representative of normal source 
operation. Actual emissions shall be calculated using the unit's actual 
operating hours, production rates, and types of materials processed, 
stored, or combusted during the selected time period.
    (iii) The reviewing authority may presume that source-specific 
allowable emissions for the unit are equivalent to the actual emissions 
of the unit.
    (iv) For any emissions unit (other than an electric utility steam 
generating unit specified in paragraph (b)(21)(v) of this section) which 
has not begun normal operations on the particular date, actual emissions 
shall equal the potential to emit of the unit on that date.
    (v) For an electric utility steam generating unit (other than a new 
unit or the replacement of an existing unit) actual emissions of the 
unit following the physical or operational change shall equal the 
representative actual annual emissions of the unit following the 
physical or operational change, provided the source owner or operator 
maintains and submits to the reviewing authority, on an annual basis for 
a period of 5 years from the date the unit resumes regular operation, 
information demonstrating that the physical or operational change did 
not result in an emissions increase. A longer period, not to exceed 10 
years, may be required by the reviewing authority if it determines such 
a period to be more representative of normal source post-change 
operations.
    (22) Complete means, in reference to an application for a permit, 
that the application contains all the information necessary for 
processing the application. Designating an application complete for 
purposes of permit processing does not preclude the reviewing authority 
from requesting or accepting any additional information.
    (23)(i) Significant means, in reference to a net emissions increase 
or the potential of a source to emit any of the following pollutants, a 
rate of emissions that would equal or exceed any of the following rates:

                      Pollutant and Emissions Rate

Carbon monoxide: 100 tons per year (tpy)
Nitrogen oxides: 40 tpy
Sulfur dioxide: 40 tpy
Particulate matter: 25 tpy of particulate matter emissions. 15 tpy of 
PM10 emissions.
Ozone: 40 tpy of volatile organic compounds
Lead: 0.6 tpy
Asbestos: 0.007 tpy
Beryllium: 0.0004 tpy
Mercury: 0.1 tpy
Vinyl chloride: 1 tpy
Fluorides: 3 tpy
Sulfuric acid mist: 7 tpy
Hydrogen sulfide (H2 S): 10 tpy
Total reduced sulfur (including H2 S): 10 tpy
Reduced sulfur compounds (including H2 S): 10 tpy
Municipal waste combustor organics (measured as total tetra- through 
octa-chlorinated dibenzo-p-dioxins and dibenzofurans): 3.2  x  
10-6 megagrams per year (3.5  x  10-6 tons per 
year)
Municipal waste combustor metals (measured as articulate matter): 14 
megagrams per year (15 tons per year) Municipal waste combustor acid 
gases (measured as sulfur dioxide and hydrogen chloride): 36 megagrams 
per year (40 tons per year)
Municipal solid waste landfill emissions (measured as nonmethane organic 
compounds): 45 megagrams per year (50 tons per year)

    (ii) Significant means, in reference to a net emissions increase or 
the potential of a source to emit a pollutant subject to regulation 
under the Act that paragraph (b)(23)(i) of this section, does not list, 
any emissions rate.
    (iii) Notwithstanding paragraph (b)(23)(i) of this section, 
significant means any emissions rate or any net emissions increase 
associated with a major stationary source or major modification, which 
would construct within 10 kilometers of a Class I area, and have an 
impact on such area equal to or greater than 1 g/m3 
(24-hour average).

[[Page 174]]

    (24) Federal Land Manager means, with respect to any lands in the 
United States, the Secretary of the department with authority over such 
lands.
    (25) High terrain means any area having an elevation 900 feet or 
more above the base of the stack of a source.
    (26) Low terrain means any area other than high terrain.
    (27) Indian Reservation means any federally recognized reservation 
established by Treaty, Agreement, Executive Order, or Act of Congress.
    (28) Indian Governing Body means the governing body of any tribe, 
band, or group of Indians subject to the jurisdiction of the United 
States and recognized by the United States as possessing power of self-
government.
    (29) Volatile organic compounds (VOC) is as defined in 
Sec. 51.100(s) of this part.
    (30) Electric utility steam generating unit means any steam electric 
generating unit that is constructed for the purpose of supplying more 
than one-third of its potential electric output capacity and more than 
25 MW electrical output to any utility power distribution system for 
sale. Any steam supplied to a steam distribution system for the purpose 
of providing steam to a steam-electric generator that would produce 
electrical energy for sale is also considered in determining the 
electrical energy output capacity of the affected facility.
    (31) Pollution control project means any activity or project 
undertaken at an existing electric utility steam generating unit for 
purposes of reducing emissions from such unit. Such activities or 
projects are limited to:
    (i) The installation of conventional or innovative pollution control 
technology, including but not limited to advanced flue gas 
desulfurization, sorbent injection for sulfur dioxide and nitrogen 
oxides controls and electrostatic precipitators;
    (ii) An activity or project to accommodate switching to a fuel which 
is less polluting than the fuel used prior to the activity or project, 
including but not limited to natural gas or coal re-burning, or the co-
firing of natural gas and other fuels for the purpose of controlling 
emissions;
    (iii) A permanent clean coal technology demonstration project 
conducted under title II, section 101(d) of the Further Continuing 
Appropriations Act of 1985 (section 5903(d) of title 42 of the United 
States Code), or subsequent appropriations, up to a total amount of 
$2,500,000,000 for commercial demonstration of clean coal technology, or 
similar projects funded through appropriations for the Environmental 
Protection Agency, or
    (iv) A permanent clean coal technology demonstration project that 
constitutes a repowering project.
    (32) Representative actual annual emissions means the average rate, 
in tons per year, at which the source is projected to emit a pollutant 
for the two-year period after a physical change or change in the method 
of operation of a unit, (or a different consecutive two-year period 
within 10 years after that change, where the reviewing authority 
determines that such period is more representative of normal source 
operations), considering the effect any such change will have on 
increasing or decreasing the hourly emissions rate and on projected 
capacity utilization. In projecting future emissions the reviewing 
authority shall:
    (i) Consider all relevant information, including but not limited to, 
historical operational data, the company's own representations, filings 
with the State or Federal regulatory authorities, and compliance plans 
under title IV of the Clean Air Act; and
    (ii) Exclude, in calculating any increase in emissions that results 
from the particular physical change or change in the method of operation 
at an electric utility steam generating unit, that portion of the unit's 
emissions following the change that could have been accommodated during 
the representative baseline period and is attributable to an increase in 
projected capacity utilization at the unit that is unrelated to the 
particular change, including any increased utilization due to the rate 
of electricity demand growth for the utility system as a whole.
    (33) Clean coal technology means any technology, including 
technologies applied at the precombustion, combustion, or post 
combustion stage, at a new or existing facility which will achieve 
significant reductions in air

[[Page 175]]

emissions of sulfur dioxide or oxides of nitrogen associated with the 
utilization of coal in the generation of electricity, or process steam 
which was not in widespread use as of November 15, 1990.
    (34) Clean coal technology demonstration project means a project 
using funds appropriated under the heading ``Department of Energy--Clean 
Coal Technology'', up to a total amount of $2,500,000,000 for commercial 
demonstration of clean coal technology, or similar projects funded 
through appropriations for the Environmental Protection Agency. The 
Federal contribution for a qualifying project shall be at least 20 
percent of the total cost of the demonstration project.
    (35) Temporary clean coal technology demonstration project means a 
clean coal technology demonstration project that is operated for a 
period of 5 years or less, and which complies with the State 
implementation plan for the State in which the project is located and 
other requirements necessary to attain and maintain the national ambient 
air quality standards during and after the project is terminated.
    (36)(i) Repowering means replacement of an existing coal-fired 
boiler with one of the following clean coal technologies: atmospheric or 
pressurized fluidized bed combustion, integrated gasification combined 
cycle, magnetohydrodynamics, direct and indirect coal-fired turbines, 
integrated gasification fuel cells, or as determined by the 
Administrator, in consultation with the Secretary of Energy, a 
derivative of one or more of these technologies, and any other 
technology capable of controlling multiple combustion emissions 
simultaneously with improved boiler or generation efficiency and with 
significantly greater waste reduction relative to the performance of 
technology in widespread commercial use as of November 15, 1990.
    (ii) Repowering shall also include any oil and/or gas-fired unit 
which has been awarded clean coal technology demonstration funding as of 
January 1, 1991, by the Department of Energy.
    (iii) The reviewing authority shall give expedited consideration to 
permit applications for any source that satisfies the requirements of 
this subsection and is granted an extension under section 409 of the 
Clean Air Act.
    (37) Reactivation of a very clean coal-fired electric utility steam 
generating unit means any physical change or change in the method of 
operation associated with the commencement of commercial operations by a 
coal-fired utility unit after a period of discontinued operation where 
the unit:
    (i) Has not been in operation for the two-year period prior to the 
enactment of the Clean Air Act Amendments of 1990, and the emissions 
from such unit continue to be carried in the permitting authority's 
emissions inventory at the time of enactment;
    (ii) Was equipped prior to shutdown with a continuous system of 
emissions control that achieves a removal efficiency for sulfur dioxide 
of no less than 85 percent and a removal efficiency for particulates of 
no less than 98 percent;
    (iii) Is equipped with low-NOX burners prior to the time 
of commencement of operations following reactivation; and
    (iv) Is otherwise in compliance with the requirements of the Clean 
Air Act.
    (c) Ambient air increments. The plan shall contain emission 
limitations and such other measures as may be necessary to assure that 
in areas designated as Class I, II, or III, increases in pollutant 
concentration over the baseline concentration shall be limited to the 
following:

------------------------------------------------------------------------
                                                               Maximum
                                                              allowable
                                                               increase
                         Pollutant                           (micrograms
                                                              per cubic
                                                                meter)
------------------------------------------------------------------------
                                 Class I
------------------------------------------------------------------------
 
Particulate matter:
    PM-10, annual arithmetic mean..........................          4
    PM-10, 24-hr maximum...................................          8
Sulfur dioxide:
    Annual arithmetic mean.................................          2
    24-hr maximum..........................................          5
    3-hr maximum...........................................         25
Nitrogen dioxide: Annual arithmetic mean...................        2.5
 
------------------------------------------------------------------------
                                Class II
------------------------------------------------------------------------
 
Particulate matter:
    PM-10, annual arithmetic mean..........................         17
    PM-10, 24-hr maximum...................................         30
Sulfur dioxide:
    Annual arithmetic mean.................................         20
    24-hr maximum..........................................         91
    3-hr maximum...........................................        512

[[Page 176]]

 
Nitrogen dioxide:
    Annual arithmetic mean.................................         25
 
------------------------------------------------------------------------
                                Class III
 
------------------------------------------------------------------------
Particulate matter:
    PM-10, annual arithmetic mean..........................         34
    PM-10, 24-hr maximum...................................         60
Sulfur dioxide:
    Annual arithmetic mean.................................         40
    24-hr maximum..........................................        182
    3-hr maximum...........................................        700
Nitrogen dioxide: Annual arithmetic mean...................         50
------------------------------------------------------------------------


For any period other than an annual period, the applicable maximum 
allowable increase may be exceeded during one such period per year at 
any one location.
    (d) Ambient air ceilings. The plan shall provide that no 
concentration of a pollutant shall exceed:
    (1) The concentration permitted under the national secondary ambient 
air quality standard, or
    (2) The concentration permitted under the national primary ambient 
air quality standard, whichever concentration is lowest for the 
pollutant for a period of exposure.
    (e) Restrictions on area classifications. The plan shall provide 
that--
    (1) All of the following areas which were in existence on August 7, 
1977, shall be Class I areas and may not be redesignated:
    (i) International parks,
    (ii) National wilderness areas which exceed 5,000 acres in size,
    (iii) National memorial parks which exceed 5,000 acres in size, and
    (iv) National parks which exceed 6,000 acres in size.
    (2) Areas which were redesignated as Class I under regulations 
promulgated before August 7, 1977, shall remain Class I, but may be 
redesignated as provided in this section.
    (3) Any other area, unless otherwise specified in the legislation 
creating such an area, is initially designated Class II, but may be 
redesignated as provided in this section.
    (4) The following areas may be redesignated only as Class I or II:
    (i) An area which as of August 7, 1977, exceeded 10,000 acres in 
size and was a national monument, a national primitive area, a national 
preserve, a national recreational area, a national wild and scenic 
river, a national wildlife refuge, a national lakeshore or seashore; and
    (ii) A national park or national wilderness area established after 
August 7, 1977, which exceeds 10,000 acres in size.
    (f) Exclusions from increment consumption. (1) The plan may provide 
that the following concentrations shall be excluded in determining 
compliance with a maximum allowable increase:
    (i) Concentrations attributable to the increase in emissions from 
stationary sources which have converted from the use of petroleum 
products, natural gas, or both by reason of an order in effect under 
section 2 (a) and (b) of the Energy Supply and Environmental 
Coordination Act of 1974 (or any superseding legislation) over the 
emissions from such sources before the effective date of such an order;
    (ii) Concentrations attributable to the increase in emissions from 
sources which have converted from using natural gas by reason of natural 
gas curtailment plan in effect pursuant to the Federal Power Act over 
the emissions from such sources before the effective date of such plan;
    (iii) Concentrations of particulate matter attributable to the 
increase in emissions from construction or other temporary emission-
related activities of new or modified sources;
    (iv) The increase in concentrations attributable to new sources 
outside the United States over the concentrations attributable to 
existing sources which are included in the baseline concentration; and
    (v) Concentrations attributable to the temporary increase in 
emissions of sulfur dioxide, particulate matter, or nitrogen oxides from 
stationary sources which are affected by plan revisions approved by the 
Administrator as meeting the criteria specified in paragraph (f)(4) of 
this section.
    (2) If the plan provides that the concentrations to which paragraph 
(f)(1) (i) or (ii) of this section, refers shall be excluded, it shall 
also provide that no exclusion of such concentrations shall

[[Page 177]]

apply more than five years after the effective date of the order to 
which paragraph (f)(1)(i) of this section, refers or the plan to which 
paragraph (f)(1)(ii) of this section, refers, whichever is applicable. 
If both such order and plan are applicable, no such exclusion shall 
apply more than five years after the later of such effective dates.
    (3) [Reserved]
    (4) For purposes of excluding concentrations pursuant to paragraph 
(f)(1)(v) of this section, the Administrator may approve a plan revision 
that:
    (i) Specifies the time over which the temporary emissions increase 
of sulfur dioxide, particulate matter, or nitrogen oxides would occur. 
Such time is not to exceed 2 years in duration unless a longer time is 
approved by the Administrator.
    (ii) Specifies that the time period for excluding certain 
contributions in accordance with paragraph (f)(4)(i) of this section, is 
not renewable;
    (iii) Allows no emissions increase from a stationary source which 
would:
    (a) Impact a Class I area or an area where an applicable increment 
is known to be violated; or
    (b) Cause or contribute to the violation of a national ambient air 
quality standard;
    (iv) Requires limitations to be in effect the end of the time period 
specified in accordance with paragraph (f)(4)(i) of this section, which 
would ensure that the emissions levels from stationary sources affected 
by the plan revision would not exceed those levels occurring from such 
sources before the plan revision was approved.
    (g) Redesignation. (1) The plan shall provide that all areas of the 
State (except as otherwise provided under paragraph (e) of this section) 
shall be designated either Class I, Class II, or Class III. Any 
designation other than Class II shall be subject to the redesignation 
procedures of this paragraph. Redesignation (except as otherwise 
precluded by paragraph (e) of this section) may be proposed by the 
respective States or Indian Governing Bodies, as provided below, subject 
to approval by the Administrator as a revision to the applicable State 
implementation plan.
    (2) The plan may provide that the State may submit to the 
Administrator a proposal to redesignate areas of the State Class I or 
Class II: Provided, That:
    (i) At least one public hearing has been held in accordance with 
procedures established in Sec. 51.102.
    (ii) Other States, Indian Governing Bodies, and Federal Land 
Managers whose lands may be affected by the proposed redesignation were 
notified at least 30 days prior to the public hearing;
    (iii) A discussion of the reasons for the proposed redesignation, 
including a satisfactory description and analysis of the health, 
environmental, economic, social, and energy effects of the proposed 
redesignation, was prepared and made available for public inspection at 
least 30 days prior to the hearing and the notice announcing the hearing 
contained appropriate notification of the availability of such 
discussion;
    (iv) Prior to the issuance of notice respecting the redesignation of 
an area that includes any Federal lands, the State has provided written 
notice to the appropriate Federal Land Manager and afforded adequate 
opportunity (not in excess of 60 days) to confer with the State 
respecting the redesignation and to submit written comments and 
recommendations. In redesignating any area with respect to which any 
Federal Land Manager had submitted written comments and recommendations, 
the State shall have published a list of any inconsistency between such 
redesignation and such comments and recommendations (together with the 
reasons for making such redesignation against the recommendation of the 
Federal Land Manager); and
    (v) The State has proposed the redesignation after consultation with 
the elected leadership of local and other substate general purpose 
governments in the area covered by the proposed redesignation.
    (3) The plan may provide that any area other than an area to which 
paragraph (e) of this section refers may be redesignated as Class III 
if--
    (i) The redesignation would meet the requirements of provisions 
established in accordance with paragraph (g)(2) of this section;

[[Page 178]]

    (ii) The redesignation, except any established by an Indian 
Governing Body, has been specifically approved by the Governor of the 
State, after consultation with the appropriate committees of the 
legislature, if it is in session, or with the leadership of the 
legislature, if it is not in session (unless State law provides that 
such redesignation must be specifically approved by State legislation) 
and if general purpose units of local government representing a majority 
of the residents of the area to be redesignated enact legislation 
(including resolutions where appropriate) concurring in the 
redesignation;
    (iii) The redesignation would not cause, or contribute to, a 
concentration of any air pollutant which would exceed any maximum 
allowable increase permitted under the classification of any other area 
or any national ambient air quality standard; and
    (iv) Any permit application for any major stationary source or major 
modification subject to provisions established in accordance with 
paragraph (l) of this section which could receive a permit only if the 
area in question were redesignated as Class III, and any material 
submitted as part of that application, were available, insofar as was 
practicable, for public inspection prior to any public hearing on 
redesignation of any area as Class III.
    (4) The plan shall provide that lands within the exterior boundaries 
of Indian Reservations may be redesignated only by the appropriate 
Indian Governing Body. The appropriate Indian Governing Body may submit 
to the Administrator a proposal to redesignate areas Class I, Class II, 
or Class III: Provided, That:
    (i) The Indian Governing Body has followed procedures equivalent to 
those required of a State under paragraphs (g) (2), (3)(iii), and 
(3)(iv) of this section; and
    (ii) Such redesignation is proposed after consultation with the 
State(s) in which the Indian Reservation is located and which border the 
Indian Reservation.
    (5) The Administrator shall disapprove, within 90 days of 
submission, a proposed redesignation of any area only if he finds, after 
notice and opportunity for public hearing, that such redesignation does 
not meet the procedural requirements of this section or is inconsistent 
with paragraph (e) of this section. If any such disapproval occurs, the 
classification of the area shall be that which was in effect prior to 
the redesignation which was disapproved.
    (6) If the Administrator disapproves any proposed area designation, 
the State or Indian Governing Body, as appropriate, may resubmit the 
proposal after correcting the deficiencies noted by the Administrator.
    (h) Stack heights. The plan shall provide, as a minimum, that the 
degree of emission limitation required for control of any air pollutant 
under the plan shall not be affected in any manner by--
    (1) So much of a stack height, not in existence before December 31, 
1970, as exceeds good engineering practice, or
    (2) Any other dispersion technique not implemented before then.
    (i) Review of major stationary sources and major modifications--
source applicability and exemptions.
    (1) The plan shall provide that no major stationary source or major 
modification shall begin actual construction unless, as a minumum, 
requirements equivalent to those contained in paragraphs (j) through (r) 
of this section have been met.
    (2) The plan shall provide that the requirements equivalent to those 
contained in paragraphs (j) through (r) of this section shall apply to 
any major stationary source and any major modification with respect to 
each pollutant subject to regulation under the Act that it would emit, 
except as this section would otherwise allow.
    (3) The plan shall provide that requirements equivalent to those 
contained in paragraphs (j) through (r) of this section apply only to 
any major stationary source or major modification that would be 
constructed in an area which is designated as attainment or 
unclassifiable under section 107(a)(1) (D) or (E) of the Act; and
    (4) The plan may provide that requirements equivalent to those 
contained in paragraphs (j) through (r) of this section do not apply to 
a particular major stationary source or major modification if:

[[Page 179]]

    (i) The major stationary source would be a nonprofit health or 
nonprofit educational institution or a major modification that would 
occur at such an institution; or
    (ii) The source or modification would be a major stationary source 
or major modification only if fugitive emissions, to the extent 
quantifiable, are considered in calculating the potential to emit of the 
stationary source or modification and such source does not belong to any 
following categories:
    (a) Coal cleaning plants (with thermal dryers);
    (b) Kraft pulp mills;
    (c) Portland cement plants;
    (d) Primary zinc smelters;
    (e) Iron and steel mills;
    (f) Primary aluminum ore reduction plants;
    (g) Primary copper smelters;
    (h) Municipal incinerators capable of charging more than 250 tons of 
refuse per day;
    (i) Hydrofluoric, sulfuric, or nitric acid plants;
    (j) Petroleum refineries;
    (k) Lime plants;
    (l) Phosphate rock processing plants;
    (m) Coke oven batteries;
    (n) Sulfur recovery plants;
    (o) Carbon black plants (furnace process);
    (p) Primary lead smelters;
    (q) Fuel conversion plants;
    (r) Sintering plants;
    (s) Secondary metal production plants;
    (t) Chemical process plants;
    (u) Fossil-fuel boilers (or combination thereof) totaling more than 
250 million British thermal units per hour heat input;
    (v) Petroleum storage and transfer units with a total storage 
capacity exceeding 300,000 barrels;
    (w) Taconite ore processing plants;
    (x) Glass fiber processing plants;
    (y) Charcoal production plants;
    (z) Fossil fuel-fired steam electric plants of more than 250 million 
British thermal units per hour heat input;
    (aa) Any other stationary source category which, as of August 7, 
1980, is being regulated under section 111 or 112 of the Act; or
    (iii) The source or modification is a portable stationary source 
which has previously received a permit under requirements equivalent to 
those contained in paragraphs (j) through (r) of this section, if:
    (a) The source proposes to relocate and emissions of the source at 
the new location would be temporary; and
    (b) The emissions from the source would not exceed its allowable 
emissions; and
    (c) The emissions from the source would impact no Class I area and 
no area where an applicable increment is known to be violated; and
    (d) Reasonable notice is given to the reviewing authority prior to 
the relocation identifying the proposed new location and the probable 
duration of operation at the new location. Such notice shall be given to 
the reviewing authority not less than 10 days in advance of the proposed 
relocation unless a different time duration is previously approved by 
the reviewing authority.
    (5) The plan may provide that requirements equivalent to those 
contained in paragraphs (j) through (r) of this section do not apply to 
a major stationary source or major modification with respect to a 
particular pollutant if the owner or operator demonstrates that, as to 
that pollutant, the source or modification is located in an area 
designated as nonattainment under section 107 of the Act.
    (6) The plan may provide that requirements equivalent to those 
contained in paragraphs (k), (m), and (o) of this section do not apply 
to a proposed major stationary source or major modification with respect 
to a particular pollutant, if the allowable emissions of that pollutant 
from a new source, or the net emissions increase of that pollutant from 
a modification, would be temporary and impact no Class I area and no 
area where an applicable increment is known to be violated.
    (7) The plan may provide that requirements equivalent to those 
contained in paragraphs (k), (m), and (o) of this section as they relate 
to any maximum allowable increase for a Class II area do not apply to a 
modification of a major stationary source that was in existence on March 
1, 1978, if the net increase in allowable emissions of each pollutant 
subject to regulation under

[[Page 180]]

the Act from the modification after the application of best available 
control technology would be less than 50 tons per year.
    (8) The plan may provide that the reviewing authority may exempt a 
proposed major stationary source or major modification from the 
requirements of paragraph (m) of this section, with respect to 
monitoring for a particular pollutant, if:
    (i) The emissions increase of the pollutant from a new stationary 
source or the net emissions increase of the pollutant from a 
modification would cause, in any area, air quality impacts less than the 
following amounts:
    (a) Carbon monoxide--575 ug/m3, 8-hour average;
    (b) Nitrogen dioxide--14 ug/m3, annual average;
    (c) Particulate matter--10 g/m\3\ of PM-10, 24-hour 
average.
    (d) Sulfur dioxide--13 ug/m3, 24-hour average;
    (e) Ozone; 1
---------------------------------------------------------------------------

    1  No de minimis air quality level is provided for ozone. 
However, any net increase of 100 tons per year or more of volatile 
organic compounds subject to PSD would be required to perform and 
ambient impact analysis, including the gathering of ambient air quality 
data.
---------------------------------------------------------------------------

    (f) Lead--0.1 g/m\3\, 3-month average.
    (g) Mercury--0.25 ug/m3, 24-hour average;
    (h) Beryllium--0.001 g/m\3\, 24-hour average:
    (i) Fluorides--0.25 ug/m3, 24-hour average;
    (j) Vinyl chloride--15 ug/m3, 24-hour average;
    (k) Total reduced sulfur--10 ug/m3, 1-hour average;
    (l) Hydrogen sulfide--0.2 g/m\3\, 1-hour average:
    (m) Reduced sulfur compounds--10 ug/m3, 1-hour average; 
or
    (ii) The concentrations of the pollutant in the area that the source 
or modification would affect are less than the concentrations listed in 
(i)(8)(i) of this section; or
    (iii) The pollutants is not listed in paragraph (i)(8)(i) of this 
section.
    (9) If EPA approves a plan revision under 40 CFR 51.166 as in effect 
before August 7, 1980, any subsequent revision which meets the 
requirements of this section may contain transition provisions which 
parallel the transition provisions of 40 CFR 52.21(i)(9), (i)(10) and 
(m)(1)(v) as in effect on that date, which provisions relate to 
requirements for best available control technology and air quality 
analyses. Any such subsequent revision may not contain any transition 
provision which in the context of the revision would operate any less 
stringently than would its counterpart in 40 CFR 52.21.
    (10) If EPA approves a plan revision under Sec. 51.166 as in effect 
[before July 31, 1987], any subsequent revision which meets the 
requirements of this section may contain transition provisions which 
parallel the transition provisions of Sec. 52.21 (i)(11), and (m)(1) 
(vii) and (viii) of this chapter as in effect on that date, these 
provisions being related to monitoring requirements for particulate 
matter. Any such subsequent revision may not contain any transition 
provision which in the context of the revision would operate any less 
stringently than would its counterpart in Sec. 52.21 of this chapter.
    (11) The plan may provide that the permitting requirements 
equivalent to those contained in paragraph (k)(2) of this section do not 
apply to a stationary source or modification with respect to any maximum 
allowable increase for nitrogen oxides if the owner or operator of the 
source or modification submitted an application for a permit under the 
applicable permit program approved or promulgated under the Act before 
the provisions embodying the maximum allowable increase took effect as 
part of the plan and the permitting authority subsequently determined 
that the application as submitted before that date was complete.
    (12) The plan may provide that the permitting requirements 
equivalent to those contained in paragraph (k)(2) of this section shall 
not apply to a stationary source or modification with respect to any 
maximum allowable increase for PM-10 if (i) the owner or operator of the 
source or modification submitted an application for a permit under the 
applicable permit program approved under the Act before the provisions 
embodying the maximum allowable increases for PM-10 took effect

[[Page 181]]

as part of the plan, and (ii) the permitting authority subsequently 
determined that the application as submitted before that date was 
complete. Instead, the applicable requirements equivalent to paragraph 
(k)(2) shall apply with respect to the maximum allowable increases for 
TSP as in effect on the date the application was submitted.
    (j) Control technology review. The plan shall provide that:
    (1) A major stationary source or major modification shall meet each 
applicable emissions limitation under the State Implementation Plan and 
each applicable emission standards and standard of performance under 40 
CFR parts 60 and 61.
    (2) A new major stationary source shall apply best available control 
technology for each pollutant subject to regulation under the Act that 
it would have the potential to emit in significant amounts.
    (3) A major modification shall apply best available control 
technology for each pollutant subject to regulation under the Act for 
which it would be a significant net emissions increase at the source. 
This requirement applies to each proposed emissions unit at which a net 
emissions increase in the pollutant would occur as a result of a 
physical change or change in the method of operation in the unit.
    (4) For phased construction projects, the determination of best 
available control technology shall be reviewed and modified as 
appropriate at the least reasonable time which occurs no later than 18 
months prior to commencement of construction of each independent phase 
of the project. At such time, the owner or operator of the applicable 
stationary source may be required to demonstrate the adequacy of any 
previous determination of best available control technology for the 
source.
    (k) Source impact analysis. The plan shall provide that the owner or 
operator of the proposed source or modification shall demonstrate that 
allowable emission increases from the proposed source or modification, 
in conjunction with all other applicable emissions increases or 
reduction (including secondary emissions) would not cause or contribute 
to air pollution in violation of:
    (1) Any national ambient air quality standard in any air quality 
control region; or
    (2) Any applicable maximum allowable increase over the baseline 
concentration in any area.
    (l) Air quality models. The plan shall provide for procedures which 
specify that--
    (1) All applications of air quality modeling involved in this 
subpart shall be based on the applicable models, data bases, and other 
requirements specified in appendix W of this part (Guideline on Air 
Quality Models).
    (2) Where an air quality model specified in appendix W of this part 
(Guideline on Air Quality Models) is inappropriate, the model may be 
modified or another model substituted. Such a modification or 
substitution of a model may be made on a case-by-case basis or, where 
appropriate, on a generic basis for a specific State program. Written 
approval of the Administrator must be obtained for any modification or 
substitution. In addition, use of a modified or substituted model must 
be subject to notice and opportunity for public comment under procedures 
set forth in Sec. 51.102.
    (m) Air quality analysis--(1) Preapplication analysis. (i) The plan 
shall provide that any application for a permit under regulations 
approved pursuant to this section shall contain an analysis of ambient 
air quality in the area that the major stationary source or major 
modification would affect for each of the following pollutants:
    (a) For the source, each pollutant that it would have the potential 
to emit in a significant amount;
    (b) For the modification, each pollutant for which it would result 
in a significant net emissions increase.
    (ii) The plan shall provide that, with respect to any such pollutant 
for which no National Ambient Air Quality Standard exists, the analysis 
shall contain such air quality monitoring data as the reviewing 
authority determines is necessary to assess ambient air quality for that 
pollutant in any area that the emissions of that pollutant would affect.

[[Page 182]]

    (iii) The plan shall provide that with respect to any such pollutant 
(other than nonmethane hydrocarbons) for which such a standard does 
exist, the analysis shall contain continuous air quality monitoring data 
gathered for purposes of determining whether emissions of that pollutant 
would cause or contribute to a violation of the standard or any maxiumum 
allowable increase.
    (iv) The plan shall provide that, in general, the continuous air 
monitoring data that is required shall have been gathered over a period 
of one year and shall represent the year preceding receipt of the 
application, except that, if the reviewing authority determines that a 
complete and adequate analysis can be accomplished with monitoring data 
gathered over a period shorter than one year (but not to be less than 
four months), the data that is required shall have been gathered over at 
least that shorter period.
    (v) The plan may provide that the owner or operator of a proposed 
major stationary source or major modification of volatile organic 
compounds who satisfies all conditions of 40 CFR part 51 appendix S, 
section IV may provide postapproval monitoring data for ozone in lieu of 
providing preconstruction data as required under paragraph (m)(1) of 
this section.
    (2) Post-construction monitoring. The plan shall provide that the 
owner or operator of a major stationary source or major modification 
shall, after construction of the stationary source or modification, 
conduct such ambient monitoring as the reviewing authority determines is 
necessary to determine the effect emissions from the stationary source 
or modification may have, or are having, on air quality in any area.
    (3) Operation of monitoring stations. The plan shall provide that 
the owner or operator of a major stationary source or major modification 
shall meet the requirements of appendix B to part 58 of this chapter 
during the operation of monitoring stations for purposes of satisfying 
paragraph (m) of this section.
    (n) Source information. (1) The plan shall provide that the owner or 
operator of a proposed source or modification shall submit all 
information necessary to perform any analysis or make any determination 
required under procedures established in accordance with this section.
    (2) The plan may provide that such information shall include:
    (i) A description of the nature, location, design capacity, and 
typical operating schedule of the source or modification, including 
specifications and drawings showing its design and plant layout;
    (ii) A detailed schedule for construction of the source or 
modification;
    (iii) A detailed description as to what system of continuous 
emission reduction is planned by the source or modification, emission 
estimates, and any other information as necessary to determine that best 
available control technology as applicable would be applied;
    (3) The plan shall provide that upon request of the State, the owner 
or operator shall also provide information on:
    (i) The air quality impact of the source or modification, including 
meteorological and topographical data necessary to estimate such impact; 
and
    (ii) The air quality impacts and the nature and extent of any or all 
general commercial, residential, industrial, and other growth which has 
occurred since August 7, 1977, in the area the source or modification 
would affect.
    (o) Additional impact analyses. The plan shall provide that--
    (1) The owner or operator shall provide an analysis of the 
impairment to visibility, soils, and vegetation that would occur as a 
result of the source or modification and general commercial, 
residential, industrial, and other growth associated with the source or 
modification. The owner or operator need not provide an analysis of the 
impact on vegetation having no significant commercial or recreational 
value.
    (2) The owner or operator shall provide an analysis of the air 
quality impact projected for the area as a result of general commercial, 
residential, industrial, and other growth associated with the source or 
modification.
    (p) Sources impacting Federal Class I areas--additional 
requirements--(1) Notice to EPA. The plan shall provide that the 
reviewing authority shall transmit

[[Page 183]]

to the Administrator a copy of each permit application relating to a 
major stationary source or major modification and provide notice to the 
Administrator of every action related to the consideration of such 
permit.
    (2) Federal Land Manager. The Federal Land Manager and the Federal 
official charged with direct responsibility for management of Class I 
lands have an affirmative responsibility to protect the air quality 
related values (including visibility) of any such lands and to consider, 
in consultation with the Administrator, whether a proposed source or 
modification would have an adverse impact on such values.
    (3) Denial--impact on air quality related values. The plan shall 
provide a mechanism whereby a Federal Land Manager of any such lands may 
present to the State, after the reviewing authority's preliminary 
determination required under procedures developed in accordance with 
paragraph (r) of this section, a demonstration that the emissions from 
the proposed source or modification would have an adverse impact on the 
air quality-related values (including visibility) of any Federal 
mandatory Class I lands, notwithstanding that the change in air quality 
resulting from emissions from such source or modification would not 
cause or contribute to concentrations which would exceed the maximum 
allowable increases for a Class I area. If the State concurs with such 
demonstration, the reviewing authority shall not issue the permit.
    (4) Class I Variances. The plan may provide that the owner or 
operator of a proposed source or modification may demonstrate to the 
Federal Land Manager that the emissions from such source would have no 
adverse impact on the air quality related values of such lands 
(including visibility), notwithstanding that the change in air quality 
resulting from emissions from such source or modification would cause or 
contribute to concentrations which would exceed the maximum allowable 
increases for a Class I area. If the Federal land manager concurs with 
such demonstration and so certifies to the State, the reviewing 
authority may: Provided, That applicable requirements are otherwise met, 
issue the permit with such emission limitations as may be necessary to 
assure that emissions of sulfur dioxide, particulate matter, and 
nitrogen oxides would not exceed the following maximum allowable 
increases over minor source baseline concentration for such pollutants:

------------------------------------------------------------------------
                                                               Maximum
                                                              allowable
                                                               increase
                         Pollutant                           (micrograms
                                                              per cubic
                                                                meter)
------------------------------------------------------------------------
Particulate matter:
    PM-10, annual arithmetic mean..........................         17
    PM-10, 24-hour maximum.................................         30
Sulfur dioxide:
    Annual arithmetic mean.................................         20
    24-hr maximum..........................................         91
    3-hr maximum...........................................        325
Nitrogen dioxide: Annual arithmetic mean...................         25
------------------------------------------------------------------------

    (5) Sulfur dioxide variance by Governor with Federal Land Manager's 
concurrence. The plan may provide that--
    (i) The owner or operator of a proposed source or modification which 
cannot be approved under procedures developed pursuant to paragraph 
(q)(4) of this section may demonstrate to the Governor that the source 
or modification cannot be constructed by reason of any maximum allowable 
increase for sulfur dioxide for periods of twenty-four hours or less 
applicable to any Class I area and, in the case of Federal mandatory 
Class I areas, that a variance under this clause would not adversely 
affect the air quality related values of the area (including 
visibility);
    (ii) The Governor, after consideration of the Federal Land Manager's 
recommendation (if any) and subject to his concurrence, may grant, after 
notice and an opportunity for a public hearing, a variance from such 
maximum allowable increase; and
    (iii) If such variance is granted, the reviewing authority may issue 
a permit to such source or modification in accordance with provisions 
developed pursuant to paragraph (q)(7) of this section: Provided, That 
the applicable requirements of the plan are otherwise met.
    (6) Variance by the Governor with the President's concurrence. The 
plan may provide that--
    (i) The recommendations of the Governor and the Federal Land Manager 
shall be transferred to the President in

[[Page 184]]

any case where the Governor recommends a variance in which the Federal 
Land Manager does not concur;
    (ii) The President may approve the Governor's recommendation if he 
finds that such variance is in the national interest; and
    (iii) If such a variance is approved, the reviewing authority may 
issue a permit in accordance with provisions developed pursuant to the 
requirements of paragraph (q)(7) of this section: Provided, That the 
applicable requirements of the plan are otherwise met.
    (7) Emission limitations for Presidential or gubernatorial variance. 
The plan shall provide that in the case of a permit issued under 
procedures developed pursuant to paragraph (q) (5) or (6) of this 
section, the source or modification shall comply with emission 
limitations as may be necessary to assure that emissions of sulfur 
dioxide from the source or modification would not (during any day on 
which the otherwise applicable maximum allowable increases are exceeded) 
cause or contribute to concentrations which would exceed the following 
maximum allowable increases over the baseline concentration and to 
assure that such emissions would not cause or contribute to 
concentrations which exceed the otherwise applicable maximum allowable 
increases for periods of exposure of 24 hours or less for more than 18 
days, not necessarily consecutive, during any annual period:

                       Maximum Allowable Increase
                      [Micrograms per cubic meter]
------------------------------------------------------------------------
                                                          Terrain areas
                  Period of exposure                   -----------------
                                                          Low      High
------------------------------------------------------------------------
24-hr maximum.........................................       36       62
3-hr maximum..........................................      130      221
------------------------------------------------------------------------

    (q) Public participation. The plan shall provide that--
    (1) The reviewing authority shall notify all applicants within a 
specified time period as to the completeness of the application or any 
deficiency in the application or information submitted. In the event of 
such a deficiency, the date of receipt of the application shall be the 
date on which the reviewing authority received all required information.
    (2) Within one year after receipt of a complete application, the 
reviewing authority shall:
    (i) Make a preliminary determination whether construction should be 
approved, approved with conditions, or disapproved.
    (ii) Make available in at least one location in each region in which 
the proposed source would be constructed a copy of all materials the 
applicant submitted, a copy of the preliminary determination, and a copy 
or summary of other materials, if any, considered in making the 
preliminary determination.
    (iii) Notify the public, by advertisement in a newspaper of general 
circulation in each region in which the proposed source would be 
constructed, of the application, the preliminary determination, the 
degree of increment consumption that is expected from the source or 
modification, and of the opportunity for comment at a public hearing as 
well as written public comment.
    (iv) Send a copy of the notice of public comment to the applicant, 
the Administrator and to officials and agencies having cognizance over 
the location where the proposed construction would occur as follows: Any 
other State or local air pollution control agencies, the chief 
executives of the city and county where the source would be located; any 
comprehensive regional land use planning agency, and any State, Federal 
Land Manager, or Indian Governing body whose lands may be affected by 
emissions from the source or modification.
    (v) Provide opportunity for a public hearing for interested persons 
to appear and submit written or oral comments on the air quality impact 
of the source, alternatives to it, the control technology required, and 
other appropriate considerations.
    (vi) Consider all written comments submitted within a time specified 
in the notice of public comment and all comments received at any public 
hearing(s) in making a final decision on the approvability of the 
application. The reviewing authority shall make all

[[Page 185]]

comments available for public inspection in the same locations where the 
reviewing authority made available preconstruction information relating 
to the proposed source or modification.
    (vii) Make a final determination whether construction should be 
approved, approved with conditions, or disapproved.
    (viii) Notify the applicant in writing of the final determination 
and make such notification available for public inspection at the same 
location where the reviewing authority made available preconstruction 
information and public comments relating to the source.
    (r) Source obligation. (1) The plan shall include enforceable 
procedures to provide that approval to construct shall not relieve any 
owner or operator of the responsibility to comply fully with applicable 
provisions of the plan and any other requirements under local, State or 
Federal law.
    (2) The plan shall provide that at such time that a particular 
source or modification becomes a major stationary source or major 
modification solely by virtue of a relaxation in any enforceable 
limitation which was established after August 7, 1980, on the capacity 
of the source or modification otherwise to emit a pollutant, such as a 
restriction on hours of operation, then the requirements of paragraphs 
(j) through (s) of this section shall apply to the source or 
modification as though construction had not yet commenced on the source 
or modification.
    (s) Innovative control technology. (1) The plan may provide that an 
owner or operator of a proposed major stationary source or major 
modification may request the reviewing authority to approve a system of 
innovative control technology.
    (2) The plan may provide that the reviewing authority may, with the 
consent of the Governor(s) of other affected State(s), determine that 
the source or modification may employ a system of innovative control 
technology, if:
    (i) The proposed control system would not cause or contribute to an 
unreasonable risk to public health, welfare, or safety in its operation 
or function;
    (ii) The owner or operator agrees to achieve a level of continuous 
emissions reduction equivalent to that which would have been required 
under paragraph (j)(2) of this section, by a date specified by the 
reviewing authority. Such date shall not be later than 4 years from the 
time of startup or 7 years from permit issuance;
    (iii) The source or modification would meet the requirements 
equivalent to those in paragraphs (j) and (k) of this section, based on 
the emissions rate that the stationary source employing the system of 
innovative control technology would be required to meet on the date 
specified by the reviewing authority;
    (iv) The source or modification would not before the date specified 
by the reviewing authority:
    (a) Cause or contribute to any violation of an applicable national 
ambient air quality standard; or
    (b) Impact any area where an applicable increment is known to be 
violated;
    (v) All other applicable requirements including those for public 
participation have been met.
    (vi) The provisions of paragraph (p) of this section (relating to 
Class I areas) have been satisfied with respect to all periods during 
the life of the source or modification.
    (3) The plan shall provide that the reviewing authority shall 
withdraw any approval to employ a system of innovative control 
technology made under this section, if:
    (i) The proposed system fails by the specified date to achieve the 
required continuous emissions reduction rate; or
    (ii) The proposed system fails before the specified date so as to 
contribute to an unreasonable risk to public health, welfare, or safety; 
or
    (iii) The reviewing authority decides at any time that the proposed 
system is unlikely to achieve the required level of control or to 
protect the public health, welfare, or safety.
    (4) The plan may provide that if a source or modification fails to 
meet the required level of continuous emissions reduction within the 
specified time period, or if the approval is withdrawn in accordance 
with paragraph

[[Page 186]]

(s)(3) of this section, the reviewing authority may allow the source or 
modification up to an additional 3 years to meet the requirement for the 
application of best available control technology through use of a 
demonstrated system of control.

(Secs. 101(b)(1), 110, 160-169, 171-178, and 301(a), Clean Air Act, as 
amended (42 U.S.C. 7401(b)(1), 7410, 7470-7479, 7501-7508, and 7601(a)); 
sec. 129(a), Clean Air Act Amendments of 1977 (Pub. L. 95-95, 91 Stat. 
685 (Aug. 7, 1977)))

[43 FR 26382, June 19, 1978]

    Editorial Note: For Federal Register citations affecting 
Sec. 51.166, see the List of CFR Sections Affected in the Finding Aids 
section of this volume.



               Subpart J--Ambient Air Quality Surveillance

    Authority: Secs. 110, 301(a), 313, 319, Clean Air Act (42 U.S.C. 
7410, 7601(a), 7613, 7619).



Sec. 51.190  Ambient air quality monitoring requirements.

    The requirements for monitoring ambient air quality for purposes of 
the plan are located in subpart C of part 58 of this chapter.

[44 FR 27569, May 10, 1979]



                     Subpart K--Source Survelliance

    Source: 51 FR 40673, Nov. 7, 1986, unless otherwise noted.



Sec. 51.210  General.

    Each plan must provide for monitoring the status of compliance with 
any rules and regulations that set forth any portion of the control 
strategy. Specifically, the plan must meet the requirements of this 
subpart.



Sec. 51.211  Emission reports and recordkeeping.

    The plan must provide for legally enforceable procedures for 
requiring owners or operators of stationary sources to maintain records 
of and periodically report to the State--
    (a) Information on the nature and amount of emissions from the 
stationary sources; and
    (b) Other information as may be necessary to enable the State to 
determine whether the sources are in compliance with applicable portions 
of the control strategy.



Sec. 51.212  Testing, inspection, enforcement, and complaints.

    The plan must provide for--
    (a) Periodic testing and inspection of stationary sources; and
    (b) Establishment of a system for detecting violations of any rules 
and regulations through the enforcement of appropriate visible emission 
limitations and for investigating complaints.
    (c) Enforceable test methods for each emission limit specified in 
the plan. For the purpose of submitting compliance certifications or 
establishing whether or not a person has violated or is in violation of 
any standard in this part, the plan must not preclude the use, including 
the exclusive use, of any credible evidence or information, relevant to 
whether a source would have been in compliance with applicable 
requirements if the appropriate performance or compliance test or 
procedure had been performed. As an enforceable method, States may use:
    (1) Any of the appropriate methods in appendix M to this part, 
Recommended Test Methods for State Implementation Plans; or
    (2) An alternative method following review and approval of that 
method by the Administrator; or
    (3) Any appropriate method in appendix A to 40 CFR part 60.

[51 FR 40673, Nov. 7, 1986, as amended at 55 FR 14249, Apr. 17, 1990; 62 
FR 8328, Feb. 24, 1997]



Sec. 51.213  Transportation control measures.

    (a) The plan must contain procedures for obtaining and maintaining 
data on actual emissions reductions achieved as a result of implementing 
transportation control measures.
    (b) In the case of measures based on traffic flow changes or 
reductions in vehicle use, the data must include observed changes in 
vehicle miles traveled and average speeds.
    (c) The data must be maintained in such a way as to facilitate 
comparison of the planned and actual efficacy of the transportation 
control measures.

[61 FR 30163, June 14, 1996]

[[Page 187]]



Sec. 51.214  Continuous emission monitoring.

    (a) The plan must contain legally enforceable procedures to--
    (1) Require stationary sources subject to emission standards as part 
of an applicable plan to install, calibrate, maintain, and operate 
equipment for continuously monitoring and recording emissions; and
    (2) Provide other information as specified in appendix P of this 
part.
    (b) The procedures must--
    (1) Identify the types of sources, by source category and capacity, 
that must install the equipment; and
    (2) Identify for each source category the pollutants which must be 
monitored.
    (c) The procedures must, as a minimum, require the types of sources 
set forth in appendix P of this part to meet the applicable requirements 
set forth therein.
    (d)(1) The procedures must contain provisions that require the owner 
or operator of each source subject to continuous emission monitoring and 
recording requirements to maintain a file of all pertinent information 
for at least two years following the date of collection of that 
information.
    (2) The information must include emission measurements, continuous 
monitoring system performance testing measurements, performance 
evaluations, calibration checks, and adjustments and maintenance 
performed on such monitoring systems and other reports and records 
required by appendix P of this part.
    (e) The procedures must require the source owner or operator to 
submit information relating to emissions and operation of the emission 
monitors to the State to the extent described in appendix P at least as 
frequently as described therein.
    (f)(1) The procedures must provide that sources subject to the 
requirements of paragraph (c) of this section must have installed all 
necessary equipment and shall have begun monitoring and recording within 
18 months after either--
    (i) The approval of a State plan requiring monitoring for that 
source; or
    (ii) Promulgation by the Agency of monitoring requirements for that 
source.
    (2) The State may grant reasonable extensions of this period to 
sources that--
    (i) Have made good faith efforts to purchases, install, and begin 
the monitoring and recording of emission data; and
    (ii) Have been unable to complete the installation within the 
period.



                       Subpart L--Legal Authority

    Source: 51 FR 40673, Nov. 7, 1986, unless otherwise noted.



Sec. 51.230  Requirements for all plans.

    Each plan must show that the State has legal authority to carry out 
the plan, including authority to:
    (a) Adopt emission standards and limitations and any other measures 
necessary for attainment and maintenance of national standards.
    (b) Enforce applicable laws, regulations, and standards, and seek 
injunctive relief.
    (c) Abate pollutant emissions on an emergency basis to prevent 
substantial endangerment to the health of persons, i.e., authority 
comparable to that available to the Administrator under section 305 of 
the Act.
    (d) Prevent construction, modification, or operation of a facility, 
building, structure, or installation, or combination thereof, which 
directly or indirectly results or may result in emissions of any air 
pollutant at any location which will prevent the attainment or 
maintenance of a national standard.
    (e) Obtain information necessary to determine whether air pollution 
sources are in compliance with applicable laws, regulations, and 
standards, including authority to require recordkeeping and to make 
inspections and conduct tests of air pollution sources.
    (f) Require owners or operators of stationary sources to install, 
maintain, and use emission monitoring devices and to make periodic 
reports to the State on the nature and amounts of emissions from such 
stationary sources; also authority for the State to make such data 
available to the public as reported and as correlated with any

[[Page 188]]

applicable emission standards or limitations.



Sec. 51.231  Identification of legal authority.

    (a) The provisions of law or regulation which the State determines 
provide the authorities required under this section must be specifically 
identified, and copies of such laws or regulations be submitted with the 
plan.
    (b) The plan must show that the legal authorities specified in this 
subpart are available to the State at the time of submission of the 
plan.
    (c) Legal authority adequate to fulfill the requirements of 
Sec. 51.230 (e) and (f) of this subpart may be delegated to the State 
under section 114 of the Act.



Sec. 51.232  Assignment of legal authority to local agencies.

    (a) A State government agency other than the State air pollution 
control agency may be assigned responsibility for carrying out a portion 
of a plan if the plan demonstrates to the Administrator's satisfaction 
that the State governmental agency has the legal authority necessary to 
carry out the portion of plan.
    (b) The State may authorize a local agency to carry out a plan, or 
portion thereof, within such local agency's jurisdiction if--
    (1) The plan demonstrates to the Administrator's satisfaction that 
the local agency has the legal authority necessary to implement the plan 
or portion of it; and
    (2) This authorization does not relieve the State of responsibility 
under the Act for carrying out such plan, or portion thereof.



                Subpart M--Intergovernmental Consultation

    Authority: Secs. 110, 121, 174(a), 301(a), Clean Air Act, as amended 
(42 U.S.C. 7410, 7421, 7504, and 7601(a)).

    Source: 44 FR 35179, June 18, 1979, unless otherwise noted.

                           Agency Designation



Sec. 51.240  General plan requirements.

    Each State implementation plan must identify organizations, by 
official title, that will participate in developing, implementing, and 
enforcing the plan and the responsibilities of such organizations. The 
plan shall include any related agreements or memoranda of understanding 
among the organizations.



Sec. 51.241  Nonattainment areas for carbon monoxide and ozone.

    (a) For each AQCR or portion of an AQCR in which the national 
primary standard for carbon monoxide or ozone will not be attained by 
July 1, 1979, the Governor (or Governors for interstate areas) shall 
certify, after consultation with local officials, the organization 
responsible for developing the revised implementation plan or portions 
thereof for such AQCR.
    (b)-(f) [Reserved]

[44 FR 35179, June 18, 1979, as amended at 48 FR 29302, June 24, 1983; 
60 FR 33922, June 29, 1995; 61 FR 16060, Apr. 11, 1996]



Sec. 51.242  [Reserved]



                     Subpart N--Compliance Schedules

    Source: 51 FR 40673, Nov. 7, 1986, unless otherwise noted.



Sec. 51.260  Legally enforceable compliance schedules.

    (a) Each plan shall contain legally enforceable compliance schedules 
setting forth the dates by which all stationary and mobile sources or 
categories of such sources must be in compliance with any applicable 
requirement of the plan.
    (b) The compliance schedules must contain increments of progress 
required by Sec. 51.262 of this subpart.



Sec. 51.261  Final compliance schedules.

    (a) Unless EPA grants an extension under subpart R, compliance 
schedules designed to provide for attainment of a primary standard 
must--
    (1) Provide for compliance with the applicable plan requirements as 
soon as practicable; or
    (2) Provide for compliance no later than the date specified for 
attainment of the primary standard under;
    (b) Unless EPA grants an extension under subpart R, compliance 
schedules

[[Page 189]]

designed to provide for attainment of a secondary standard must--
    (1) Provide for compliance with the applicable plan requirements in 
a reasonable time; or
    (2) Provide for compliance no later than the date specified for the 
attainment of the secondary standard under Sec. 51.110(c).



Sec. 51.262  Extension beyond one year.

    (a) Any compliance schedule or revision of it extending over a 
period of more than one year from the date of its adoption by the State 
agency must provide for legally enforceable increments of progress 
toward compliance by each affected source or category of sources. The 
increments of progress must include--
    (1) Each increment of progress specified in Sec. 51.100(q); and
    (2) Additional increments of progress as may be necessary to permit 
close and effective supervision of progress toward timely compliance.
    (b) [Reserved]



           Subpart O--Miscellaneous Plan Content Requirements

    Authority: Secs. 110, 301(a), 313, 319, Clean Air Act (42 U.S.C. 
7410, 7601(a), 7613, 7619).



Sec. 51.280  Resources.

    Each plan must include a description of the resources available to 
the State and local agencies at the date of submission of the plan and 
of any additional resources needed to carry out the plan during the 5-
year period following its submission. The description must include 
projections of the extent to which resources will be acquired at 1-, 3-, 
and 5-year intervals.

[51 FR 40674, Nov. 7, 1986]



Sec. 51.281  Copies of rules and regulations.

    Emission limitations and other measures necessary for attainment and 
maintenance of any national standard, including any measures necessary 
to implement the requirements of subpart L must be adopted as rules and 
regulations enforceable by the State agency. Copies of all such rules 
and regulations must be submitted with the plan. Submittal of a plan 
setting forth proposed rules and regulations will not satisfy the 
requirements of this section nor will it be considered a timely 
submittal.

[51 FR 40674, Nov. 7, 1986]



Sec. 51.285  Public notification.

    By March 1, 1980, the State shall submit a plan revision that 
contains provisions for:
    (a) Notifying the public on a regular basis of instances or areas in 
which any primary standard was exceeded during any portion of the 
preceeding calendar year,
    (b) Advising the public of the health hazards associated with such 
an exceedance of a primary standard, and
    (c) Increasing public awareness of:
    (1) Measures which can be taken to prevent a primary standard from 
being exceeded, and
    (2) Ways in which the public can participate in regulatory and other 
efforts to improve air quality.

[44 FR 27569, May 10, 1979]



                   Subpart P--Protection of Visibility

    Authority: Secs. 110, 114, 121, 160-169, 169A, and 301 of the Clean 
Air Act, (42 U.S.C. 7410, 7414, 7421, 7470-7479, and 7601).

    Source: 45 FR 80089, Dec. 2, 1980, unless otherwise noted.



Sec. 51.300  Purpose and applicability.

    (a) Purpose. The primary purposes of this subpart are to require 
States to develop programs to assure reasonable progress toward meeting 
the national goal of preventing any future, and remedying any existing, 
impairment of visibility in mandatory Class I Federal areas which 
impairment results from manmade air pollution; and to establish 
necessary additional procedures for new source permit applicants, States 
and Federal Land Managers to use in conducting the visibility impact 
analysis required for new sources under Sec. 51.166. This subpart sets 
forth requirements addressing visibility impairment in its two principal 
forms: ``reasonably attributable'' impairment (i.e., impairment 
attributable to a single source/small group of sources) and regional

[[Page 190]]

haze (i.e., widespread haze from a multitude of sources which impairs 
visibility in every direction over a large area).
    (b) Applicability. (1) General Applicability. The provisions of this 
subpart pertaining to implementation plan requirements for assuring 
reasonable progress in preventing any future and remedying any existing 
visibility impairment are applicable to:
    (i) Each State which has a mandatory Class I Federal area identified 
in part 81, subpart D, of this title, and (ii) each State in which there 
is any source the emissions from which may reasonably be anticipated to 
cause or contribute to any impairment of visibility in any such area.
    (2) The provisions of this subpart pertaining to implementation 
plans to address reasonably attributable visibility impairment are 
applicable to the following States:

  Alabama, Alaska, Arizona, Arkansas, California, Colorado, Florida, 
    Georgia, Hawaii, Idaho, Kentucky, Louisiana, Maine, Michigan, 
    Minnesota, Missouri, Montana, Nevada, New Hampshire, New Jersey, New 
    Mexico, North Carolina, North Dakota, Oklahoma, Oregon, South 
    Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, 
    Virgin Islands, Washington, West Virginia, Wyoming.

    (3) The provisions of this subpart pertaining to implementation 
plans to address regional haze visibility impairment are applicable to 
all States as defined in section 302(d) of the Clean Air Act (CAA) 
except Guam, Puerto Rico, American Samoa, and the Northern Mariana 
Islands.

[45 FR 80089, Dec. 2, 1980, as amended at 64 FR 35763, July 1, 1999]



Sec. 51.301  Definitions.

    For purposes of this subpart:
    Adverse impact on visibility means, for purposes of section 307, 
visibility impairment which interferes with the management, protection, 
preservation, or enjoyment of the visitor's visual experience of the 
Federal Class I area. This determination must be made on a case-by-case 
basis taking into account the geographic extent, intensity, duration, 
frequency and time of visibility impairments, and how these factors 
correlate with (1) times of visitor use of the Federal Class I area, and 
(2) the frequency and timing of natural conditions that reduce 
visibility. This term does not include effects on integral vistas.
    Agency means the U.S. Environmental Protection Agency.
    BART-eligible source means an existing stationary facility as 
defined in this section.
    Best Available Retrofit Technology (BART) means an emission 
limitation based on the degree of reduction achievable through the 
application of the best system of continuous emission reduction for each 
pollutant which is emitted by an existing stationary facility. The 
emission limitation must be established, on a case-by-case basis, taking 
into consideration the technology available, the costs of compliance, 
the energy and nonair quality environmental impacts of compliance, any 
pollution control equipment in use or in existence at the source, the 
remaining useful life of the source, and the degree of improvement in 
visibility which may reasonably be anticipated to result from the use of 
such technology.
    Building, structure, or facility means all of the pollutant-emitting 
activities which belong to the same industrial grouping, are located on 
one or more contiguous or adjacent properties, and are under the control 
of the same person (or persons under common control). Pollutant-emitting 
activities must be considered as part of the same industrial grouping if 
they belong to the same Major Group (i.e., which have the same two-digit 
code) as described in the Standard Industrial Classification Manual, 
1972 as amended by the 1977 Supplement (U.S. Government Printing Office 
stock numbers 4101-0066 and 003-005-00176-0 respectively).
    Deciview means a measurement of visibility impairment. A deciview is 
a haze index derived from calculated light extinction, such that uniform 
changes in haziness correspond to uniform incremental changes in 
perception across the entire range of conditions, from pristine to 
highly impaired. The deciview haze index is calculated

[[Page 191]]

based on the following equation (for the purposes of calculating 
deciview, the atmospheric light extinction coefficient must be 
calculated from aerosol measurements):

Deciview haze index=10 lne (bext/10 
    Mm-1).
Where bext=the atmospheric light extinction coefficient, 
    expressed in inverse megameters (Mm-1).

    Existing stationary facility means any of the following stationary 
sources of air pollutants, including any reconstructed source, which was 
not in operation prior to August 7, 1962, and was in existence on August 
7, 1977, and has the potential to emit 250 tons per year or more of any 
air pollutant. In determining potential to emit, fugitive emissions, to 
the extent quantifiable, must be counted.
    Fossil-fuel fired steam electric plants of more than 250 million 
British thermal units per hour heat input,
    Coal cleaning plants (thermal dryers),
    Kraft pulp mills,
    Portland cement plants,
    Primary zinc smelters,
    Iron and steel mill plants,
    Primary aluminum ore reduction plants,
    Primary copper smelters,
    Municipal incinerators capable of charging more than 250 tons of 
refuse per day,
    Hydrofluoric, sulfuric, and nitric acid plants,
    Petroleum refineries,
    Lime plants,
    Phosphate rock processing plants,
    Coke oven batteries,
    Sulfur recovery plants,
    Carbon black plants (furnace process),
    Primary lead smelters,
    Fuel conversion plants,
    Sintering plants,
    Secondary metal production facilities,
    Chemical process plants,
    Fossil-fuel boilers of more than 250 million British thermal units 
per hour heat input,
    Petroleum storage and transfer facilities with a capacity exceeding 
300,000 barrels,
    Taconite ore processing facilities,
    Glass fiber processing plants, and
    Charcoal production facilities.
    Federal Class I area means any Federal land that is classified or 
reclassified Class I.
    Federal Land Manager means the Secretary of the department with 
authority over the Federal Class I area (or the Secretary's designee) 
or, with respect to Roosevelt-Campobello International Park, the 
Chairman of the Roosevelt-Campobello International Park Commission.
    Federally enforceable means all limitations and conditions which are 
enforceable by the Administrator under the Clean Air Act including those 
requirements developed pursuant to parts 60 and 61 of this title, 
requirements within any applicable State Implementation Plan, and any 
permit requirements established pursuant to Sec. 52.21 of this chapter 
or under regulations approved pursuant to part 51, 52, or 60 of this 
title.
    Fixed capital cost means the capital needed to provide all of the 
depreciable components.
    Fugitive Emissions means those emissions which could not reasonably 
pass through a stack, chimney, vent, or other functionally equivalent 
opening.
    Geographic enhancement for the purpose of Sec. 51.308 means a 
method, procedure, or process to allow a broad regional strategy, such 
as an emissions trading program designed to achieve greater reasonable 
progress than BART for regional haze, to accommodate BART for reasonably 
attributable impairment.
    Implementation plan means, for the purposes of this part, any State 
Implementation Plan, Federal Implementation Plan, or Tribal 
Implementation Plan.
    Indian tribe or tribe means any Indian tribe, band, nation, or other 
organized group or community, including any Alaska Native village, which 
is federally recognized as eligible for the special programs and 
services provided by the United States to Indians because of their 
status as Indians.
    In existence means that the owner or operator has obtained all 
necessary preconstruction approvals or permits required by Federal, 
State, or local air pollution emissions and air quality laws or 
regulations and either has (1)

[[Page 192]]

begun, or caused to begin, a continuous program of physical on-site 
construction of the facility or (2) entered into binding agreements or 
contractual obligations, which cannot be cancelled or modified without 
substantial loss to the owner or operator, to undertake a program of 
construction of the facility to be completed in a reasonable time.
    In operation means engaged in activity related to the primary design 
function of the source.
    Installation means an identifiable piece of process equipment.
    Integral vista means a view perceived from within the mandatory 
Class I Federal area of a specific landmark or panorama located outside 
the boundary of the mandatory Class I Federal area.
    Least impaired days means the average visibility impairment 
(measured in deciviews) for the twenty percent of monitored days in a 
calendar year with the lowest amount of visibility impairment.
    Major stationary source and major modification mean major stationary 
source and major modification, respectively, as defined in Sec. 51.166.
    Mandatory Class I Federal Area means any area identified in part 81, 
subpart D of this title.
    Most impaired days means the average visibility impairment (measured 
in deciviews) for the twenty percent of monitored days in a calendar 
year with the highest amount of visibility impairment.
    Natural conditions includes naturally occurring phenomena that 
reduce visibility as measured in terms of light extinction, visual 
range, contrast, or coloration.
    Potential to emit means the maximum capacity of a stationary source 
to emit a pollutant under its physical and operational design. Any 
physical or operational limitation on the capacity of the source to emit 
a pollutant including air pollution control equipment and restrictions 
on hours of operation or on the type or amount of material combusted, 
stored, or processed, shall be treated as part of its design if the 
limitation or the effect it would have on emissions is federally 
enforceable. Secondary emissions do not count in determining the 
potential to emit of a stationary source.
    Reasonably attributable means attributable by visual observation or 
any other technique the State deems appropriate.
    Reasonably attributable visibility impairment means visibility 
impairment that is caused by the emission of air pollutants from one, or 
a small number of sources.
    Reconstruction will be presumed to have taken place where the fixed 
capital cost of the new component exceeds 50 percent of the fixed 
capital cost of a comparable entirely new source. Any final decision as 
to whether reconstruction has occurred must be made in accordance with 
the provisions of Sec. 60.15 (f) (1) through (3) of this title.
    Regional haze means visibility impairment that is caused by the 
emission of air pollutants from numerous sources located over a wide 
geographic area. Such sources include, but are not limited to, major and 
minor stationary sources, mobile sources, and area sources.
    Secondary emissions means emissions which occur as a result of the 
construction or operation of an existing stationary facility but do not 
come from the existing stationary facility. Secondary emissions may 
include, but are not limited to, emissions from ships or trains coming 
to or from the existing stationary facility.
    Significant impairment means, for purposes of Sec. 51.303, 
visibility impairment which, in the judgment of the Administrator, 
interferes with the management, protection, preservation, or enjoyment 
of the visitor's visual experience of the mandatory Class I Federal 
area. This determination must be made on a case-by-case basis taking 
into account the geographic extent, intensity, duration, frequency and 
time of the visibility impairment, and how these factors correlate with 
(1) times of visitor use of the mandatory Class I Federal area, and (2) 
the frequency and timing of natural conditions that reduce visibility.
    State means ``State'' as defined in section 302(d) of the CAA.
    Stationary Source means any building, structure, facility, or 
installation which emits or may emit any air pollutant.

[[Page 193]]

    Visibility impairment means any humanly perceptible change in 
visibility (light extinction, visual range, contrast, coloration) from 
that which would have existed under natural conditions.
    Visibility in any mandatory Class I Federal area includes any 
integral vista associated with that area.

[45 FR 80089, Dec. 2, 1980, as amended at 64 FR 35763, 35774, July 1, 
1999]



Sec. 51.302  Implementation control strategies for reasonably attributable visibility impairment.

    (a) Plan Revision Procedures. (1) Each State identified in 
Sec. 51.300(b)(2) must have submitted, not later than September 2, 1981, 
an implementation plan meeting the requirements of this subpart 
pertaining to reasonably attributable visibility impairment.
    (2)(i) The State, prior to adoption of any implementation plan to 
address reasonably attributable visibility impairment required by this 
subpart, must conduct one or more public hearings on such plan in 
accordance with Sec. 51.102.
    (ii) In addition to the requirements in Sec. 51.102, the State must 
provide written notification of such hearings to each affected Federal 
Land Manager, and other affected States, and must state where the public 
can inspect a summary prepared by the Federal Land Managers of their 
conclusions and recommendations, if any, on the proposed plan revision.
    (3) Submission of plans as required by this subpart must be 
conducted in accordance with the procedures in Sec. 51.103.
    (b) State and Federal Land Manager Coordination. (1) The State must 
identify to the Federal Land Managers, in writing and within 30 days of 
the date of promulgation of these regulations, the title of the official 
to which the Federal Land Manager of any mandatory Class I Federal area 
can submit a recommendation on the implementation of this subpart 
including, but not limited to:
    (i) A list of integral vistas that are to be listed by the State for 
the purpose of implementing section 304,
    (ii) Identification of impairment of visibility in any mandatory 
Class I Federal area(s), and
    (iii) Identification of elements for inclusion in the visibility 
monitoring strategy required by section 305.
    (2) The State must provide opportunity for consultation, in person 
and at least 60 days prior to holding any public hearing on the plan, 
with the Federal Land Manager on the proposed SIP revision required by 
this subpart. This consultation must include the opportunity for the 
affected Federal Land Managers to discuss their:
    (i) Assessment of impairment of visibility in any mandatory Class I 
Federal area, and
    (ii) Recommendations on the development of the long-term strategy.
    (3) The plan must provide procedures for continuing consultation 
between the State and Federal Land Manager on the implementation of the 
visibility protection program required by this subpart.
    (c) General plan requirements for reasonably attributable visibility 
impairment. (1) The affected Federal Land Manager may certify to the 
State, at any time, that there exists reasonably attributable impairment 
of visibility in any mandatory Class I Federal area.
    (2) The plan must contain the following to address reasonably 
attributable impairment:
    (i) A long-term (10-15 years) strategy, as specified in Sec. 51.305 
and Sec. 51.306, including such emission limitations, schedules of 
compliance, and such other measures including schedules for the 
implementation of the elements of the long-term strategy as may be 
necessary to make reasonable progress toward the national goal specified 
in Sec. 51.300(a).
    (ii) An assessment of visibility impairment and a discussion of how 
each element of the plan relates to the preventing of future or 
remedying of existing impairment of visibility in any mandatory Class I 
Federal area within the State.
    (iii) Emission limitations representing BART and schedules for 
compliance with BART for each existing stationary facility identified 
according to paragraph (c)(4) of this section.

[[Page 194]]

    (3) The plan must require each source to maintain control equipment 
required by this subpart and establish procedures to ensure such control 
equipment is properly operated and maintained.
    (4) For any existing reasonably attributable visibility impairment 
the Federal Land Manager certifies to the State under paragraph (c)(1) 
of this section, at least 6 months prior to plan submission or revision:
    (i) The State must identify and analyze for BART each existing 
stationary facility which may reasonably be anticipated to cause or 
contribute to impairment of visibility in any mandatory Class I Federal 
area where the impairment in the mandatory Class I Federal area is 
reasonably attributable to that existing stationary facility. The State 
need not consider any integral vista the Federal Land Manager did not 
identify pursuant to Sec. 51.304(b) at least 6 months before plan 
submission.
    (ii) If the State determines that technologicial or economic 
limitations on the applicability of measurement methodology to a 
particular existing stationary facility would make the imposition of an 
emission standard infeasible it may instead prescribe a design, 
equipment, work practice, or other operational standard, or combination 
thereof, to require the application of BART. Such standard, to the 
degree possible, is to set forth the emission reduction to be achieved 
by implementation of such design, equipment, work practice or operation, 
and must provide for compliance by means which achieve equivalent 
results.
    (iii) BART must be determined for fossil-fuel fired generating 
plants having a total generating capacity in excess of 750 megawatts 
pursuant to ``Guidelines for Determining Best Available Retrofit 
Technology for Coal-fired Power Plants and Other Existing Stationary 
Facilities'' (1980), which is incorporated by reference, exclusive of 
appendix E, which was published in the Federal Register on February 6, 
1980 (45 FR 8210). It is EPA publication No. 450/3-80-009b and is for 
sale from the U.S. Department of Commerce, National Technical 
Information Service, 5285 Port Royal Road, Springfield, Virginia 22161. 
It is also available for inspection at the Office of the Federal 
Register Information Center, 800 North Capitol NW., suite 700, 
Washington, DC.
    (iv) The plan must require that each existing stationary facility 
required to install and operate BART do so as expeditiously as 
practicable but in no case later than five years after plan approval.
    (v) The plan must provide for a BART analysis of any existing 
stationary facility that might cause or contribute to impairment of 
visibility in any mandatory Class I Federal area identified under this 
paragraph (c)(4) at such times, as determined by the Administrator, as 
new technology for control of the pollutant becomes reasonably available 
if:
    (A) The pollutant is emitted by that existing stationary facility,
    (B) Controls representing BART for the pollutant have not previously 
been required under this subpart, and
    (C) The impairment of visibility in any mandatory Class I Federal 
area is reasonably attributable to the emissions of that pollutant.

[45 FR 80089, Dec. 2, 1980, as amended at 57 FR 40042, Sept. 1, 1992; 64 
FR 35764, 35774, July 1, 1999]



Sec. 51.303  Exemptions from control.

    (a)(1) Any existing stationary facility subject to the requirement 
under Sec. 51.302 to install, operate, and maintain BART may apply to 
the Administrator for an exemption from that requirement.
    (2) An application under this section must include all available 
documentation relevant to the impact of the source's emissions on 
visibility in any mandatory Class I Federal area and a demonstration by 
the existing stationary facility that it does not or will not, by itself 
or in combination with other sources, emit any air pollutant which may 
be reasonably anticipated to cause or contribute to a significant 
impairment of visibility in any mandatory Class I Federal area.
    (b) Any fossil-fuel fired power plant with a total generating 
capacity of 750 megawatts or more may receive an exemption from BART 
only if the owner

[[Page 195]]

or operator of such power plant demonstrates to the satisfaction of the 
Administrator that such power plant is located at such a distance from 
all mandatory Class I Federal areas that such power plant does not or 
will not, by itself or in combination with other sources, emit any air 
pollutant which may reasonably be anticipated to cause or contribute to 
significant impairment of visibility in any such mandatory Class I 
Federal area.
    (c) Application under this Sec. 51.303 must be accompanied by a 
written concurrence from the State with regulatory authority over the 
source.
    (d) The existing stationary facility must give prior written notice 
to all affected Federal Land Managers of any application for exemption 
under this Sec. 51.303.
    (e) The Federal Land Manager may provide an initial recommendation 
or comment on the disposition of such application. Such recommendation, 
where provided, must be part of the exemption application. This 
recommendation is not to be construed as the concurrence required under 
paragraph (h) of this section.
    (f) The Administrator, within 90 days of receipt of an application 
for exemption from control, will provide notice of receipt of an 
exemption application and notice of opportunity for public hearing on 
the application.
    (g) After notice and opportunity for public hearing, the 
Administrator may grant or deny the exemption. For purposes of judicial 
review, final EPA action on an application for an exemption under this 
Sec. 51.303 will not occur until EPA approves or disapproves the State 
Implementation Plan revision.
    (h) An exemption granted by the Administrator under this Sec. 51.303 
will be effective only upon concurrence by all affected Federal Land 
Managers with the Administrator's determination.

[45 FR 80089, Dec. 2, 1980, as amended by 64 FR 35774, July 1, 1999]



Sec. 51.304  Identification of integral vistas.

    (a) On or before December 31, 1985 the Federal Land Manager may 
identify any integral vista. The integral vista must be identified 
according to criteria the Federal Land Manager develops. These criteria 
must include, but are not limited to, whether the integral vista is 
important to the visitor's visual experience of the mandatory Class I 
Federal area. Adoption of criteria must be preceded by reasonable notice 
and opportunity for public comment on the proposed criteria.
    (b) The Federal Land Manager must notify the State of any integral 
vistas identified under paragraph (a) of this section, and the reasons 
therefor.
    (c) The State must list in its implementation plan any integral 
vista the Federal Land Manager identifies at least six months prior to 
plan submission, and must list in its implementation plan at its 
earliest opportunity, and in no case later than at the time of the 
periodic review of the SIP required by Sec. 51.306(c), any integral 
vista the Federal Land Manager identifies after that time.
    (d) The State need not in its implementation plan list any integral 
vista the indentification of which was not made in accordance with the 
criteria in paragraph (a) of this section. In making this finding, the 
State must carefully consider the expertise of the Federal Land Manager 
in making the judgments called for by the criteria for identification. 
Where the State and the Federal Land Manager disagree on the 
identification of any integral vista, the State must give the Federal 
Land Manager an opportunity to consult with the Governor of the State.

[45 FR 80089, Dec. 2, 1980, as amended by 64 FR 35774, July 1, 1999]



Sec. 51.305  Monitoring for reasonably attributable visibility impairment.

    (a) For the purposes of addressing reasonably attributable 
visibility impairment, each State containing a mandatory Class I Federal 
area must include in the plan a strategy for evaluating reasonably 
attributable visibility impairment in any mandatory Class I Federal area 
by visual observation or other appropriate monitoring techniques. Such 
strategy must take into account current and anticipated visibility 
monitoring research, the availability of appropriate monitoring 
techniques, and such guidance as is provided by the Agency.

[[Page 196]]

    (b) The plan must provide for the consideration of available 
visibility data and must provide a mechanism for its use in decisions 
required by this subpart.

[45 FR 80089, Dec. 2, 1980, as amended at 64 FR 35764, July 1, 1999]



Sec. 51.306  Long-term strategy requirements for reasonably attributable visibility impairment.

    (a)(1) For the purposes of addressing reasonably attributable 
visibility impairment, each plan must include a long-term (10-15 years) 
strategy for making reasonable progress toward the national goal 
specified in Sec. 51.300(a). This strategy must cover any existing 
impairment the Federal Land Manager certifies to the State at least 6 
months prior to plan submission, and any integral vista of which the 
Federal Land Manager notifies the State at least 6 months prior to plan 
submission.
    (2) A long-term strategy must be developed for each mandatory Class 
I Federal area located within the State and each mandatory Class I 
Federal area located outside the State which may be affected by sources 
within the State. This does not preclude the development of a single 
comprehensive plan for all such areas.
    (3) The plan must set forth with reasonable specificity why the 
long-term strategy is adequate for making reasonable progress toward the 
national visibility goal, including remedying existing and preventing 
future impairment.
    (b) The State must coordinate its long-term strategy for an area 
with existing plans and goals, including those provided by the affected 
Federal Land Managers, that may affect impairment of visibility in any 
mandatory Class I Federal area.
    (c) The plan must provide for periodic review and revision, as 
appropriate, of the long-term strategy for addressing reasonably 
attributable visibility impairment. The plan must provide for such 
periodic review and revision not less frequently than every 3 years 
until the date of submission of the State's first plan addressing 
regional haze visibility impairment in accordance with Sec. 51.308(b) 
and (c). On or before this date, the State must revise its plan to 
provide for review and revision of a coordinated long-term strategy for 
addressing reasonably attributable and regional haze visibility 
impairment, and the State must submit the first such coordinated long-
term strategy. Future coordinated long-term strategies must be submitted 
consistent with the schedule for periodic progress reports set forth in 
Sec. 51.308(g). Until the State revises its plan to meet this 
requirement, the State must continue to comply with existing 
requirements for plan review and revision, and with all emission 
management requirements in the plan to address reasonably attributable 
impairment. This requirement does not affect any preexisting deadlines 
for State submittal of a long-term strategy review (or element thereof) 
between August 30, 1999, and the date required for submission of the 
State's first regional haze plan. In addition, the plan must provide for 
review of the long-term strategy as it applies to reasonably 
attributable impairment, and revision as appropriate, within 3 years of 
State receipt of any certification of reasonably attributable impairment 
from a Federal Land Manager. The review process must include 
consultation with the appropriate Federal Land Managers, and the State 
must provide a report to the public and the Administrator on progress 
toward the national goal. This report must include an assessment of:
    (1) The progress achieved in remedying existing impairment of 
visibility in any mandatory Class I Federal area;
    (2) The ability of the long-term strategy to prevent future 
impairment of visibility in any mandatory Class I Federal area;
    (3) Any change in visibility since the last such report, or, in the 
case of the first report, since plan approval;
    (4) Additional measures, including the need for SIP revisions, that 
may be necessary to assure reasonable progress toward the national 
visibility goal;
    (5) The progress achieved in implementing BART and meeting other 
schedules set forth in the long-term strategy;
    (6) The impact of any exemption granted under Sec. 51.303;

[[Page 197]]

    (7) The need for BART to remedy existing visibility impairment of 
any integral vista listed in the plan since the last such report, or, in 
the case of the first report, since plan approval.
    (d) The long-term strategy must provide for review of the impacts 
from any new major stationary source or major modifications on 
visibility in any mandatory Class I Federal area. This review of major 
stationary sources or major modifications must be in accordance with 
Sec. 51.307, Sec. 51.166, Sec. 51.160, and any other binding guidance 
provided by the Agency insofar as these provisions pertain to protection 
of visibility in any mandatory Class I Federal areas.
    (e) The State must consider, at a minimum, the following factors 
during the development of its long-term strategy:
    (1) Emission reductions due to ongoing air pollution control 
programs,
    (2) Additional emission limitations and schedules for compliance,
    (3) Measures to mitigate the impacts of construction activities,
    (4) Source retirement and replacement schedules,
    (5) Smoke management techniques for agricultural and forestry 
management purposes including such plans as currently exist within the 
State for these purposes, and
    (6) Enforceability of emission limitations and control measures.
    (f) The plan must discuss the reasons why the above and other 
reasonable measures considered in the development of the long-term 
strategy were or were not adopted as part of the long-term strategy.
    (g) The State, in developing the long-term strategy, must take into 
account the effect of new sources, and the costs of compliance, the time 
necessary for compliance, the energy and nonair quality environmental 
impacts of compliance, and the remaining useful life of any affected 
existing source and equipment therein.

[45 FR 80089, Dec. 2, 1980, as amended at 64 FR 35764, 35774, July 1, 
1999]



Sec. 51.307  New source review.

    (a) For purposes of new source review of any new major stationary 
source or major modification that would be constructed in an area that 
is designated attainment or unclassified under section 107(d)(1)(D) or 
(E) of the CAA, the State plan must, in any review under Sec. 51.166 
with respect to visibility protection and analyses, provide for:
    (1) Written notification of all affected Federal Land Managers of 
any proposed new major stationary source or major modification that may 
affect visibility in any Federal Class I area. Such notification must be 
made in writing and include a copy of all information relevant to the 
permit application within 30 days of receipt of and at least 60 days 
prior to public hearing by the State on the application for permit to 
construct. Such notification must include an analysis of the anticipated 
impacts on visibility in any Federal Class I area,
    (2) Where the State requires or receives advance notification (e.g. 
early consultation with the source prior to submission of the 
application or notification of intent to monitor under Sec. 51.166) of a 
permit application of a source that may affect visibility the State must 
notify all affected Federal Land Managers within 30 days of such advance 
notification, and
    (3) Consideration of any analysis performed by the Federal Land 
Manager, provided within 30 days of the notification and analysis 
required by paragraph (a)(1) of this section, that such proposed new 
major stationary source or major modification may have an adverse impact 
on visibility in any Federal Class I area. Where the State finds that 
such an analysis does not demonstrate to the satisfaction of the State 
that an adverse impact will result in the Federal Class I area, the 
State must, in the notice of public hearing, either explain its decision 
or give notice as to where the explanation can be obtained.
    (b) The plan shall also provide for the review of any new major 
stationary source or major modification:
    (1) That may have an impact on any integral vista of a mandatory 
Class I Federal area, if it is identified in accordance with Sec. 51.304 
by the Federal Land Manager at least 12 months before submission of a 
complete permit application, except where the Federal Land Manager has 
provided notice and opportunity for public comment on the

[[Page 198]]

integral vista in which case the review must include impacts on any 
integral vista identified at least 6 months prior to submission of a 
complete permit application, unless the State determines under 
Sec. 51.304(d) that the identification was not in accordance with the 
identification criteria, or
    (2) That proposes to locate in an area classified as nonattainment 
under section 107(d)(1)(A), (B), or (C) of the Clean Air Act that may 
have an impact on visibility in any mandatory Class I Federal area.
    (c) Review of any major stationary source or major modification 
under paragraph (b) of this section, shall be conducted in accordance 
with paragraph (a) of this section, and Sec. 51.166(o), (p)(1) through 
(2), and (q). In conducting such reviews the State must ensure that the 
source's emissions will be consistent with making reasonable progress 
toward the national visibility goal referred to in Sec. 51.300(a). The 
State may take into account the costs of compliance, the time necessary 
for compliance, the energy and nonair quality environmental impacts of 
compliance, and the useful life of the source.
    (d) The State may require monitoring of visibility in any Federal 
Class I area near the proposed new stationary source or major 
modification for such purposes and by such means as the State deems 
necessary and appropriate.

[45 FR 80089, Dec. 2, 1980, as amended at 64 FR 35765, 35774, July 1, 
1999]



Sec. 51.308  Regional haze program requirements.

    (a) What is the purpose of this section? This section establishes 
requirements for implementation plans, plan revisions, and periodic 
progress reviews to address regional haze.
    (b) When are the first implementation plans due under the regional 
haze program? Except as provided in paragraph (c) of this section and 
Sec. 51.309(c), each State identified in Sec. 51.300(b)(3) must submit 
an implementation plan for regional haze meeting the requirements of 
paragraphs (d) and (e) of this section by the following dates:
    (1) For any area designated as attainment or unclassifiable for the 
national ambient air quality standard (NAAQS) for fine particulate 
matter (PM2.5), the State must submit a regional haze 
implementation plan to EPA within 12 months after the date of 
designation.
    (2) For any area designated as nonattainment for the 
PM2.5 NAAQS, the State must submit a regional haze 
implementation plan to EPA at the same time that the State's plan for 
implementation of the PM2.5 NAAQS must be submitted under 
section 172 of the CAA, that is, within 3 years after the area is 
designated as nonattainment, but not later than December 31, 2008.
    (c) Options for regional planning. If at the time the SIP for 
regional haze would otherwise be due, a State is working with other 
States to develop a coordinated approach to regional haze by 
participating in a regional planning process, the State may choose to 
defer addressing the core requirements for regional haze in paragraph 
(d) of this section and the requirements for BART in paragraph (e) of 
this section. If a State opts to do this, it must meet the following 
requirements:
    (1) The State must submit an implementation plan by the earliest 
date by which an implementation plan would be due for any area of the 
State under paragraph (b) of this section. This implementation plan must 
contain the following:
    (i) A demonstration of ongoing participation in a regional planning 
process to address regional haze, and an agreement by the State to 
continue participating with one or more other States in such a process 
for the development of this and future implementation plan revisions;
    (ii) A showing, based on available inventory, monitoring, or 
modeling information, that emissions from within the State contribute to 
visibility impairment in a mandatory Class I Federal Area outside the 
State, or that emissions from another State contribute to visibility 
impairment in any mandatory Class I Federal area within the State.
    (iii) A description of the regional planning process, including a 
list of the States which have agreed to work together to address 
regional haze in a region (i.e., the regional planning group), the 
goals, objectives, management, and

[[Page 199]]

decisionmaking structure of the regional planning group, deadlines for 
completing significant technical analyses and developing emission 
management strategies, and a schedule for State review and adoption of 
regulations implementing the recommendations of the regional group;
    (iv) A commitment by the State to submit an implementation plan 
revision addressing the requirements in paragraphs (d) and (e) of this 
section by the date specified in paragraph (c)(2) of this section. In 
addition, the State must commit to develop its plan revision in 
coordination with the other States participating in the regional 
planning process, and to fully address the recommendations of the 
regional planning group.
    (v) A list of all BART-eligible sources within the State.
    (2) The State must submit an implementation plan revision addressing 
the requirements in paragraphs (d) and (e) of this section by the latest 
date an area within the planning region would be required to submit an 
implementation plan under paragraph (b) of this section, but in any 
event, no later than December 31, 2008.
    (d) What are the core requirements for the implementation plan for 
regional haze? The State must address regional haze in each mandatory 
Class I Federal area located within the State and in each mandatory 
Class I Federal area located outside the State which may be affected by 
emissions from within the State. To meet the core requirements for 
regional haze for these areas, the State must submit an implementation 
plan containing the following plan elements and supporting documentation 
for all required analyses:
    (1) Reasonable progress goals. For each mandatory Class I Federal 
area located within the State, the State must establish goals (expressed 
in deciviews) that provide for reasonable progress towards achieving 
natural visibility conditions. The reasonable progress goals must 
provide for an improvement in visibility for the most impaired days over 
the period of the implementation plan and ensure no degradation in 
visibility for the least impaired days over the same period.
    (i) In establishing a reasonable progress goal for any mandatory 
Class I Federal area within the State, the State must:
    (A) Consider the costs of compliance, the time necessary for 
compliance, the energy and non-air quality environmental impacts of 
compliance, and the remaining useful life of any potentially affected 
sources, and include a demonstration showing how these factors were 
taken into consideration in selecting the goal.
    (B) Analyze and determine the rate of progress needed to attain 
natural visibility conditions by the year 2064. To calculate this rate 
of progress, the State must compare baseline visibility conditions to 
natural visibility conditions in the mandatory Federal Class I area and 
determine the uniform rate of visibility improvement (measured in 
deciviews) that would need to be maintained during each implementation 
period in order to attain natural visibility conditions by 2064. In 
establishing the reasonable progress goal, the State must consider the 
uniform rate of improvement in visibility and the emission reduction 
measures needed to achieve it for the period covered by the 
implementation plan.
    (ii) For the period of the implementation plan, if the State 
establishes a reasonable progress goal that provides for a slower rate 
of improvement in visibility than the rate that would be needed to 
attain natural conditions by 2064, the State must demonstrate, based on 
the factors in paragraph (d)(1)(i)(A) of this section, that the rate of 
progress for the implementation plan to attain natural conditions by 
2064 is not reasonable; and that the progress goal adopted by the State 
is reasonable. The State must provide to the public for review as part 
of its implementation plan an assessment of the number of years it would 
take to attain natural conditions if visibility improvement continues at 
the rate of progress selected by the State as reasonable.
    (iii) In determining whether the State's goal for visibility 
improvement provides for reasonable progress towards natural visibility 
conditions, the

[[Page 200]]

Administrator will evaluate the demonstrations developed by the State 
pursuant to paragraphs (d)(1)(i) and (d)(1)(ii) of this section.
    (iv) In developing each reasonable progress goal, the State must 
consult with those States which may reasonably be anticipated to cause 
or contribute to visibility impairment in the mandatory Class I Federal 
area. In any situation in which the State cannot agree with another such 
State or group of States that a goal provides for reasonable progress, 
the State must describe in its submittal the actions taken to resolve 
the disagreement. In reviewing the State's implementation plan 
submittal, the Administrator will take this information into account in 
determining whether the State's goal for visibility improvement provides 
for reasonable progress towards natural visibility conditions.
    (v) The reasonable progress goals established by the State are not 
directly enforceable but will be considered by the Administrator in 
evaluating the adequacy of the measures in the implementation plan to 
achieve the progress goal adopted by the State.
    (vi) The State may not adopt a reasonable progress goal that 
represents less visibility improvement than is expected to result from 
implementation of other requirements of the CAA during the applicable 
planning period.
    (2) Calculations of baseline and natural visibility conditions. For 
each mandatory Class I Federal area located within the State, the State 
must determine the following visibility conditions (expressed in 
deciviews):
    (i) Baseline visibility conditions for the most impaired and least 
impaired days. The period for establishing baseline visibility 
conditions is 2000 to 2004. Baseline visibility conditions must be 
calculated, using available monitoring data, by establishing the average 
degree of visibility impairment for the most and least impaired days for 
each calendar year from 2000 to 2004. The baseline visibility conditions 
are the average of these annual values. For mandatory Class I Federal 
areas without onsite monitoring data for 2000-2004, the State must 
establish baseline values using the most representative available 
monitoring data for 2000-2004, in consultation with the Administrator or 
his or her designee;
    (ii) For an implementation plan that is submitted by 2003, the 
period for establishing baseline visibility conditions for the period of 
the first long-term strategy is the most recent 5-year period for which 
visibility monitoring data are available for the mandatory Class I 
Federal areas addressed by the plan. For mandatory Class I Federal areas 
without onsite monitoring data, the State must establish baseline values 
using the most representative available monitoring data, in consultation 
with the Administrator or his or her designee;
    (iii) Natural visibility conditions for the most impaired and least 
impaired days. Natural visibility conditions must be calculated by 
estimating the degree of visibility impairment existing under natural 
conditions for the most impaired and least impaired days, based on 
available monitoring information and appropriate data analysis 
techniques; and
    (iv)(A) For the first implementation plan addressing the 
requirements of paragraphs (d) and (e) of this section, the number of 
deciviews by which baseline conditions exceed natural visibility 
conditions for the most impaired and least impaired days; or
    (B) For all future implementation plan revisions, the number of 
deciviews by which current conditions, as calculated under paragraph 
(f)(1) of this section, exceed natural visibility conditions for the 
most impaired and least impaired days.
    (3) Long-term strategy for regional haze. Each State listed in 
Sec. 51.300(b)(3) must submit a long-term strategy that addresses 
regional haze visibility impairment for each mandatory Class I Federal 
area within the State and for each mandatory Class I Federal area 
located outside the State which may be affected by emissions from the 
State. The long-term strategy must include enforceable emissions 
limitations, compliance schedules, and other measures as necessary to 
achieve the reasonable progress goals established by States having 
mandatory Class I Federal areas. In establishing its long-term strategy 
for regional haze, the

[[Page 201]]

State must meet the following requirements:
    (i) Where the State has emissions that are reasonably anticipated to 
contribute to visibility impairment in any mandatory Class I Federal 
area located in another State or States, the State must consult with the 
other State(s) in order to develop coordinated emission management 
strategies. The State must consult with any other State having emissions 
that are reasonably anticipated to contribute to visibility impairment 
in any mandatory Class I Federal area within the State.
    (ii) Where other States cause or contribute to impairment in a 
mandatory Class I Federal area, the State must demonstrate that it has 
included in its implementation plan all measures necessary to obtain its 
share of the emission reductions needed to meet the progress goal for 
the area. If the State has participated in a regional planning process, 
the State must ensure it has included all measures needed to achieve its 
apportionment of emission reduction obligations agreed upon through that 
process.
    (iii) The State must document the technical basis, including 
modeling, monitoring and emissions information, on which the State is 
relying to determine its apportionment of emission reduction obligations 
necessary for achieving reasonable progress in each mandatory Class I 
Federal area it affects. The State may meet this requirement by relying 
on technical analyses developed by the regional planning organization 
and approved by all State participants. The State must identify the 
baseline emissions inventory on which its strategies are based. The 
baseline emissions inventory year is presumed to be the most recent year 
of the consolidate periodic emissions inventory.
    (iv) The State must identify all anthropogenic sources of visibility 
impairment considered by the State in developing its long-term strategy. 
The State should consider major and minor stationary sources, mobile 
sources, and area sources.
    (v) The State must consider, at a minimum, the following factors in 
developing its long-term strategy:
    (A) Emission reductions due to ongoing air pollution control 
programs, including measures to address reasonably attributable 
visibility impairment;
    (B) Measures to mitigate the impacts of construction activities;
    (C) Emissions limitations and schedules for compliance to achieve 
the reasonable progress goal;
    (D) Source retirement and replacement schedules;
    (E) Smoke management techniques for agricultural and forestry 
management purposes including plans as currently exist within the State 
for these purposes;
    (F) Enforceability of emissions limitations and control measures; 
and
    (G) The anticipated net effect on visibility due to projected 
changes in point, area, and mobile source emissions over the period 
addressed by the long-term strategy.
    (4) Monitoring strategy and other implementation plan requirements. 
The State must submit with the implementation plan a monitoring strategy 
for measuring, characterizing, and reporting of regional haze visibility 
impairment that is representative of all mandatory Class I Federal areas 
within the State. This monitoring strategy must be coordinated with the 
monitoring strategy required in Sec. 51.305 for reasonably attributable 
visibility impairment. Compliance with this requirement may be met 
through participation in the Interagency Monitoring of Protected Visual 
Environments network. The implementation plan must also provide for the 
following:
    (i) The establishment of any additional monitoring sites or 
equipment needed to assess whether reasonable progress goals to address 
regional haze for all mandatory Class I Federal areas within the State 
are being achieved.
    (ii) Procedures by which monitoring data and other information are 
used in determining the contribution of emissions from within the State 
to regional haze visibility impairment at mandatory Class I Federal 
areas both within and outside the State.
    (iii) For a State with no mandatory Class I Federal areas, 
procedures by which monitoring data and other information are used in 
determining the contribution of emissions from within

[[Page 202]]

the State to regional haze visibility impairment at mandatory Class I 
Federal areas in other States.
    (iv) The implementation plan must provide for the reporting of all 
visibility monitoring data to the Administrator at least annually for 
each mandatory Class I Federal area in the State. To the extent 
possible, the State should report visibility monitoring data 
electronically.
    (v) A statewide inventory of emissions of pollutants that are 
reasonably anticipated to cause or contribute to visibility impairment 
in any mandatory Class I Federal area. The inventory must include 
emissions for a baseline year, emissions for the most recent year for 
which data are available, and estimates of future projected emissions. 
The State must also include a commitment to update the inventory 
periodically.
    (vi) Other elements, including reporting, recordkeeping, and other 
measures, necessary to assess and report on visibility.
    (e) Best Available Retrofit Technology (BART) requirements for 
regional haze visibility impairment. The State must submit an 
implementation plan containing emission limitations representing BART 
and schedules for compliance with BART for each BART-eligible source 
that may reasonably be anticipated to cause or contribute to any 
impairment of visibility in any mandatory Class I Federal area, unless 
the State demonstrates that an emissions trading program or other 
alternative will achieve greater reasonable progress toward natural 
visibility conditions.
    (1) To address the requirements for BART, the State must submit an 
implementation plan containing the following plan elements and include 
documentation for all required analyses:
    (i) A list of all BART-eligible sources within the State.
    (ii) A determination of BART for each BART-eligible source in the 
State that emits any air pollutant which may reasonably be anticipated 
to cause or contribute to any impairment of visibility in any mandatory 
Class I Federal area. All such sources are subject to BART. This 
determination must be based on the following analyses:
    (A) An analysis of the best system of continuous emission control 
technology available and associated emission reductions achievable for 
each BART-eligible source within the State subject to BART. In this 
analysis, the State must take into consideration the technology 
available, the costs of compliance, the energy and nonair quality 
environmental impacts of compliance, any pollution control equipment in 
use at the source, and the remaining useful life of the source; and
    (B) An analysis of the degree of visibility improvement that would 
be achieved in each mandatory Class I Federal area as a result of the 
emission reductions achievable from all sources subject to BART located 
within the region that contributes to visibility impairment in the Class 
I area, based on the analysis conducted under paragraph (e)(1)(ii)(A) of 
this section.
    (iii) If the State determines in establishing BART that 
technological or economic limitations on the applicability of 
measurement methodology to a particular source would make the imposition 
of an emission standard infeasible, it may instead prescribe a design, 
equipment, work practice, or other operational standard, or combination 
thereof, to require the application of BART. Such standard, to the 
degree possible, is to set forth the emission reduction to be achieved 
by implementation of such design, equipment, work practice or operation, 
and must provide for compliance by means which achieve equivalent 
results.
    (iv) A requirement that each source subject to BART be required to 
install and operate BART as expeditiously as practicable, but in no 
event later than 5 years after approval of the implementation plan 
revision.
    (v) A requirement that each source subject to BART maintain the 
control equipment required by this subpart and establish procedures to 
ensure such equipment is properly operated and maintained.
    (2) A State may opt to implement an emissions trading program or 
other alternative measure rather than to require sources subject to BART 
to install, operate, and maintain BART. To do so, the State must 
demonstrate that this emissions trading program or

[[Page 203]]

other alternative measure will achieve greater reasonable progress than 
would be achieved through the installation and operation of BART. To 
make this demonstration, the State must submit an implementation plan 
containing the following plan elements and include documentation for all 
required analyses:
    (i) A demonstration that the emissions trading program or other 
alternative measure will achieve greater reasonable progress than would 
have resulted from the installation and operation of BART at all sources 
subject to BART in the State. This demonstration must be based on the 
following:
    (A) A list of all BART-eligible sources within the State.
    (B) An analysis of the best system of continuous emission control 
technology available and associated emission reductions achievable for 
each source within the State subject to BART. In this analysis, the 
State must take into consideration the technology available, the costs 
of compliance, the energy and nonair quality environmental impacts of 
compliance, any pollution control equipment in use at the source, and 
the remaining useful life of the source. The best system of continuous 
emission control technology and the above factors may be determined on a 
source category basis. The State may elect to consider both source-
specific and category-wide information, as appropriate, in conducting 
its analysis.
    (C) An analysis of the degree of visibility improvement that would 
be achieved in each mandatory Class I Federal area as a result of the 
emission reductions achievable from all such sources subject to BART 
located within the region that contributes to visibility impairment in 
the Class I area, based on the analysis conducted under paragraph 
(e)(2)(i)(B) of this section.
    (ii) A demonstration that the emissions trading program or 
alternative measure will apply, at a minimum, to all BART-eligible 
sources in the State. Those sources having a federally enforceable 
emission limitation determined by the State and approved by EPA as 
meeting BART in accordance with Sec. 51.302(c) or paragraph (e)(1) of 
this section do not need to meet the requirements of the emissions 
trading program or alternative measure, but may choose to participate if 
they meet the requirements of the emissions trading program or 
alternative measure.
    (iii) A requirement that all necessary emission reductions take 
place during the period of the first long-term strategy for regional 
haze. To meet this requirement, the State must provide a detailed 
description of the emissions trading program or other alternative 
measure, including schedules for implementation, the emission reductions 
required by the program, all necessary administrative and technical 
procedures for implementing the program, rules for accounting and 
monitoring emissions, and procedures for enforcement.
    (iv) A demonstration that the emission reductions resulting from the 
emissions trading program or other alternative measure will be surplus 
to those reductions resulting from measures adopted to meet requirements 
of the CAA as of the baseline date of the SIP.
    (v) At the State's option, a provision that the emissions trading 
program or other alternative measure may include a geographic 
enhancement to the program to address the requirement under 
Sec. 51.302(c) related to BART for reasonably attributable impairment 
from the pollutants covered under the emissions trading program or other 
alternative measure.
    (3) After a State has met the requirements for BART or implemented 
emissions trading program or other alternative measure that achieve more 
reasonable progress than the installation and operation of BART, BART-
eligible sources will be subject to the requirements of paragraph (d) of 
this section in the same manner as other sources.
    (4) Any BART-eligible facility subject to the requirement under 
paragraph (e) of this section to install, operate, and maintain BART may 
apply to the Administrator for an exemption from that requirement. An 
application for an exemption will be subject to the requirements of 
Sec. 51.303 (a)(2) through (h).
    (f) Requirements for comprehensive periodic revisions of 
implementation plans for regional haze. Each State identified in 
Sec. 51.300(b)(3) must revise and submit its

[[Page 204]]

regional haze implementation plan revision to EPA by July 31, 2018 and 
every ten years thereafter. In each plan revision, the State must 
evaluate and reassess all of the elements required in paragraph (d) of 
this section, taking into account improvements in monitoring data 
collection and analysis techniques, control technologies, and other 
relevant factors. In evaluating and reassessing these elements, the 
State must address the following:
    (1) Current visibility conditions for the most impaired and least 
impaired days, and actual progress made towards natural conditions 
during the previous implementation period. The period for calculating 
current visibility conditions is the most recent five year period 
preceding the required date of the implementation plan submittal for 
which data are available. Current visibility conditions must be 
calculated based on the annual average level of visibility impairment 
for the most and least impaired days for each of these five years. 
Current visibility conditions are the average of these annual values.
    (2) The effectiveness of the long-term strategy for achieving 
reasonable progress goals over the prior implementation period(s); and
    (3) Affirmation of, or revision to, the reasonable progress goal in 
accordance with the procedures set forth in paragraph (d)(1) of this 
section. If the State established a reasonable progress goal for the 
prior period which provided a slower rate of progress than that needed 
to attain natural conditions by the year 2064, the State must evaluate 
and determine the reasonableness, based on the factors in paragraph 
(d)(1)(i)(A) of this section, of additional measures that could be 
adopted to achieve the degree of visibility improvement projected by the 
analysis contained in the first implementation plan described in 
paragraph (d)(1)(i)(B) of this section.
    (g) Requirements for periodic reports describing progress towards 
the reasonable progress goals. Each State identified in 
Sec. 51.300(b)(3) must submit a report to the Administrator every 5 
years evaluating progress towards the reasonable progress goal for each 
mandatory Class I Federal area located within the State and in each 
mandatory Class I Federal area located outside the State which may be 
affected by emissions from within the State. The first progress report 
is due 5 years from submittal of the initial implementation plan 
addressing paragraphs (d) and (e) of this section. The progress reports 
must be in the form of implementation plan revisions that comply with 
the procedural requirements of Sec. 51.102 and Sec. 51.103. Periodic 
progress reports must contain at a minimum the following elements:
    (1) A description of the status of implementation of all measures 
included in the implementation plan for achieving reasonable progress 
goals for mandatory Class I Federal areas both within and outside the 
State.
    (2) A summary of the emissions reductions achieved throughout the 
State through implementation of the measures described in paragraph 
(g)(1) of this section.
    (3) For each mandatory Class I Federal area within the State, the 
State must assess the following visibility conditions and changes, with 
values for most impaired and least impaired days expressed in terms of 
5-year averages of these annual values.
    (i) The current visibility conditions for the most impaired and 
least impaired days;
    (ii) The difference between current visibility conditions for the 
most impaired and least impaired days and baseline visibility 
conditions;
    (iii) The change in visibility impairment for the most impaired and 
least impaired days over the past 5 years;
    (4) An analysis tracking the change over the past 5 years in 
emissions of pollutants contributing to visibility impairment from all 
sources and activities within the State. Emissions changes should be 
identified by type of source or activity. The analysis must be based on 
the most recent updated emissions inventory, with estimates projected 
forward as necessary and appropriate, to account for emissions changes 
during the applicable 5-year period.
    (5) An assessment of any significant changes in anthropogenic 
emissions within or outside the State that have occurred over the past 5 
years that

[[Page 205]]

have limited or impeded progress in reducing pollutant emissions and 
improving visibility.
    (6) An assessment of whether the current implementation plan 
elements and strategies are sufficient to enable the State, or other 
States with mandatory Federal Class I areas affected by emissions from 
the State, to meet all established reasonable progress goals.
    (7) A review of the State's visibility monitoring strategy and any 
modifications to the strategy as necessary.
    (h) Determination of the adequacy of existing implementation plan. 
At the same time the State is required to submit any 5-year progress 
report to EPA in accordance with paragraph (g) of this section, the 
State must also take one of the following actions based upon the 
information presented in the progress report:
    (1) If the State determines that the existing implementation plan 
requires no further substantive revision at this time in order to 
achieve established goals for visibility improvement and emissions 
reductions, the State must provide to the Administrator a negative 
declaration that further revision of the existing implementation plan is 
not needed at this time.
    (2) If the State determines that the implementation plan is or may 
be inadequate to ensure reasonable progress due to emissions from 
sources in another State(s) which participated in a regional planning 
process, the State must provide notification to the Administrator and to 
the other State(s) which participated in the regional planning process 
with the States. The State must also collaborate with the other State(s) 
through the regional planning process for the purpose of developing 
additional strategies to address the plan's deficiencies.
    (3) Where the State determines that the implementation plan is or 
may be inadequate to ensure reasonable progress due to emissions from 
sources in another country, the State shall provide notification, along 
with available information, to the Administrator.
    (4) Where the State determines that the implementation plan is or 
may be inadequate to ensure reasonable progress due to emissions from 
sources within the State, the State shall revise its implementation plan 
to address the plan's deficiencies within one year.
    (i) What are the requirements for State and Federal Land Manager 
coordination?
    (1) By November 29, 1999, the State must identify in writing to the 
Federal Land Managers the title of the official to which the Federal 
Land Manager of any mandatory Class I Federal area can submit any 
recommendations on the implementation of this subpart including, but not 
limited to:
    (i) Identification of impairment of visibility in any mandatory 
Class I Federal area(s); and
    (ii) Identification of elements for inclusion in the visibility 
monitoring strategy required by Sec. 51.305 and this section.
    (2) The State must provide the Federal Land Manager with an 
opportunity for consultation, in person and at least 60 days prior to 
holding any public hearing on an implementation plan (or plan revision) 
for regional haze required by this subpart. This consultation must 
include the opportunity for the affected Federal Land Managers to 
discuss their:
    (i) Assessment of impairment of visibility in any mandatory Class I 
Federal area; and
    (ii) Recommendations on the development of the reasonable progress 
goal and on the development and implementation of strategies to address 
visibility impairment.
    (3) In developing any implementation plan (or plan revision), the 
State must include a description of how it addressed any comments 
provided by the Federal Land Managers.
    (4) The plan (or plan revision) must provide procedures for 
continuing consultation between the State and Federal Land Manager on 
the implementation of the visibility protection program required by this 
subpart, including development and review of implementation plan 
revisions and 5-year progress reports, and on the implementation of 
other programs having the potential to contribute to impairment of 
visibility in mandatory Class I Federal areas.

[64 FR 35765, July 1, 1999]

[[Page 206]]



Sec. 51.309  Requirements related to the Grand Canyon Visibility Transport Commission.

    (a) What is the purpose of this section? This section establishes 
the requirements for the first regional haze implementation plan to 
address regional haze visibility impairment in the 16 Class I areas 
covered by the Grand Canyon Visibility Transport Commission Report. For 
the years 2003 to 2018, certain States (defined in paragraph (b) of this 
section as Transport Region States) may choose to implement the 
Commission's recommendations within the framework of the national 
regional haze program and applicable requirements of the Act by 
complying with the provisions of this section, as supplemented by an 
approvable Annex to the Commission Report as required by paragraph (f) 
of this section. If a transport region State submits an implementation 
plan which is approved by EPA as meeting the requirements of this 
section, it will be deemed to comply with the requirements for 
reasonable progress for the period from approval of the plan to 2018.
    (b) Definitions. For the purposes of this section:
    (1) 16 Class I areas means the following mandatory Class I Federal 
areas on the Colorado Plateau: Grand Canyon National Park, Sycamore 
Canyon Wilderness, Petrified Forest National Park, Mount Baldy 
Wilderness, San Pedro Parks Wilderness, Mesa Verde National Park, 
Weminuche Wilderness, Black Canyon of the Gunnison Wilderness, West Elk 
Wilderness, Maroon Bells Wilderness, Flat Tops Wilderness, Arches 
National Park, Canyonlands National Park, Capital Reef National Park, 
Bryce Canyon National Park, and Zion National Park.
    (2) Transport Region State means one of the States that is included 
within the Transport Region addressed by the Grand Canyon Visibility 
Transport Commission (Arizona, California, Colorado, Idaho, Nevada, New 
Mexico, Oregon, Utah, and Wyoming).
    (3) Commission Report means the report of the Grand Canyon 
Visibility Transport Commission entitled ``Recommendations for Improving 
Western Vistas,'' dated June 10, 1996.
    (4) Fire means wildfire, wildland fire (including prescribed natural 
fire), prescribed fire, and agricultural burning conducted and occurring 
on Federal, State, and private wildlands and farmlands.
    (5) Milestone means an average percentage reduction in emissions, 
expressed in tons per year, for a given year or for a period of up to 5 
years ending in that year, compared to a 1990 actual emissions baseline.
    (6) Mobile Source Emission Budget means the lowest level of VOC, 
NOX, SO2 elemental and organic carbon, and fine 
particles which are projected to occur in any area within the transport 
region from which mobile source emissions are determined to contribute 
significantly to visibility impairment in any of the 16 Class I areas.
    (7) Geographic enhancement means a method, procedure, or process to 
allow a broad regional strategy, such as a milestone or backstop market 
trading program designed to achieve greater reasonable progress than 
BART for regional haze, to accommodate BART for reasonably attributable 
impairment.
    (c) Implementation Plan Schedule. Each Transport Region State may 
meet the requirements of Sec. 51.308(b) through (e) by electing to 
submit an implementation plan that complies with the requirements of 
this section. Each Transport Region State must submit an implementation 
plan addressing regional haze visibility impairment in the 16 Class I 
areas no later than December 31, 2003. A Transport Region State that 
elects not to submit an implementation plan that complies with the 
requirements of this section (or whose plan does not comply with all of 
the requirements of this section) is subject to the requirements of 
Sec. 51.308 in the same manner and to the same extent as any State not 
included within the Transport Region.
    (d) Requirements of the first implementation plan for States 
electing to adopt all of the recommendations of the Commission Report. 
Except as provided for in paragraph (e) of this section, each Transport 
Region State must submit an implementation plan that meets the following 
requirements:
    (1) Time period covered. The implementation plan must be effective 
for

[[Page 207]]

the entire time period between December 31, 2003 and December 31, 2018.
    (2) Projection of visibility improvement. For each of the 16 
mandatory Class I areas located within the Transport Region State, the 
plan must include a projection of the improvement in visibility 
conditions (expressed in deciviews, and in any additional ambient 
visibility metrics deemed appropriate by the State) expected through the 
year 2018 for the most impaired and least impaired days, based on the 
implementation of all measures as required in the Commission report and 
the provisions in this section. The projection must be made in 
consultation with other Transport Region States with sources which may 
be reasonably anticipated to contribute to visibility impairment in the 
relevant Class I area. The projection may be based on a satisfactory 
regional analysis.
    (3) Treatment of clean-air corridors. The plan must describe and 
provide for implementation of comprehensive emission tracking strategies 
for clean-air corridors to ensure that the visibility does not degrade 
on the least-impaired days at any of the 16 Class I areas. The strategy 
must include:
    (i) An identification of clean-air corridors. The EPA will evaluate 
the State's identification of such corridors based upon the reports of 
the Commission's Meteorology Subcommittee and any future updates by a 
successor organization;
    (ii) Within areas that are clean-air corridors, an identification of 
patterns of growth or specific sites of growth that could cause, or are 
causing, significant emissions increases that could have, or are having, 
visibility impairment at one or more of the 16 Class I areas.
    (iii) In areas outside of clean-air corridors, an identification of 
significant emissions growth that could begin, or is beginning, to 
impair the quality of air in the corridor and thereby lead to visibility 
degradation for the least-impaired days in one or more of the 16 Class I 
areas.
    (iv) If impairment of air quality in clean air corridors is 
identified pursuant to paragraphs (d)(3)(ii) and (iii) of this section, 
an analysis of the effects of increased emissions, including provisions 
for the identification of the need for additional emission reductions 
measures, and implementation of the additional measures where necessary.
    (v) A determination of whether other clean air corridors exist for 
any of the 16 Class I areas. For any such clean air corridors, an 
identification of the necessary measures to protect against future 
degradation of air quality in any of the 16 Class I areas.
    (4) Implementation of stationary source reductions. The first 
implementation plan submission must include:
    (i) Monitoring and reporting of sulfur dioxide emissions. The plan 
submission must include provisions requiring the monitoring and 
reporting of actual stationary source sulfur dioxide emissions within 
the State. The monitoring and reporting data must be sufficient to 
determine whether a 13 percent reduction in actual stationary source 
sulfur dioxide emissions has occurred between the years 1990 and 2000, 
and whether milestones required by paragraph (f)(1)(i) of this section 
have been achieved for the transport region. The plan submission must 
provide for reporting of these data by the State to the Administrator. 
Where procedures developed under paragraph (f)(1)(ii) of this section 
and agreed upon by the State include reporting to a regional planning 
organization, the plan submission must provide for reporting to the 
regional planning body in addition to the Administrator.
    (ii) Criteria and procedures for a market trading program. The plan 
must include the criteria and procedures for activating a market trading 
program or other program consistent with paragraph (f)(1)(i) of this 
section if an applicable regional milestone is exceeded, procedures for 
operation of the program, and implementation plan assessments and 
provisions for implementation plan assessments of the program in the 
years 2008, 2013, and 2018.
    (iii) Provisions for activating a market trading program. Provisions 
to activate the market trading program or other program within 12 months 
after the emissions for the region are determined to exceed the 
applicable emission reduction milestone, and to assure

[[Page 208]]

that all affected sources are in compliance with allocation and other 
requirements within 5 years after the emissions for the region are 
determined to exceed the applicable emission reduction milestone.
    (iv) Provisions for market trading program compliance reporting. If 
the market trading program has been activated, the plan submission must 
include provisions requiring the State to provide annual reports 
assuring that all sources are in compliance with applicable requirements 
of the market trading program.
    (v) Provisions for stationary source NOX and PM. The plan 
submission must include a report which assesses emissions control 
strategies for stationary source NOX and PM, and the degree 
of visibility improvement that would result from such strategies. In the 
report, the State must evaluate and discuss the need to establish 
emission milestones for NOX and PM to avoid any net increase 
in these pollutants from stationary sources within the transport region, 
and to support potential future development and implementation of a 
multipollutant and possibly multisource market-based program. The plan 
submission must provide for an implementation plan revision, containing 
any necessary long-term strategies and BART requirements for stationary 
source PM and NOX (including enforceable limitations, 
compliance schedules, and other measures) by no later than December 31, 
2008.
    (5) Mobile sources. The plan submission must provide for:
    (i) Statewide inventories of current annual emissions and projected 
future annual emissions of VOc, NOX, 
SO2, elemental carbon, organic carbon, and fine particles 
from mobile sources for the years 2003 to 2018. The future year 
inventories must include projections for the year 2005, or an 
alternative year that is determined by the State to represent the year 
during which mobile source emissions will be at their lowest levels 
within the State.
    (ii) A determination whether mobile source emissions in any areas of 
the State contribute significantly to visibility impairment in any of 
the 16 Class I Areas, based on the statewide inventory of current and 
projected mobile source emissions.
    (iii) For States with areas in which mobile source emissions are 
found to contribute significantly to visibility impairment in any of the 
16 Class I areas:
    (A) The establishment and documentation of a mobile source emissions 
budget for any such area, including provisions requiring the State to 
restrict the annual VOC, NOX, SO2, elemental and 
organic carbon, and/or fine particle mobile source emissions to their 
projected lowest levels, to implement measures to achieve the budget or 
cap, and to demonstrate compliance with the budget.
    (B) An emission tracking system providing for reporting of annual 
mobile source emissions from the State in the periodic implementation 
plan revisions required by paragraph (d)(10) of this section. The 
emission tracking system must be sufficient to determine the States' 
contribution toward the Commission's objective of reducing emissions 
from mobile sources by 2005 or an alternate year that is determined by 
the State to represent the year during which mobile source emissions 
will be at their lowest levels within the State, and to ensure that 
mobile source emissions do not increase thereafter.
    (iv) Interim reports to EPA and the public in years 2003, 2008, 
2013, and 2018 on the implementation status of the regional and local 
strategies recommended by the Commission Report to address mobile source 
emissions.
    (6) Programs related to fire. The plan must provide for:
    (i) Documentation that all Federal, State, and private prescribed 
fire programs within the State evaluate and address the degree 
visibility impairment from smoke in their planning and application. In 
addition the plan must include smoke management programs that include 
all necessary components including, but not limited to, actions to 
minimize emissions, evaluation of smoke dispersion, alternatives to 
fire, public notification, air quality monitoring, surveillance and 
enforcement, and program evaluation.
    (ii) A statewide inventory and emissions tracking system (spatial 
and temporal) of VOC, NOX, elemental and

[[Page 209]]

organic carbon, and fine particle emissions from fire. In reporting and 
tracking emissions from fire from within the State, States may use 
information from regional data-gathering and tracking initiatives.
    (iii) Identification and removal wherever feasible of any 
administrative barriers to the use of alternatives to burning in 
Federal, State, and private prescribed fire programs within the State.
    (iv) Enhanced smoke management programs for fire that consider 
visibility effects, not only health and nuisance objectives, and that 
are based on the criteria of efficiency, economics, law, emission 
reduction opportunities, land management objectives, and reduction of 
visibility impact.
    (v) Establishment of annual emission goals for fire, excluding 
wildfire, that will minimize emission increases from fire to the maximum 
extent feasible and that are established in cooperation with States, 
tribes, Federal land management agencies, and private entities.
    (7) Area sources of dust emissions from paved and unpaved roads. The 
plan must include an assessment of the impact of dust emissions from 
paved and unpaved roads on visibility conditions in the 16 Class I 
Areas. If such dust emissions are determined to be a significant 
contributor to visibility impairment in the 16 Class I areas, the State 
must implement emissions management strategies to address the impact as 
necessary and appropriate.
    (8) Pollution prevention. The plan must provide for:
    (i) An initial summary of all pollution prevention programs 
currently in place, an inventory of all renewable energy generation 
capacity and production in use, or planned as of the year 2002 
(expressed in megawatts and megawatt-hours), the total energy generation 
capacity and production for the State, the percent of the total that is 
renewable energy, and the State's anticipated contribution toward the 
renewable energy goals for 2005 and 2015, as provided in paragraph 
(d)(8)(vi) of this section.
    (ii) Programs to provide incentives that reward efforts that go 
beyond compliance and/or achieve early compliance with air-pollution 
related requirements.
    (iii) Programs to preserve and expand energy conservation efforts.
    (iv) The identification of specific areas where renewable energy has 
the potential to supply power where it is now lacking and where 
renewable energy is most cost-effective.
    (v) Projections of the short- and long-term emissions reductions, 
visibility improvements, cost savings, and secondary benefits associated 
with the renewable energy goals, energy efficiency and pollution 
prevention activities.
    (vi) A description of the programs relied on to achieve the State's 
contribution toward the Commission's goal that renewable energy will 
comprise 10 percent of the regional power needs by 2005 and 20 percent 
by 2015, and a demonstration of the progress toward achievement of the 
renewable energy goals in the years 2003, 2008, 2013, and 2018. This 
description must include documentation of the potential for renewable 
energy resources, the percentage of renewable energy associated with new 
power generation projects implemented or planned, and the renewable 
energy generation capacity and production in use and planned in the 
State. To the extent that it is not feasible for a State to meet its 
contribution to the regional renewable energy goals, the State must 
identify in the progress reports the measures implemented to achieve its 
contribution and explain why meeting the State's contribution was not 
feasible.
    (9) Implementation of additional recommendations. The plan must 
provide for implementation of all other recommendations in the 
Commission report that can be practicably included as enforceable 
emission limits, schedules of compliance, or other enforceable measures 
(including economic incentives) to make reasonable progress toward 
remedying existing and preventing future regional haze in the 16 Class I 
areas. The State must provide a report to EPA and the public in 2003, 
2008, 2013, and 2018 on the progress toward developing and implementing 
policy or strategy options recommended in the Commission Report.
    (10) Periodic implementation plan revisions. Each Transport Region 
State must submit to the Administrator periodic reports in the years 
2008, 2013, and

[[Page 210]]

2018. The progress reports must be in the form of implementation plan 
revisions that comply with the procedural requirements of Sec. 51.102 
and Sec. 51.103.
    (i) The report will assess the area for reasonable progress as 
provided in this section for mandatory Class I Federal area(s) located 
within the State and for mandatory Class I Federal area(s) located 
outside the State which may be affected by emissions from within the 
State. This demonstration may be based on assessments conducted by the 
States and/or a regional planning body. The progress reports must 
contain at a minimum the following elements:
    (A) A description of the status of implementation of all measures 
included in the implementation plan for achieving reasonable progress 
goals for mandatory Class I Federal areas both within and outside the 
State.
    (B) A summary of the emissions reductions achieved throughout the 
State through implementation of the measures described in paragraph 
(d)(10)(i)(A) of this section.
    (C) For each mandatory Class I Federal area within the State, an 
assessment of the following: the current visibility conditions for the 
most impaired and least impaired days; the difference between current 
visibility conditions for the most impaired and least impaired days and 
baseline visibility conditions; the change in visibility impairment for 
the most impaired and least impaired days over the past 5 years.
    (D) An analysis tracking the change over the past 5 years in 
emissions of pollutants contributing to visibility impairment from all 
sources and activities within the State. Emissions changes should be 
identified by type of source or activity. The analysis must be based on 
the most recent updated emissions inventory, with estimates projected 
forward as necessary and appropriate, to account for emissions changes 
during the applicable 5-year period.
    (E) An assessment of any significant changes in anthropogenic 
emissions within or outside the State that have occurred over the past 5 
years that have limited or impeded progress in reducing pollutant 
emissions and improving visibility.
    (F) An assessment of whether the current implementation plan 
elements and strategies are sufficient to enable the State, or other 
States with mandatory Federal Class I areas affected by emissions from 
the State, to meet all established reasonable progress goals.
    (G) A review of the State's visibility monitoring strategy and any 
modifications to the strategy as necessary.
    (ii) At the same time the State is required to submit any 5-year 
progress report to EPA in accordance with paragaph (d)(10)(i) of this 
section, the State must also take one of the following actions based 
upon the information presented in the progress report:
    (A) If the State determines that the existing implementation plan 
requires no further substantive revision at this time in order to 
achieve established goals for visibility improvement and emissions 
reductions, the State must provide to the Administrator a negative 
declaration that further revision of the existing implementation plan is 
not needed at this time.
    (B) If the State determines that the implementation plan is or may 
be inadequate to ensure reasonable progress due to emissions from 
sources in another State(s) which participated in a regional planning 
process, the State must provide notification to the Administrator and to 
the other State(s) which participated in the regional planning process 
with the States. The State must also collaborate with the other State(s) 
through the regional planning process for the purpose of developing 
additional strategies to address the plan's deficiencies.
    (C) Where the State determines that the implementation plan is or 
may be inadequate to ensure reasonable progress due to emissions from 
sources in another country, the State shall provide notification, along 
with available information, to the Administrator.
    (D) Where the State determines that the implementation plan is or 
may be inadequate to ensure reasonable progress due to emissions from 
within the State, the State shall develop additional strategies to 
address the plan deficiencies and revise the implementation plan no 
later than one year from

[[Page 211]]

the date that the progress report was due.
    (11) State planning and interstate coordination. In complying with 
the requirements of this section, States may include emission reductions 
strategies that are based on coordinated implementation with other 
States. Examples of these strategies include economic incentive programs 
and transboundary emissions trading programs. The implementation plan 
must include documentation of the technical and policy basis for the 
individual State apportionment (or the procedures for apportionment 
throughout the trans-boundary region), the contribution addressed by the 
State's plan, how it coordinates with other State plans, and compliance 
with any other appropriate implementation plan approvability criteria. 
States may rely on the relevant technical, policy and other analyses 
developed by a regional entity (such as the Western Regional Air 
Partnership) in providing such documentation. Conversely, States may 
elect to develop their own programs without relying on work products 
from a regional entity.
    (12) Tribal implementation. Consistent with 40 CFR Part 49, tribes 
within the Transport Region may implement the required visibility 
programs for the 16 Class I areas, in the same manner as States, 
regardless of whether such tribes have participated as members of a 
visibility transport commission.
    (e) States electing not to implement the commission recommendations. 
Any Transport Region State may elect not to implement the Commission 
recommendations set forth in paragraph (d) of this section. Such States 
are required to comply with the timelines and requirements of 
Sec. 51.308. Any Transport Region State electing not to implement the 
Commission recommendations must advise the other States in the Transport 
Region of the nature of the program and the effect of the program on 
visibility-impairing emissions, so that other States can take this 
information into account in developing programs under this section.
    (f) Annex to the Commission Report. (1) A Transport Region State may 
choose to comply with the provisions of this section and by doing so 
shall satisfy the requirements of Sec. 51.308(b) through (e) only if the 
Grand Canyon Visibility Transport Commission (or a regional planning 
body formed to implement the Commission recommendations) submits a 
satisfactory annex to the Commission Report no later than October 1, 
2000. To be satisfactory, the Annex must contain the following elements:
    (i) The annex must contain quantitative emission reduction 
milestones for stationary source sulfur dioxide emissions for the 
reporting years 2003, 2008, 2013 and 2018. The milestones must provide 
for steady and continuing emission reductions for the 2003-2018 time 
period consistent with the Commission's definition of reasonable 
progress, its goal of 50 to 70 percent reduction in sulfur dioxide 
emissions from 1990 actual emission levels by 2040, applicable 
requirements under the CAA, and the timing of implementation plan 
assessments of progress and identification of deficiencies which will be 
due in the years 2008, 2013, and 2018. The emission reduction milestones 
must be shown to provide for greater reasonable progress than would be 
achieved by application of best available retrofit technology (BART) 
pursuant to Sec. 51.308(e)(2) and would be approvable in lieu of BART.
    (ii) The annex must contain documentation of the market trading 
program or other programs to be implemented pursuant to paragraph (d)(4) 
of this section if current programs and voluntary measures are not 
sufficient to meet the required emission reduction milestones. This 
documentation must include model rules, memoranda of understanding, and 
other documentation describing in detail how emission reduction progress 
will be monitored, what conditions will require the market trading 
program to be activated, how allocations will be performed, and how the 
program will operate.
    (2) The Commission may elect, at the same time it submits the annex, 
to make recommendations intended to demonstrate reasonable progress for 
other mandatory Class I areas (beyond the original 16) within the 
Transport Region States, including the technical and policy 
justification for these additional mandatory Class I Federal areas

[[Page 212]]

in accordance with the provisions of paragraph (g) of this section.
    (3) The EPA will publish the annex upon receipt. If EPA finds that 
the annex meets the requirements of paragraph (f)(1) of this section and 
assures reasonable progress, then, after public notice and comment, will 
amend the requirements of paragraph (d)(4) of this section to 
incorporate the provisions of the annex within 1 year after EPA receives 
the annex. If EPA finds that the annex does not meet the requirements of 
paragraph (f)(1) of this section, or does not assure reasonable 
progress, or if EPA finds that the annex is not received, then each 
Transport Region State must submit an implementation plan for regional 
haze meeting all of the requirements of Sec. 51.308.
    (4) In accordance with the provisions under paragraph (f)(1) of this 
section, the annex may include a geographic enhancement to the program 
provided for in paragraph (d)(4) of this section to address the 
requirement under Sec. 51.302(c) related to Best Available Retrofit 
Technology for reasonably attributable impairment from the pollutants 
covered by the milestones or the backstop market trading program. The 
geographic enhancement program may include an appropriate level of 
reasonably attributable impairment which may require additional emission 
reductions over and above those achieved under the milestones defines in 
paragraph (f)(1)(i) of this section.
    (g) Additional Class I areas. The following submittals must be made 
by Transport Region States implementing the provisions of this section 
as the basis for demonstrating reasonable progress for additional Class 
I areas in the Transport Region States. If a Transport Region State 
submits an implementation plan which is approved by EPA as meeting the 
requirements of this section, it will be deemed to comply with the 
requirements for reasonable progress for the period from approval of the 
plan to 2018.
    (1) In the plan submitted for the 16 Class I areas no later than 
December 31, 2003, a declaration indicating whether other Class I areas 
will be addressed under Sec. 51.308 or paragraphs (g)(2) and (3) of this 
section.
    (2) In a plan submitted no later than December 31, 2008, provide a 
demonstration of expected visibility conditions for the most impaired 
and least impaired days at the additional mandatory Class I Federal 
area(s) based on emissions projections from the long-term strategies in 
the implementation plan. This demonstration may be based on assessments 
conducted by the States and/or a regional planning body.
    (3) In a plan submitted no later than December 31, 2008, provide 
revisions to the plan submitted under paragraph (c) of this section, 
including provisions to establish reasonable progress goals and 
implement any additional measures necessary to demonstrate reasonable 
progress for the additional mandatory Federal Class I areas. These 
revisions must comply with the provisions of Sec. 51.308(d)(1) through 
(4).
    (4) The following provisions apply for Transport Region States 
establishing reasonable progress goals and adopting any additional 
measures for Class I areas other than the 16 Class I areas under 
paragraphs (g)(2) and (3) of this section.
    (i) In developing long-term strategies pursuant to 
Sec. 51.308(d)(3), the State may build upon the strategies implemented 
under paragraph (d) of this section, and take full credit for the 
visibility improvement achieved through these strategies.
    (ii) The requirement under Sec. 51.308(e) related to Best Available 
Retrofit Technology for regional haze is deemed to be satisfied for 
pollutants addressed by the milestones and backstop trading program if, 
in establishing the emission reductions milestones under paragraph (f) 
of this section, it is shown that greater reasonable progress will be 
achieved for these Class I areas than would be achieved through the 
application of source-specific BART emission limitations under 
Sec. 51.308(e)(1).
    (iii) The Transport Region State may consider whether any strategies 
necessary to achieve the reasonable progress goals required by paragraph 
(g)(3) of this section are incompatible with the strategies implemented 
under paragraph (d) of this section to the extent the State adequately 
demonstrates that the incompatibility is related to the costs of the 
compliance,

[[Page 213]]

the time necessary for compliance, the energy and no air quality 
environmental impacts of compliance, or the remaining useful life of any 
existing source subject to such requirements.

[64 FR 35769, July 1, 1999]



                           Subpart Q--Reports

    Authority: Secs. 110, 301(a), 313, 319, Clean Air Act (42 U.S.C. 
7410, 7601(a), 7613, 7619).

    Source: 44 FR 27569, May 10, 1979, unless otherwise noted.

                       Air Quality Data Reporting



Sec. 51.320  Annual air quality data report.

    The requirements for reporting air quality data collected for 
purposes of the plan are located in subpart C of part 58 of this 
chapter.

               Source Emissions and State Action Reporting



Sec. 51.321  Annual source emissions and State action report.

    On an annual (calendar year) basis beginning with calendar year 
1979, the State agency shall report to the Administrator (through the 
appropriate Regional Office) information as specified in Secs. 51.323 
through 51.326. Reports must be submitted by July 1 of each year for 
data collected and actions which took place during the period January 1 
to December 31 of the previous year.



Sec. 51.322  Sources subject to emissions reporting.

    (a) Point sources subject to the annual emissions reporting 
requirements of Sec. 51.321 are defined as follows:
    (1) For particulate matter, PM10, sulfur oxides, VOC and 
nitrogen oxides, any facility that actually emits a total of 181.4 
metric tons (200 tons) per year or more of any one pollutant. For 
particulate matter emissions, the reporting requirement ends with the 
reporting of calendar year 1987 emissions. For PM10 
emissions, the reporting requirement begins with the reporting of 
calendar year 1988 emissions.
    (2) For carbon monoxide, any facility that actually emits a total of 
1814 metric tons (2000 tons) per year or more.
    (3) For lead or lead compounds measured as elemental lead, any 
facility that actually emits a total of 4.5 metric tons (5 tons) per 
year or more.
    (b) Annual emissions reporting requirements apply only to emissions 
of each pollutant from any individual emission point within the facility 
that emits:
    (1) For particulate matter, PM10, sulfur oxides, VOC and 
nitrogen oxides. 22.7 metric tons (25 tons) per year or more. For 
particulate matter, the reporting requirement ends with the reporting of 
calendar year 1987 emissions. For PM10, the reporting 
requirement begins with the reporting of calendar year 1988 emissions.
    (2) For carbon monoxide, 227 metric tons (250 tons) per year or 
more.
    (3) For lead or lead compounds measured as elemental lead, 4.5 
metric tons (5 tons) per year or more.

[44 FR 27569, May 10, 1979, as amended at 44 FR 65070, Nov. 9, 1979; 52 
FR 24714, July 1, 1987; 64 FR 7462, Feb. 12, 1999]



Sec. 51.323  Reportable emissions data and information.

    (a) The State shall submit in the annual report the following 
emissions data and information:
    (1) Emissions of particulate matter (PM10), sulfur oxides, carbon 
monoxide, nitrogen oxides, VOC and lead or lead compounds measured as 
elemental lead as specified by the AIRS Facility Subsystem User's Guide 
AF2 ``AFS Data Coding'' (EPA-454/B-94-004) point source coding form,
    (2) [Reserved]
    (3) Emissions of PM 2.5 as will be specified in a future guideline.
    (b) Such emissions data and information specified in paragraph (a) 
of this section must be submitted to the AIRS/AFS database via either 
online data entry or batch update system.
    (c) The emissions data and information specified by paragraph (a) of 
this section must be submitted in the annual report for any point source 
for which one or more of the following conditions occurs:
    (1) A source achieves compliance at any time within the reporting 
period with any regulation of an applicable plan,

[[Page 214]]

    (2) A new or modified source receives approval to construct during 
the reporting period or begins operating during the reporting period,
    (3) A source ceases operations during the reporting period, or
    (4) A source's emissions have changed more than 5% from the most 
recently submitted emissions data.
    (d) If, as determined by the State and the Regional Administrator, 
the emissions from any point source have not changed more than 5% from 
the most recently submitted emissions data, the State shall update the 
year of record of the previously reported data and information specified 
by paragraph (a) of this section.

[44 FR 27569, May 10, 1979, as amended at 52 FR 24714, July 1, 1987; 64 
FR 7463, Feb. 12, 1999]



Sec. 51.324  Progress in plan enforcement.

    (a) For each point source, the State shall report any achievement 
made during the reporting period of any increment of progress of 
compliance schedules required by:
    (1) The applicable plan, or
    (2) Any enforcement order or other State action required to be 
submitted pursuant to Sec. 51.327.
    (b) For each point source, the State shall report any enforcement 
action taken during the reporting period and not submitted under 
Sec. 51.327 which results in civil or criminal penalties.



Sec. 51.326  Reportable revisions.

    The State shall identify and describe all substantive plan revisions 
during the reporting period of the applicable plan other than revisions 
to rules and regulations or compliance schedules submitted in accordance 
with Sec. 51.6(d). Substantive revisions shall include but are not 
limited to changes in stack-test procedures for determining compliance 
with applicable regulations, modifications in the projected total 
manpower needs to carry out the approved plan, and all changes in 
responsibilities given to local agencies to carry out various portions 
of the plan.



Sec. 51.327  Enforcement orders and other State actions.

    (a) Any State enforcement order, including any State court order, 
must be submitted to the Administrator within 60 days of its issuance or 
adoption by the State.
    (b) A State enforcement order or other State action must be 
submitted as a revision to the applicable implementation plan pursuant 
to Sec. 51.104 and approved by the Administrator in order to be 
considered a revision to such plan.

[36 FR 22398, Nov. 25, 1971, as amended at 51 FR 40675, Nov. 7, 1986]



Sec. 51.328  [Reserved]



                          Subpart R--Extensions



Sec. 51.341  Request for 18-month extension.

    (a) Upon request of the State made in accordance with this section, 
the Administrator may, whenever he determines necessary, extend, for a 
period not to exceed 18 months, the deadline for submitting that portion 
of a plan that implements a secondary standard.
    (b) Any such request must show that attainment of the secondary 
standards will require emission reductions exceeding those which can be 
achieved through the application of reasonably available control 
technology.
    (c) Any such request for extension of the deadline with respect to 
any State's portion of an interstate region must be submitted jointly 
with requests for such extensions from all other States within the 
region or must show that all such States have been notified of such 
request.
    (d) Any such request must be submitted sufficiently early to permit 
development of a plan prior to the deadline in the event that such 
request is denied.

[51 FR 40675, Nov. 7, 1986]



         Subpart S--Inspection/Maintenance Program Requirements

    Source: 57 FR 52987, Nov. 5, 1992, unless otherwise noted.



Sec. 51.350  Applicability.

    Inspection/maintenance (I/M) programs are required in both ozone and 
carbon monoxide (CO) nonattainment areas, depending upon population and

[[Page 215]]

nonattainment classification or design value.
    (a) Nonattainment area classification and population criteria. (1) 
States or areas within an ozone transport region shall implement 
enhanced I/M programs in any metropolitan statistical area (MSA), or 
portion of an MSA, within the State or area with a 1990 population of 
100,000 or more as defined by the Office of Management and Budget (OMB) 
regardless of the area's attainment classification. In the case of a 
multi-state MSA, enhanced I/M shall be implemented in all ozone 
transport region portions if the sum of these portions has a population 
of 100,000 or more, irrespective of the population of the portion in the 
individual ozone transport region State or area.
    (2) Apart from those areas described in paragraph (a)(1) of this 
section, any area classified as serious or worse ozone nonattainment, or 
as moderate or serious CO nonattainment with a design value greater than 
12.7 ppm, and having a 1980 Bureau of Census-defined (Census-defined) 
urbanized area population of 200,000 or more, shall implement enhanced 
I/M in the 1990 Census-defined urbanized area.
    (3) Any area classified, as of November 5, 1992, as marginal ozone 
nonattainment or moderate CO nonattainment with a design value of 12.7 
ppm or less shall continue operating I/M programs that were part of an 
approved State Implementation Plan (SIP) as of November 15, 1990, and 
shall update those programs as necessary to meet the basic I/M program 
requirements of this subpart. Any such area required by the Clean Air 
Act, as in effect prior to November 15, 1990, as interpreted in EPA 
guidance, to have an I/M program shall also implement a basic I/M 
program. Serious, severe and extreme ozone areas and CO areas over 12.7 
ppm shall also continue operating existing I/M programs and shall 
upgrade such programs, as appropriate, pursuant to this subpart.
    (4) Any area classified as moderate ozone nonattainment, and not 
required to implement enhanced I/M under paragraph (a)(1) of this 
section, shall implement basic I/M in any 1990 Census-defined urbanized 
area with a population of 200,000 or more.
    (5) [Reserved]
    (6) If the boundaries of a moderate ozone nonattainment area are 
changed pursuant to section 107(d)(4)(A)(i)-(ii) of the Clean Air Act, 
such that the area includes additional urbanized areas with a population 
of 200,000 or more, then a basic I/M program shall be implemented in 
these additional urbanized areas.
    (7) If the boundaries of a serious or worse ozone nonattainment area 
or of a moderate or serious CO nonattainment area with a design value 
greater than 12.7 ppm are changed any time after enactment pursuant to 
section 107(d)(4)(A) such that the area includes additional urbanized 
areas, then an enhanced I/M program shall be implemented in the newly 
included 1990 Census-defined urbanized areas, if the 1980 Census-defined 
urban area population is 200,000 or more.
    (8) If a marginal ozone nonattainment area, not required to 
implement enhanced I/M under paragraph (a)(1) of this section, is 
reclassified to moderate, a basic I/M program shall be implemented in 
the 1990 Census-defined urbanized area(s) with a population of 200,000 
or more. If the area is reclassified to serious or worse, an enhanced I/
M program shall be implemented in the 1990 Census-defined urbanized 
area, if the 1980 Census-defined urban area population is 200,000 or 
more.
    (9) If a moderate ozone or CO nonattainment area is reclassified to 
serious or worse, an enhanced I/M program shall be implemented in the 
1990 Census-defined urbanized area, if the 1980 Census-defined 
population is 200,000 or more.
    (b) Extent of area coverage. (1) In an ozone transport region, the 
program shall cover all counties within subject MSAs or subject portions 
of MSAs, as defined by OMB in 1990, except largely rural counties having 
a population density of less than 200 persons per square mile based on 
the 1990 Census and counties with less than 1% of the population in the 
MSA may be excluded provided that at least 50% of the MSA population is 
included in the program. This provision does not preclude the voluntary 
inclusion of portions of an excluded county. Non-urbanized islands not 
connected to the mainland by

[[Page 216]]

roads, bridges, or tunnels may be excluded without regard to population.
    (2) Outside of ozone transport regions, programs shall nominally 
cover at least the entire urbanized area, based on the 1990 census. 
Exclusion of some urban population is allowed as long as an equal number 
of non-urban residents of the MSA containing the subject urbanized area 
are included to compensate for the exclusion.
    (3) Emission reduction benefits from expanding coverage beyond the 
minimum required urban area boundaries can be applied toward the 
reasonable further progress requirements or can be used for offsets, 
provided the covered vehicles are operated in the nonattainment area, 
but not toward the enhanced I/M performance standard requirement.
    (4) In a multi-state urbanized area with a population of 200,000 or 
more that is required under paragraph (a) of this section to implement 
I/M, any State with a portion of the area having a 1990 Census-defined 
population of 50,000 or more shall implement an I/M program. The other 
coverage requirements in paragraph (b) of this section shall apply in 
multi-state areas as well.
    (5) Notwithstanding the limitation in paragraph (b)(3) of this 
section, in an ozone transport region, States which opt for a program 
which meets the performance standard described in Sec. 51.351(h) and 
claim in their SIP less emission reduction credit than the basic 
performance standard for one or more pollutants, may apply a geographic 
bubble covering areas in the State not otherwise subject to an I/M 
requirement to achieve emission reductions from other measures equal to 
or greater than what would have been achieved if the low enhanced 
performance standard were met in the subject I/M areas. Emissions 
reductions from non-I/M measures shall not be counted towards the OTR 
low enhanced performance standard.
    (c) Requirements after attainment. All I/M programs shall provide 
that the program will remain effective, even if the area is redesignated 
to attainment status, until the State submits and EPA approves a 
maintenance plan, under section 175A, which convincingly demonstrates 
that the area can maintain the relevant standard for the maintenance 
period without benefit of the emission reductions attributable to the I/
M program. The State shall commit to fully implement and enforce the 
program throughout such period, and, at a minimum, for the purposes of 
SIP approval, legislation authorizing the program shall not sunset prior 
to the attainment deadline.
    (d) SIP requirements. The SIP shall describe the applicable areas in 
detail and, consistent with Sec. 51.372 of this subpart, shall include 
the legal authority or rules necessary to establish program boundaries.

[57 FR 52987, Nov. 5, 1992, as amended at 60 FR 48034, Sept. 18, 1995; 
61 FR 39036, July 25, 1996]



Sec. 51.351  Enhanced I/M performance standard.

    (a) Enhanced I/M programs shall be designed and implemented to meet 
or exceed a minimum performance standard, which is expressed as emission 
levels in area-wide average grams per mile (gpm), achieved from highway 
mobile sources as a result of the program. The emission levels achieved 
by the State's program design shall be calculated using the most current 
version, at the time of submittal, of the EPA mobile source emission 
factor model or an alternative model approved by the Administrator, and 
shall meet the minimum performance standard both in operation and for 
SIP approval. Areas shall meet the performance standard for the 
pollutants which cause them to be subject to enhanced I/M requirements. 
In the case of ozone nonattainment areas subject to enhanced I/M and 
subject areas in the Ozone Transport Region, the performance standard 
must be met for both oxides of nitrogen (NOX) and volatile 
organic compounds (VOCs), except as provided in paragraph (d) of this 
section.
    (1) Network type. Centralized testing.
    (2) Start date. For areas with existing I/M programs, 1983. For 
areas newly subject, 1995.
    (3) Test frequency. Annual testing.
    (4) Model year coverage. Testing of 1968 and later vehicles.
    (5) Vehicle type coverage. Light duty vehicles, and light duty 
trucks, rated

[[Page 217]]

up to 8,500 pounds Gross Vehicle Weight Rating (GVWR).
    (6) Exhaust emission test type. Transient mass-emission testing on 
1986 and later model year vehicles using the IM240 driving cycle, two-
speed testing (as described in appendix B of this subpart S) of 1981-
1985 vehicles, and idle testing (as described in appendix B of this 
subpart S) of pre-1981 vehicles is assumed.
    (7) Emission standards. (i) Emission standards for 1986 through 1993 
model year light duty vehicles, and 1994 and 1995 light-duty vehicles 
not meeting Tier 1 emission standards, of 0.80 gpm hydrocarbons (HC), 20 
gpm CO, and 2.0 gpm NOX;
    (ii) Emission standards for 1986 through 1993 light duty trucks less 
than 6000 pounds gross vehicle weight rating (GVWR), and 1994 and 1995 
trucks not meeting Tier 1 emission standards, of 1.2 gpm HC, 20 gpm CO, 
and 3.5 gpm NOX;
    (iii) Emission standards for 1986 through 1993 light duty trucks 
greater than 6000 pounds GVWR, and 1994 and 1995 trucks not meeting Tier 
1 emission standards, of 1.2 gpm HC, 20 gpm CO, and 3.5 gpm 
NOX;
    (iv) Emission standards for 1994 and later light duty vehicles 
meeting Tier 1 emission standards of 0.70 gpm HC, 15 gpm CO, and 1.4 gpm 
NOX;
    (v) Emission standards for 1994 and later light duty trucks under 
6000 pounds GVWR and meeting Tier 1 emission standards of 0.70 gpm HC, 
15 gpm CO and 2.0 gpm NOX;
    (vi) Emission standards for 1994 and later light duty trucks greater 
than 6000 pounds GVWR and meeting Tier 1 emission standards of 0.80 gpm 
HC, 15 gpm CO and 2.0 gpm NOX;
    (vii) Emission standards for 1981-1985 model year vehicles of 1.2% 
CO, and 220 ppm HC for the idle, two-speed tests and loaded steady-state 
tests (as described in appendix B of this subpart S); and
    (viii) Maximum exhaust dilution measured as no less than 6% CO plus 
carbon dioxide (CO2) on vehicles subject to a steady-state 
test (as described in appendix B of this subpart S).
    (8) Emission control device inspections. Visual inspection of the 
catalyst and fuel inlet restrictor on all 1984 and later model year 
vehicles.
    (9) Evaporative system function checks. Evaporative system integrity 
(pressure) test on 1983 and later model year vehicles and an evaporative 
system transient purge test on 1986 and later model year vehicles.
    (10) Stringency. A 20% emission test failure rate among pre-1981 
model year vehicles.
    (11) Waiver rate. A 3% waiver rate, as a percentage of failed 
vehicles.
    (12) Compliance rate. A 96% compliance rate.
    (13) Evaluation date. Enhanced I/M programs shall be shown to obtain 
the same or lower emission levels as the model program by 2000 for ozone 
nonattainment areas and 2001 for CO nonattainment areas, and for severe 
and extreme ozone nonattainment areas, on each applicable milestone and 
attainment deadline, thereafter. Milestones for NOX shall be 
the same as for ozone.
    (b) On-road testing. The performance standard shall include on-road 
testing of at least 0.5% of the subject vehicle population, or 20,000 
vehicles whichever is less, as a supplement to the periodic inspection 
required in paragraphs (f) and (g) of this section. Specific 
requirements are listed in Sec. 51.371 of this subpart.
    (c) On-board diagnostics (OBD). The performance standard shall 
include inspection of all 1996 and later light-duty vehicles and light-
duty trucks equipped with certified on-board diagnostic systems, and 
repair of malfunctions or system deterioration identified by or 
affecting OBD systems as specified in Sec. 51.357.
    (d) Modeling requirements. Equivalency of the emission levels which 
will be achieved by the I/M program design in the SIP to those of the 
model program described in this section shall be demonstrated using the 
most current version of EPA's mobile source emission model, or an 
alternative approved by the Administrator, using EPA guidance to aid in 
the estimation of input parameters. States may adopt alternative 
approaches that meet this performance standard. States may do so through 
program design changes that affect normal I/M input parameters to the 
mobile source emission factor

[[Page 218]]

model, or through program changes (such as the accelerated retirement of 
high emitting vehicles) that reduce in-use mobile source emissions. If 
the Administrator finds, under section 182(b)(1)(A)(i) of the Act 
pertaining to reasonable further progress demonstrations or section 
182(f)(1) of the Act pertaining to provisions for major stationary 
sources, that NOX emission reductions are not beneficial in a 
given ozone nonattainment area, then NOX emission reductions 
are not required of the enhanced I/M program, but the program shall be 
designed to offset NOX increases resulting from the repair of 
HC and CO failures.
    (e) [Reserved]
    (f) High Enhanced Performance Standard. Except as provided in 
paragraph (g) of this section, the model program elements for the 
enhanced I/M performance standard shall be as follows:
    (1) Network type. Centralized testing.
    (2) Start date. For areas with existing I/M programs, 1983. For 
areas newly subject, 1995.
    (3) Test frequency. Annual testing.
    (4) Model year coverage. Testing of 1968 and later vehicles.
    (5) Vehicle type coverage. Light duty vehicles, and light duty 
trucks, rated up to 8,500 pounds Gross Vehicle Weight Rating (GVWR).
    (6) Exhaust emission test type. Transient mass-emission testing on 
1986 and later model year vehicles using the IM240 driving cycle, two-
speed testing (as described in appendix B of this subpart S) of 1981-
1985 vehicles, and idle testing (as described in appendix B of this 
subpart S) of pre-1981 vehicles is assumed.
    (7) Emission standards. (i) Emission standards for 1986 through 1993 
model year light duty vehicles, and 1994 and 1995 light-duty vehicles 
not meeting Tier 1 emission standards, of 0.80 gpm hydrocarbons (HC), 20 
gpm CO, and 2.0 gpm NOX;
    (ii) Emission standards for 1986 through 1993 light duty trucks less 
than 6000 pounds gross vehicle weight rating (GVWR), and 1994 and 1995 
trucks not meeting Tier 1 emission standards, of 1.2 gpm HC, 20 gpm CO, 
and 3.5 gpm NOX;
    (iii) Emission standards for 1986 through 1993 light duty trucks 
greater than 6000 pounds GVWR, and 1994 and 1995 trucks not meeting the 
Tier 1 emission standards, of 1.2 gpm HC, 20 gpm CO, and 3.5 gpm 
NOX;
    (iv) Emission standards for 1994 and later light duty vehicles 
meeting Tier 1 emission standards of 0.70 gpm HC, 15 gpm CO, and 1.4 gpm 
NOX;
    (v) Emission standards for 1994 and later light duty trucks under 
6000 pounds GVWR and meeting Tier 1 emission standards of 0.70 gpm HC, 
15 gpm CO, and 2.0 gpm NOX;
    (vi) Emission standards for 1994 and later light duty trucks greater 
than 6000 pounds GVWR and meeting Tier 1 emission standards of 0.80 gpm 
HC, 15 gpm CO and 2.5 gpm NOX;
    (vii) Emission standards for 1981-1985 model year vehicles of 1.2% 
CO, and 220 gpm HC for the idle, two-speed tests and loaded steady-state 
tests (as described in appendix B of this subpart S); and
    (viii) Maximum exhaust dilution measured as no less than 6% CO plus 
carbon dioxide (CO2) on vehicles subject to a steady-state 
test (as described in appendix B of this subpart S); and
    (viii) Maximum exhaust dilution measured as no less than 6% CO plus 
carbon dioxide (CO2) on vehicles subject to a steady-state 
test (as described in appendix B of this subpart S).
    (8) Emission control device inspections. (i) Visual inspection of 
the catalyst and fuel inlet restrictor on all 1984 and later model year 
vehicles.
    (ii) Visual inspection of the positive crankcase ventilation valve 
on 1968 through 1971 model years, inclusive, and of the exhaust gas 
recirculation valve on 1972 through 1983 model year vehicles, inclusive.
    (9) Evaporative system function checks. Evaporative system integrity 
(pressure) test on 1983 and later model year vehicles and an evaporative 
system transient purge test on 1986 and later model year vehicles.
    (10) Stringency. A 20% emission test failure rate among pre-1981 
model year vehicles.
    (11) Waiver rate. A 3% waiver rate, as a percentage of failed 
vehicles.
    (12) Compliance rate. A 96% compliance rate.
    (13) Evaluation date. Enhanced I/M program areas shall be shown to 
obtain

[[Page 219]]

the same or lower emission levels as the model program described in this 
paragraph by 2000 for ozone nonattainment areas and 2001 for CO 
nonattainment areas, and for severe and extreme ozone nonattainment 
areas, on each applicable milestone and attainment deadline, thereafter. 
Milestones for NOX shall be the same as for ozone.
    (g) Alternate Low Enhanced I/M Performance Standard. An enhanced I/M 
area which is either not subject to or has an approved State 
Implementation Plan pursuant to the requirements of the Clean Air Act 
Amendments of 1990 for Reasonable Further Progress in 1996, and does not 
have a disapproved plan for Reasonable Further Progress for the period 
after 1996 or a disapproved plan for attainment of the air quality 
standards for ozone or CO, may select the alternate low enhanced I/M 
performance standard described below in lieu of the standard described 
in paragraph (f) of this section. The model program elements for this 
alternate low enhanced I/M performance standard are:
    (1) Network type. Centralized testing.
    (2) Start date. For areas with existing I/M programs, 1983. For 
areas newly subject, 1995.
    (3) Test frequency. Annual testing.
    (4) Model year coverage. Testing of 1968 and newer vehicles.
    (5) Vehicle type coverage. Light duty vehicles, and light duty 
trucks, rated up to 8,500 pounds GVWR.
    (6) Exhaust emission test type. Idle testing of all covered vehicles 
(as described in appendix B of subpart S).
    (7) Emission standards. Those specified in 40 CFR part 85, subpart 
W.
    (8) Emission control device inspections. Visual inspection of the 
positive crankcase ventilation valve on all 1968 through 1971 model year 
vehicles, inclusive, and of the exhaust gas recirculation valve on all 
1972 and newer model year vehicles.
    (9) Evaporative system function checks. None.
    (10) Stringency. A 20% emission test failure rate among pre-1981 
model year vehicles.
    (11) Waiver rate. A 3% waiver rate, as a percentage of failed 
vehicles.
    (12) Compliance rate. A 96% compliance rate.
    (13) Evaluation date. Enhanced I/M program areas subject to the 
provisions of this paragraph shall be shown to obtain the same or lower 
emission levels as the model program described in this paragraph by 2000 
for ozone nonattainment areas and 2001 for CO nonattainment areas, and 
for severe and extreme ozone nonattainment areas, on each applicable 
milestone and attainment deadline, thereafter. Milestones for 
NOX shall be the same as for ozone.
    (h) Ozone Transport Region Low-Enhanced Performance Standard. An 
attainment area, marginal ozone area, or moderate ozone area with a 1980 
Census population of less than 200,000 in the urbanized area, in an 
ozone transport region, that is required to implement enhanced I/M under 
section 184(b)(1)(A) of the Clean Air Act, but was not previously 
required to or did not in fact implement basic I/M under the Clean Air 
Act as enacted prior to 1990 and is not subject to the requirements for 
basic I/M programs in this subpart, may select the performance standard 
described below in lieu of the standard described in paragraph (f) or 
(g) of this section as long as the difference in emission reductions 
between the program described in paragraph (g) and this paragraph are 
made up with other measures, as provided in Sec. 51.350(b)(5). 
Offsetting measures shall not include those otherwise required by the 
Clean Air Act in the areas from which credit is bubbled. The program 
elements for this alternate OTR enhanced I/M performance standard are:
    (1) Network type. Centralized testing.
    (2) Start date. January 1, 1999.
    (3) Test frequency. Annual testing.
    (4) Model year coverage. Testing of 1968 and newer vehicles.
    (5) Vehicle type coverage. Light duty vehicles, and light duty 
trucks, rated up to 8,500 pounds GVWR.
    (6) Exhaust emission test type. Remote sensing measurements on 1968-
1995 vehicles; on-board diagnostic system checks on 1996 and newer 
vehicles.
    (7) Emission standards. For remote sensing measurements, a carbon 
monoxide standard of 7.5% (with at least two separate readings above 
this level to establish a failure).

[[Page 220]]

    (8) Emission control device inspections. Visual inspection of the 
catalytic converter on 1975 and newer vehicles and visual inspection of 
the positive crankcase ventilation valve on 1968-1974 vehicles.
    (9) Waiver rate. A 3% waiver rate, as a percentage of failed 
vehicles.
    (10) Compliance rate. A 96% compliance rate.
    (11) Evaluation dates. Enhanced I/M program areas subject to the 
provisions of this paragraph shall be shown to obtain the same or lower 
VOC and NOX emission levels as the model program described in 
this paragraph by January 1, 2000, 2003, 2006, and 2007. Equality of 
substituted emission reductions to the benefits of the low enhanced 
performance standard must be demonstrated for the same evaluation dates.

[57 FR 52987, Nov. 5, 1992, as amended at 58 FR 59367, Nov. 9, 1993; 59 
FR 32343, June 23, 1994; 60 FR 48035, Sept. 18, 1995; 61 FR 39036, July 
25, 1996; 61 FR 40945, Aug. 6, 1996; 63 FR 24433, May 4, 1998]



Sec. 51.352  Basic I/M performance standard.

    (a) Basic I/M programs shall be designed and implemented to meet or 
exceed a minimum performance standard, which is expressed as emission 
levels achieved from highway mobile sources as a result of the program. 
The performance standard shall be established using the following model 
I/M program inputs and local characteristics, such as vehicle mix and 
local fuel controls. Similarly, the emission reduction benefits of the 
State's program design shall be estimated using the most current version 
of the EPA mobile source emission model, and shall meet the minimum 
performance standard both in operation and for SIP approval.
    (1) Network type. Centralized testing.
    (2) Start date. For areas with existing I/M programs, 1983. For 
areas newly subject, 1994.
    (3) Test frequency. Annual testing.
    (4) Model year coverage. Testing of 1968 and later model year 
vehicles.
    (5) Vehicle type coverage. Light duty vehicles.
    (6) Exhaust emission test type. Idle test.
    (7) Emission standards. No weaker than specified in 40 CFR part 85, 
subpart W.
    (8) Emission control device inspections. None.
    (9) Stringency. A 20% emission test failure rate among pre-1981 
model year vehicles.
    (10) Waiver rate. A 0% waiver rate.
    (11) Compliance rate. A 100% compliance rate.
    (12) Evaluation date. Basic I/M programs shall be shown to obtain 
the same or lower emission levels as the model inputs by 1997 for ozone 
nonattainment areas and 1996 for CO nonattainment areas; and, for 
serious or worse ozone nonattainment areas, on each applicable milestone 
and attainment deadline, thereafter.
    (b) Oxides of nitrogen. Basic I/M testing in ozone nonattainment 
areas shall be designed such that no increase in NOX 
emissions occurs as a result of the program. If the Administrator finds, 
under section 182(b)(1)(A)(i) of the Act pertaining to reasonable 
further progress demonstrations or section 182(f)(1) of the Act 
pertaining to provisions for major stationary sources, that 
NOX emission reductions are not beneficial in a given ozone 
nonattainment area, then the basic I/M NOX requirement may be 
omitted. States shall implement any required NOX controls 
within 12 months of implementation of the program deadlines required in 
Sec. 51.373 of this subpart, except that newly implemented I/M programs 
shall include NOX controls from the start.
    (c) On-board diagnostics (OBD). The performance standard shall 
include inspection of all 1996 and later light-duty vehicles and light-
duty trucks equipped with certified on-board diagnostic systems, and 
repair of malfunctions or system deterioration identified by or 
affecting OBD systems as specified in Sec. 51.357.
    (d) Modeling requirements. Equivalency of emission levels which will 
be achieved by the I/M program design in the SIP to those of the model 
program described in this section shall be demonstrated using the most 
current version of EPA's mobile source emission model and EPA guidance 
on the estimation of input parameters. Areas

[[Page 221]]

required to implement basic I/M programs shall meet the performance 
standard for the pollutants which cause them to be subject to basic 
requirements. Areas subject as a result of ozone nonattainment shall 
meet the standard for VOCs and shall demonstrate no NOX 
increase, as required in paragraph (b) of this section.

[57 FR 52987, Nov. 5, 1992, as amended at 61 FR 40945, Aug. 6, 1996; 63 
FR 24433, May 4, 1998]



Sec. 51.353  Network type and program evaluation.

    Enhanced I/M programs shall be operated in a centralized test-only 
format, unless the State can demonstrate that a decentralized program is 
equally effective in achieving the enhanced I/M performance standard. 
Basic I/M programs can be centralized, decentralized, or a hybrid at the 
State's discretion, but shall be demonstrated to achieve the same 
emission reduction as the program described in Sec. 51.352 of this 
subpart.
    (a) Presumptive equivalency. A decentralized network consisting of 
stations that only perform official I/M testing (which may include 
safety-related inspections) and in which owners and employees of those 
stations, or companies owning those stations, are contractually or 
legally barred from engaging in motor vehicle repair or service, motor 
vehicle parts sales, and motor vehicle sale and leasing, either directly 
or indirectly, and are barred from referring vehicle owners to 
particular providers of motor vehicle repair services (except as 
provided in Sec. 51.369(b)(1) of this subpart) shall be considered 
equivalent to a centralized, test-only system. States may allow such 
stations to engage in the sale of refreshments for the use of employees 
and customers waiting at the station and may fulfill other functions 
typically carried out by the State such as renewal of vehicle 
registration and driver's licenses, or tax and fee collections.
    (b) Case-by-case equivalency. (1) Credits for test-and-repair 
networks, i.e., those not meeting the requirements of paragraph (a) of 
this section, are assumed to be 50% less than those for a test-only 
network for the tailpipe emission test, purge test, evaporative system 
integrity test, catalyst check, and gas cap check; and 75% less for the 
evaporative canister checks, PCV check, and air system checks. Smaller 
reductions in credits for the various test protocols may be claimed if a 
State can demonstrate to the satisfaction of the Administrator that 
based on past performance with the specific test-type and inspection 
standards employed, its test-and-repair system will exceed these levels. 
At a minimum, such a demonstration shall include:
    (i) Surveys that assess the effectiveness of repairs performed on 
vehicles that failed the tailpipe emission test and evaporative system 
tests;
    (ii) In programs including tampering checks, measurement of actual 
tampering rates, their change over time, and the change attributable to 
finding and fixing such tampering as opposed to deterrence effects; and
    (iii) The results of undercover surveys of inspector effectiveness 
as it relates to identifying vehicles that need repair.
    (2) In the case of hybrid systems, which may be implemented in basic 
I/M areas, including both test-only and test-and-repair facilities, full 
credit shall apply to the portion of the fleet initially tested and 
subsequently retested at a test-only facility meeting the requirements 
of paragraph (a) of this section, and to the portion of the fleet 
initially tested and failed at a test-and-repair facility but 
subsequently passing a comprehensive retest at a test-only facility 
meeting those same requirements. The credit loss assumptions described 
in paragraph (b)(1) of this section shall apply to the portion of the 
fleet initially passed at a test-and-repair facility, and to the portion 
initially failed at a test-only facility and retested at a test-and-
repair facility.
    (3) Areas operating test-and-repair networks or hybrid networks may, 
in the future, claim greater effectiveness than described in paragraph 
(b)(1) of this section, if a demonstration of greater effectiveness is 
made to the satisfaction of the Administrator using the program 
evaluation protocol described in paragraph (c) of this section.
    (c) Program evaluation. Enhanced I/M programs shall include an 
ongoing

[[Page 222]]

evaluation to quantify the emission reduction benefits of the program, 
and to determine if the program is meeting the requirements of the Clean 
Air Act and this subpart.
    (1) The State shall report the results of the program evaluation on 
a biennial basis, starting two years after the initial start date of 
mandatory testing as required in Sec. 51.373 of this subpart.
    (2) The evaluation shall be considered in establishing actual 
emission reductions achieved from I/M for the purposes of satisfying the 
requirements of sections 182(g)(1) and 182(g)(2) of the Clean Air Act, 
relating to reductions in emissions and compliance demonstration.
    (3) The evaluation program shall consist, at a minimum, of those 
items described in paragraph (b)(1) of this section and program 
evaluation data using a sound evaluation methodology, as approved by 
EPA, and evaporative system checks, specified in Sec. 51.357(a) (9) and 
(10) of this subpart, for model years subject to those evaporative 
system test procedures. The test data shall be obtained from a 
representative, random sample, taken at the time of initial inspection 
(before repair) on a minimum of 0.1 percent of the vehicles subject to 
inspection in a given year. Such vehicles shall receive a State 
administered or monitored test, as specified in this paragraph (c)(3), 
prior to the performance of I/M-triggered repairs during the inspection 
cycle under consideration.
    (4) The program evaluation test data shall be submitted to EPA and 
shall be capable of providing accurate information about the overall 
effectiveness of an I/M program, such evaluation to begin no later than 
November 30, 1998.
    (5) Areas that qualify for and choose to implement an OTR low 
enhanced I/M program, as established in Sec. 51.351(h), and that claim 
in their SIP less emission reduction credit than the basic performance 
standard for one or more pollutants, are exempt from the requirements of 
paragraphs (c)(1) through (c)(4) of this section. The reports required 
under Sec. 51.366 of this part shall be sufficient in these areas to 
satisfy the requirements of Clean Air Act for program reporting.
    (d) SIP requirements. (1) The SIP shall include a description of the 
network to be employed, the required legal authority, and, in the case 
of areas making claims under paragraph (b) of this section, the required 
demonstration.
    (2) The SIP shall include a description of the evaluation schedule 
and protocol, the sampling methodology, the data collection and analysis 
system, the resources and personnel for evaluation, and related details 
of the evaluation program, and the legal authority enabling the 
evaluation program.

[57 FR 52987, Nov. 5, 1992, as amended at 58 FR 59367, Nov. 9, 1993; 61 
FR 39037, July 25, 1996; 63 FR 1368, Jan. 9, 1998]



Sec. 51.354  Adequate tools and resources.

    (a) Administrative resources. The program shall maintain the 
administrative resources necessary to perform all of the program 
functions including quality assurance, data analysis and reporting, and 
the holding of hearings and adjudication of cases. A portion of the test 
fee or a separately assessed per vehicle fee shall be collected, placed 
in a dedicated fund and retained, to be used to finance program 
oversight, management, and capital expenditures. Alternatives to this 
approach shall be acceptable if the State can demonstrate that adequate 
funding of the program can be maintained in some other fashion (e.g., 
through contractual obligation along with demonstrated past 
performance). Reliance on future uncommitted annual or biennial 
appropriations from the State or local General Fund is not acceptable, 
unless doing otherwise would be a violation of the State's constitution. 
This section shall in no way require the establishment of a test fee if 
the State chooses to fund the program in some other manner.
    (b) Personnel. The program shall employ sufficient personnel to 
effectively carry out the duties related to the program, including but 
not limited to administrative audits, inspector audits, data analysis, 
program oversight, program evaluation, public education and assistance, 
and enforcement against stations and inspectors as well as

[[Page 223]]

against motorists who are out of compliance with program regulations and 
requirements.
    (c) Equipment. The program shall possess equipment necessary to 
achieve the objectives of the program and meet program requirements, 
including but not limited to a steady supply of vehicles for covert 
auditing, test equipment and facilities for program evaluation, and 
computers capable of data processing, analysis, and reporting. Equipment 
or equivalent services may be contractor supplied or owned by the State 
or local authority.
    (d) SIP requirements. The SIP shall include a description of the 
resources that will be used for program operation, and discuss how the 
performance standard will be met.
    (1) The SIP shall include a detailed budget plan which describes the 
source of funds for personnel, program administration, program 
enforcement, purchase of necessary equipment (such as vehicles for 
undercover audits), and any other requirements discussed throughout, for 
the period prior to the next biennial self-evaluation required in 
Sec. 51.366 of this subpart.
    (2) The SIP shall include a description of personnel resources. The 
plan shall include the number of personnel dedicated to overt and covert 
auditing, data analysis, program administration, enforcement, and other 
necessary functions and the training attendant to each function.



Sec. 51.355  Test frequency and convenience.

    (a) The performance standards for I/M programs assume an annual test 
frequency; other schedules may be approved if the required emission 
targets are achieved. The SIP shall describe the test schedule in 
detail, including the test year selection scheme if testing is other 
than annual. The SIP shall include the legal authority necessary to 
implement and enforce the test frequency requirement and explain how the 
test frequency will be integrated with the enforcement process.
    (b) In enhanced I/M programs, test systems shall be designed in such 
a way as to provide convenient service to motorists required to get 
their vehicles tested. The SIP shall demonstrate that the network of 
stations providing test services is sufficient to insure short waiting 
times to get a test and short driving distances. Stations shall be 
required to adhere to regular testing hours and to test any subject 
vehicle presented for a test during its test period.



Sec. 51.356  Vehicle coverage.

    The performance standard for enhanced I/M programs assumes coverage 
of all 1968 and later model year light duty vehicles and light duty 
trucks up to 8,500 pounds GVWR, and includes vehicles operating on all 
fuel types. The standard for basic I/M programs does not include light 
duty trucks. Other levels of coverage may be approved if the necessary 
emission reductions are achieved. Vehicles registered or required to be 
registered within the I/M program area boundaries and fleets primarily 
operated within the I/M program area boundaries and belonging to the 
covered model years and vehicle classes comprise the subject vehicles.
    (a) Subject vehicles. (1) All vehicles of a covered model year and 
vehicle type shall be tested according to the applicable test schedule, 
including leased vehicles whose registration or titling is in the name 
of an equity owner other than the lessee or user.
    (2) All subject fleet vehicles shall be inspected. Fleets may be 
officially inspected outside of the normal I/M program test facilities, 
if such alternatives are approved by the program administration, but 
shall be subject to the same test requirements using the same quality 
control standards as non-fleet vehicles. If all vehicles in a particular 
fleet are tested during one part of the cycle, then the quality control 
requirements shall be met during the time of testing only. Any vehicle 
available for rent in the I/M area or for use in the I/M area shall be 
subject. Fleet vehicles not being tested in normal I/M test facilities 
in enhanced I/M programs, however, shall be inspected in independent, 
test-only facilities, according to the requirements of Sec. 51.353(a) of 
this subpart.
    (3) Subject vehicles which are registered in the program area but 
are primarily operated in another I/M area shall be tested, either in 
the area of

[[Page 224]]

primary operation, or in the area of registration. Alternate schedules 
may be established to permit convenient testing of these vehicles (e.g., 
vehicles belonging to students away at college should be rescheduled for 
testing during a visit home). I/M programs shall make provisions for 
providing official testing to vehicles registered elsewhere.
    (4) Vehicles which are operated on Federal installations located 
within an I/M program area shall be tested, regardless of whether the 
vehicles are registered in the State or local I/M area. This requirement 
applies to all employee-owned or leased vehicles (including vehicles 
owned, leased, or operated by civilian and military personnel on Federal 
installations) as well as agency-owned or operated vehicles, except 
tactical military vehicles, operated on the installation. This 
requirement shall not apply to visiting agency, employee, or military 
personnel vehicles as long as such visits do not exceed 60 calendar days 
per year. In areas without test fees collected in the lane, arrangements 
shall be made by the installation with the I/M program for reimbursement 
of the costs of tests provided for agency vehicles, at the discretion of 
the I/M agency. The installation shall provide documentation of proof of 
compliance to the I/M agency. The documentation shall include a list of 
subject vehicles and shall be updated periodically, as determined by the 
I/M program administrator, but no less frequently than each inspection 
cycle. The installation shall use one of the following methods to 
establish proof of compliance:
    (i) Presentation of a valid certificate of compliance from the local 
I/M program, from any other I/M program at least as stringent as the 
local program, or from any program deemed acceptable by the I/M program 
administrator.
    (ii) Presentation of proof of vehicle registration within the 
geographic area covered by the I/M program, except for any program whose 
enforcement is not through registration denial.
    (iii) Another method approved by the State or local I/M program 
administrator.
    (5) Special exemptions may be permitted for certain subject vehicles 
provided a demonstration is made that the performance standard will be 
met.
    (b) SIP requirements. (1) The SIP shall include a detailed 
description of the number and types of vehicles to be covered by the 
program, and a plan for how those vehicles are to be identified, 
including vehicles that are routinely operated in the area but may not 
be registered in the area.
    (2) The SIP shall include a description of any special exemptions 
which will be granted by the program, and an estimate of the percentage 
and number of subject vehicles which will be impacted. Such exemptions 
shall be accounted for in the emission reduction analysis.
    (3) The SIP shall include the legal authority or rule necessary to 
implement and enforce the vehicle coverage requirement.



Sec. 51.357  Test procedures and standards.

    Written test procedures and pass/fail standards shall be established 
and followed for each model year and vehicle type included in the 
program.
    (a) Test procedure requirements. Emission tests and functional tests 
shall be conducted according to good engineering practices to assure 
test accuracy.
    (1) Initial tests (i.e., those occurring for the first time in a 
test cycle) shall be performed without repair or adjustment at the 
inspection facility, prior to the test, except as provided in paragraph 
(a)(10)(i) of this section.
    (2) The vehicle owner or driver shall have access to the test area 
such that observation of the entire official inspection process on the 
vehicle is permitted. Such access may be limited but shall in no way 
prevent full observation.
    (3) An official test, once initiated, shall be performed in its 
entirety regardless of intermediate outcomes except in the case of 
invalid test condition, unsafe conditions, or fast pass/fail algorithms.
    (4) Tests involving measurement shall be performed with program-
approved equipment that has been calibrated accordingly to the quality 
procedures contained in appendix A to this subpart.

[[Page 225]]

    (5) Vehicles shall be rejected from testing if the exhaust system is 
missing or leaking, or if the vehicle is in an unsafe condition for 
testing.
    (6) Vehicles shall be retested after repair for any portion of the 
inspection that is failed on the previous test to determine if repairs 
were effective. To the extent that repair to correct a previous failure 
could lead to failure of another portion of the test, that portion shall 
also be retested. Evaporative system repairs shall trigger an exhaust 
emissions retest.
    (7) Steady-state testing. Steady-state tests shall be performed in 
accordance with the procedures contained in appendix B to this subpart.
    (8) Emission control device inspection. Visual emission control 
device checks shall be performed through direct observation or through 
indirect observation using a mirror, video camera or other visual aid. 
These inspections shall include a determination as to whether each 
subject device is present and appears to be properly connected and 
appears to be the correct type for the certified vehicle configuration.
    (9) Evaporative system purge test procedure. The purge test 
procedure shall consist of measuring the total purge flow (in standard 
liters) occurring in the vehicle's evaporative system during the 
transient dynamometer emission test specified in paragraph (a)(11) of 
this section. The purge flow measurement system shall be connected to 
the purge portion of the evaporative system in series between the 
canister and the engine, preferably near the canister. The inspector 
shall be responsible for ensuring that all items that are disconnected 
in the conduct of the test procedure are properly re-connected at the 
conclusion of the test procedure. Alternative procedures may be used if 
they are shown to be equivalent or better to the satisfaction of the 
Administrator. Except in the case of government-run test facilities 
claiming sovereign immunity, any damage done to the evaporative emission 
control system during this test shall be repaired at the expense of the 
inspection facility.
    (10) Evaporative system integrity test procedure. The test sequence 
shall consist of the following steps:
    (i) Test equipment shall be connected to the fuel tank canister hose 
at the canister end. The gas cap shall be checked to ensure that it is 
properly, but not excessively tightened, and shall be tightened if 
necessary.
    (ii) The system shall be pressurized to 140.5 inches of 
water without exceeding 26 inches of water system pressure.
    (iii) Close off the pressure source, seal the evaporative system and 
monitor pressure decay for up to two minutes.
    (iv) Loosen the gas cap after a maximum of two minutes and monitor 
for a sudden pressure drop, indicating that the fuel tank was 
pressurized.
    (v) The inspector shall be responsible for ensuring that all items 
that are disconnected in the conduct of the test procedure are properly 
re-connected at the conclusion of the test procedure.
    (vi) Alternative procedures may be used if they are shown to be 
equivalent or better to the satisfaction of the Administrator. Except in 
the case of government-run test facilities claiming sovereign immunity, 
any damage done to the evaporative emission control system during this 
test shall be repaired at the expense of the inspection facility.
    (11) Transient emission test. The transient emission test shall 
consist of 240 seconds of mass emission measurement using a constant 
volume sampler while the vehicle is driven through a computer-monitored 
driving cycle on a dynamometer with inertial weight settings appropriate 
for the weight of the vehicle. The driving cycle shall include 
acceleration, deceleration, and idle operating modes as specified in 
appendix E to this subpart. The 240 second sequence may be ended earlier 
using fast pass or fast fail algorithms and multiple pass/fail 
algorithms may be used during the test cycle to eliminate false 
failures. The transient test procedure, including algorithms and other 
procedural details, shall be approved by the Administrator prior to use 
in an I/M program.
    (12) On-board diagnostic checks. Inspection of the on-board 
diagnostic system shall be according to the procedure described in 40 
CFR 85.2222, at a minimum.

[[Page 226]]

    (13) Approval of alternative tests. Alternative test procedures may 
be approved if the Administrator finds that--
    (i) Such procedures are in accordance with good engineering 
practice, including errors of commission (at cutpoints corresponding to 
equivalent emission reductions) no higher than the tests they would 
replace;
    (ii) Such procedures show a correlation with the Federal Test 
Procedure (with respect to their ability to detect high emitting 
vehicles and ensure their effective repair) equal to or better than the 
tests they would replace; and
    (iii) Such procedures would produce equivalent emission reductions 
in combination with other program elements.
    (b) Test standards--(1) Emissions standards. HC, CO, and 
CO+CO2 (or CO2 alone) emission standards shall be 
applicable to all vehicles subject to the program and repairs shall be 
required for failure of any standard regardless of the attainment status 
of the area. NOX emission standards shall be applied to 
vehicles subject to a transient test in ozone nonattainment areas and in 
an ozone transport region, unless a waiver of NOX controls is 
provided to the State under Sec. 51.351(d) of this subpart.
    (i) Steady-state short tests. The steady-state short test emission 
standards for 1981 and later model year light duty vehicles and light 
duty trucks shall be at least as stringent as those in appendix C to 
this subpart.
    (ii) Transient test. Transient test emission standards shall be 
established for HC, CO, CO2, and NOX for subject 
vehicles based on model year and vehicle type.
    (2) Visual equipment inspection standards. (i) Vehicles shall fail 
visual inspections of subject emission control devices if such devices 
are part of the original certified configuration and are found to be 
missing, modified, disconnected, or improperly connected.
    (ii) Vehicles shall fail visual inspections of subject emission 
control devices if such devices are found to be incorrect for the 
certified vehicle configuration under inspection. Aftermarket parts, as 
well as original equipment manufacture parts, may be considered correct 
if they are proper for the certified vehicle configuration. Where an EPA 
aftermarket approval or self-certification program exists for a 
particular class of subject parts, vehicles shall fail visual equipment 
inspections if the part is neither original equipment manufacture nor 
from an approved or self-certified aftermarket manufacturer.
    (3) Functional test standards--(i) Evaporative system integrity 
test. Vehicles shall fail the evaporative system pressure test if the 
system cannot maintain a system pressure above eight inches of water for 
up to two minutes after being pressurized to 140.5 inches of 
water or if no pressure drop is detected when the gas cap is loosened as 
described in paragraph (a)(10)(iv) of this section. Additionally, 
vehicles shall fail the evaporative test if the canister is missing or 
obviously damaged, if hoses are missing or obviously disconnected, or if 
the gas cap is missing.
    (ii) Evaporative canister purge test. Vehicles with a total purge 
system flow measuring less than one liter, over the course of the 
transient test required in paragraph (a)(9) of this section, shall fail 
the evaporative purge test.
    (4) On-board diagnostics test standards. Vehicles shall fail the on-
board diagnostic test if they fail to meet the requirements of 40 CFR 
85.2207, at a minimum. Failure of the on-board diagnostic test need not 
result in failure of the vehicle inspection/maintenance test until 
January 1, 2001.
    (c) Fast test algorithms and standards. Special test algorithms and 
pass/fail algorithms may be employed to reduce test time when the test 
outcome is predictable with near certainty, if the Administrator 
approves by letter the equivalency to full procedure testing.
    (d) Applicability. In general, section 203(a)(3)(A) of the Clean Air 
Act prohibits altering a vehicle's configuration such that it changes 
from a certified to a non-certified configuration. In the inspection 
process, vehicles that have been altered from their original certified 
configuration are to be tested in the same manner as other subject 
vehicles.
    (1) Vehicles with engines other than the engine originally installed 
by the manufacturer or an identical replacement of such engine shall be 
subject to

[[Page 227]]

the test procedures and standards for the chassis type and model year 
including visual equipment inspections for all parts that are part of 
the original or now-applicable certified configuration and part of the 
normal inspection. States may choose to require vehicles with such 
engines to be subject to the test procedures and standards for the 
engine model year if it is newer than the chassis model year.
    (2) Vehicles that have been switched from an engine of one fuel type 
to another fuel type that is subject to the program (e.g., from a diesel 
engine to a gasoline engine) shall be subject to the test procedures and 
standards for the current fuel type, and to the requirements of 
paragraph (d)(1) of this section.
    (3) Vehicles that are switched to a fuel type for which there is no 
certified configuration shall be tested according to the most stringent 
emission standards established for that vehicle type and model year. 
Emission control device requirements may be waived if the program 
determines that the alternatively fueled vehicle configuration would 
meet the new vehicle standards for that model year without such devices.
    (4) Mixing vehicle classes (e.g., light-duty with heavy-duty) and 
certification types (e.g., California with Federal) within a single 
vehicle configuration shall be considered tampering.
    (e) SIP requirements. The SIP shall include a description of each 
test procedure used. The SIP shall include the rule, ordinance or law 
describing and establishing the test procedures.

[57 FR 52987, Nov. 5, 1992, as amended at 61 FR 40945, Aug. 6, 1996; 63 
FR 24433, May 4, 1998]



Sec. 51.358  Test equipment.

    Computerized test systems are required for performing any 
measurement on subject vehicles.
    (a) Performance features of computerized test systems. The test 
equipment shall be certified by the program to meet the requirements 
contained in appendix D to this subpart, and newly acquired systems 
shall be subjected to acceptance test procedures to ensure compliance 
with program specifications.
    (1) Emission test equipment shall be capable of testing all subject 
vehicles and shall be updated from time to time to accommodate new 
technology vehicles as well as changes to the program.
    (2) At a minimum, emission test equipment:
    (i) Shall be automated to the highest degree commercially available 
to minimize the potential for intentional fraud and/or human error;
    (ii) Shall be secure from tampering and/or abuse;
    (iii) Shall be based upon written specifications; and
    (iv) Shall be capable of simultaneously sampling dual exhaust 
vehicles.
    (3) The vehicle owner or driver shall be provided with a computer-
generated record of test results, including all of the items listed in 
40 CFR part 85, subpart W as being required on the test record. The test 
report shall include:
    (i) A vehicle description, including license plate number, vehicle 
identification number, and odometer reading;
    (ii) The date and time of test;
    (iii) The name or identification number of the individual(s) 
performing the tests and the location of the test station and lane;
    (iv) The type of tests performed, including emission tests, visual 
checks for the presence of emission control components, and functional, 
evaporative system checks;
    (v) The applicable test standards;
    (vi) The test results, including exhaust concentrations and pass/
fail results for each mode measured, pass/fail results for evaporative 
system checks, and which emission control devices inspected were passed, 
failed, or not applicable;
    (vii) A statement indicating the availability of warranty coverage 
as required in section 207 of the Clean Air Act;
    (viii) Certification that tests were performed in accordance with 
the regulations and, in the case of decentralized programs, the 
signature of the individual who performed the test; and
    (ix) For vehicles that fail the tailpipe emission test, information 
on the possible causes of the specific pattern of high emission levels 
found during the test.

[[Page 228]]

    (b) Functional characteristics of computerized test systems. The 
test system is composed of emission measurement devices and other motor 
vehicle test equipment controlled by a computer.
    (1) The test system shall automatically:
    (i) Make a pass/fail decision for all measurements;
    (ii) Record test data to an electronic medium;
    (iii) Conduct regular self-testing of recording accuracy;
    (iv) Perform electrical calibration and system integrity checks 
before each test, as applicable; and
    (v) Initiate system lockouts for:
    (A) Tampering with security aspects of the test system;
    (B) Failing to conduct or pass periodic calibration or leak checks;
    (C) Failing to conduct or pass the constant volume sampler flow rate 
check (if applicable);
    (D) Failing to conduct or pass any of the dynamometer checks, 
including coast-down, roll speed and roll distance, power absorption 
capability, and inertia weight selection checks (if applicable);
    (E) Failing to conduct or pass the pressure monitoring device check 
(if applicable);
    (F) Failing to conduct or pass the purge flow metering system check 
(if applicable); and
    (G) A full data recording medium or one that does not pass a 
cyclical redundancy check.
    (2) Test systems in enhanced I/M programs shall include a real-time 
data link to a host computer that prevents unauthorized multiple initial 
tests on the same vehicle in a test cycle and to insure test record 
accuracy.
    (3) The test system shall insure accurate data collection by 
limiting, cross-checking, and/or confirming manual data entry.
    (4) On-board diagnostic test equipment requirements. The test 
equipment used to perform on-board diagnostic inspections shall function 
as specified in 40 CFR 85.2231.
    (c) SIP requirements. The SIP shall include written technical 
specifications for all test equipment used in the program and shall 
address each of the above requirements. The specifications shall 
describe the emission analysis process, the necessary test equipment, 
the required features, and written acceptance testing criteria and 
procedures.

[57 FR 52987, Nov. 5, 1992, as amended at 61 FR 40945, Aug. 6, 1996]



Sec. 51.359  Quality control.

    Quality control measures shall insure that emission measurement 
equipment is calibrated and maintained properly, and that inspection, 
calibration records, and control charts are accurately created, recorded 
and maintained.
    (a) General requirements. (1) The practices described in this 
section and in appendix A to this subpart shall be followed, at a 
minimum. Alternatives or exceptions to these procedures or frequencies 
may be approved by the Administrator based on a demonstration, including 
control chart analysis, of equivalent performance.
    (2) Preventive maintenance on all inspection equipment necessary to 
insure accurate and repeatable operation shall be performed on a 
periodic basis.
    (3) Computerized analyzers shall automatically record quality 
control check information, lockouts, attempted tampering, and any other 
recordable circumstances which should be monitored to insure quality 
control (e.g., service calls).
    (b) Requirements for steady-state emissions testing equipment. (1) 
Equipment shall be maintained according to demonstrated good engineering 
practices to assure test accuracy. The calibration and adjustment 
requirements in appendix A to this subpart shall apply to all steady-
state test equipment. States may adjust calibration schedules and other 
quality control frequencies by using statistical process control to 
monitor equipment performance on an ongoing basis.
    (2) For analyzers that use ambient air as zero air, provision shall 
be made to draw the air from outside the inspection bay or lane in which 
the analyzer is situated.
    (3) The analyzer housing shall be constructed to protect the 
analyzer bench

[[Page 229]]

and electrical components from ambient temperature and humidity 
fluctuations that exceed the range of the analyzer's design 
specifications.
    (4) Analyzers shall automatically purge the analytical system after 
each test.
    (c) Requirements for transient exhaust emission test equipment. 
Equipment shall be maintained according to demonstrated good engineering 
practices to assure test accuracy. Computer control of quality assurance 
checks and quality control charts shall be used whenever possible. 
Exceptions to the procedures and the frequency of the checks described 
in appendix A of this subpart may be approved by the Administrator based 
on a demonstration of equivalent performance.
    (d) Requirements for evaporative system functional test equipment. 
Equipment shall be maintained according to demonstrated good engineering 
practices to assure test accuracy. Computer control of quality assurance 
checks and quality control charts shall be used whenever possible. 
Exceptions to the procedures and the frequency of the checks described 
in appendix A of this subpart may be approved by the Administrator based 
on a demonstration of equivalent performance.
    (e) Document security. Measures shall be taken to maintain the 
security of all documents by which compliance with the inspection 
requirement is established including, but not limited to inspection 
certificates, waiver certificates, license plates, license tabs, and 
stickers. This section shall in no way require the use of paper 
documents but shall apply if they are used by the program for these 
purposes.
    (1) Compliance documents shall be counterfeit resistant. Such 
measures as the use of special fonts, water marks, ultra-violet inks, 
encoded magnetic strips, unique bar-coded identifiers, and difficult to 
acquire materials may be used to accomplish this requirement.
    (2) All inspection certificates, waiver certificates, and stickers 
shall be printed with a unique serial number and an official program 
seal.
    (3) Measures shall be taken to ensure that compliance documents 
cannot be stolen or removed without being damaged.
    (f) SIP requirements. The SIP shall include a description of quality 
control and record keeping procedures. The SIP shall include the 
procedure manual, rule, ordinance or law describing and establishing the 
quality control procedures and requirements.

[57 FR 52987, Nov. 5, 1992, as amended at 58 FR 59367, Nov. 9, 1993]



Sec. 51.360  Waivers and compliance via diagnostic inspection.

    The program may allow the issuance of a waiver, which is a form of 
compliance with the program requirements that allows a motorist to 
comply without meeting the applicable test standards, as long as the 
prescribed criteria described below are met.
    (a) Waiver issuance criteria. The waiver criteria shall include the 
following at a minimum.
    (1) Waivers shall be issued only after a vehicle has failed a retest 
performed after all qualifying repairs have been completed. Qualifying 
repairs include repairs of the emission control components, listed in 
paragraph (a)(5) of this section, performed within 60 days of the test 
date.
    (2) Any available warranty coverage shall be used to obtain needed 
repairs before expenditures can be counted towards the cost limits in 
paragraphs (a)(5) and (a)(6) of this section. The operator of a vehicle 
within the statutory age and mileage coverage under section 207(b) of 
the Clean Air Act shall present a written denial of warranty coverage 
from the manufacturer or authorized dealer for this provision to be 
waived for approved tests applicable to the vehicle.
    (3) Waivers shall not be issued to vehicles for tampering-related 
repairs. The cost of tampering-related repairs shall not be applicable 
to the minimum expenditure in paragraphs (a)(5) and (a)(6) of this 
section. States may issue exemptions for tampering-related repairs if it 
can be verified that the part in question or one similar to it is no 
longer available for sale.
    (4) Repairs shall be appropriate to the cause of the test failure, 
and a visual check shall be made to determine if repairs were actually 
made if, given

[[Page 230]]

the nature of the repair, it can be visually confirmed. Receipts shall 
be submitted for review to further verify that qualifying repairs were 
performed.
    (5) General repairs shall be performed by a recognized repair 
technician (i.e., one professionally engaged in vehicle repair, employed 
by a going concern whose purpose is vehicle repair, or possessing 
nationally recognized certification for emission-related diagnosis and 
repair) in order to qualify for a waiver. I/M programs may allow the 
cost of parts (not labor) utilized by non-technicians (e.g., owners) to 
apply toward the waiver limit. The waiver would apply to the cost of 
parts for the repair or replacement of the following list of emission 
control components: oxygen sensor, catalytic converter, thermal reactor, 
EGR valve, fuel filler cap, evaporative canister, PCV valve, air pump, 
distributor, ignition wires, coil, and spark plugs. The cost of any 
hoses, gaskets, belts, clamps, brackets or other accessories directly 
associated with these components may also be applied to the waiver 
limit.
    (6) In basic programs, a minimum of $75 for pre-81 vehicles and $200 
for 1981 and newer vehicles shall be spent in order to qualify for a 
waiver. These model year cutoffs and the associated dollar limits shall 
be in full effect no later than January 1, 1998. Prior to January 1, 
1998, States may adopt any minimum expenditure commensurate with the 
waiver rate committed to for the purposes of modeling compliance with 
the basic I/M performance standard.
    (7) Beginning on January 1, 1998, enhanced I/M programs shall 
require the motorist to make an expenditure of at least $450 in repairs 
to qualify for a waiver. The I/M program shall provide that the $450 
minimum expenditure shall be adjusted in January of each year by the 
percentage, if any, by which the Consumer Price Index for the preceding 
calendar year differs from the Consumer Price Index of 1989. Prior to 
January 1, 1998, States may adopt any minimum expenditure commensurate 
with the waiver rate committed to for the purposes of modeling 
compliance with the relevant enhanced I/M performance standard.
    (i) The Consumer Price Index for any calendar year is the average of 
the Consumer Price Index for all-urban consumers published by the 
Department of Labor, as of the close of the 12-month period ending on 
August 31 of each calendar year. A copy of the current Consumer Price 
Index may be obtained from the Emission Planning and Strategies 
Division, U.S. Environmental Protection Agency, 2565 Plymouth Road, Ann 
Arbor, Michigan 48105.
    (ii) The revision of the Consumer Price Index which is most 
consistent with the Consumer Price Index for calendar year 1989 shall be 
used.
    (8) States may establish lower minimum expenditures if a program is 
established to scrap vehicles that do not meet standards after the lower 
expe nditure is made.
    (9) A time extension, not to exceed the period of the inspection 
frequency, may be granted to obtain needed repairs on a vehicle in the 
case of economic hardship when waiver requirements have not been met. 
After having received a time extension, a vehicle must fully pass the 
applicable test standards before becoming eligible for another time 
extension. The extension for a vehicle shall be tracked and reported by 
the program.
    (b) Compliance via diagnostic inspection. Vehicles subject to a 
transient IM240 emission test at the cutpoints established in 
Secs. 51.351 (f)(7) and (g)(7) of this subpart may be issued a 
certificate of compliance without meeting the prescribed emission 
cutpoints, if, after failing a retest on emissions, a complete, 
documented physical and functional diagnosis and inspection performed by 
the I/M agency or a contractor to the I/M agency show that no additional 
emission-related repairs are needed. Any such exemption policy and 
procedures shall be subject to approval by the Administrator.
    (c) Quality control of waiver issuance. (1) Enhanced programs shall 
control waiver issuance and processing by establishing a system of 
agency-issued waivers. The State may delegate this authority to a single 
contractor but inspectors in stations and lanes shall not issue waivers. 
Basic programs may permit inspector-issued waivers as long as quality 
assurance efforts include a

[[Page 231]]

comprehensive review of waiver issuance.
    (2) The program shall include methods of informing vehicle owners or 
lessors of potential warranty coverage, and ways to obtain warranty 
repairs.
    (3) The program shall insure that repair receipts are authentic and 
cannot be revised or reused.
    (4) The program shall insure that waivers are only valid for one 
test cycle.
    (5) The program shall track, manage, and account for time extensions 
or exemptions so that owners or lessors cannot receive or retain a 
waiver improperly.
    (d) SIP requirements. (1) The SIP shall include a maximum waiver 
rate expressed as a percentage of initially failed vehicles. This waiver 
rate shall be used for estimating emission reduction benefits in the 
modeling analysis.
    (2) The State shall take corrective action if the waiver rate 
exceeds that committed to in the SIP or revise the SIP and the emission 
reductions claimed.
    (3) The SIP shall describe the waiver criteria and procedures, 
including cost limits, quality assurance methods and measures, and 
administration.
    (4) The SIP shall include the necessary legal authority, ordinance, 
or rules to issue waivers, set and adjust cost limits as required in 
paragraph (a)(5) of this section, and carry out any other functions 
necessary to administer the waiver system, including enforcement of the 
waiver provisions.

[57 FR 52987, Nov. 5, 1992, as amended at 58 FR 59367, Nov. 9, 1993; 60 
FR 48036, Sept. 18, 1995]



Sec. 51.361  Motorist compliance enforcement.

    Compliance shall be ensured through the denial of motor vehicle 
registration in enhanced I/M programs unless an exception for use of an 
existing alternative is approved. An enhanced I/M area may use an 
existing alternative if it demonstrates that the alternative has been 
more effective than registration denial. An enforcement mechanism may be 
considered an ``existing alternative'' only in States that, for some 
area in the State, had an I/M program with that mechanism in operation 
prior to passage of the 1990 Amendments to the Act. A basic I/M area may 
use an alternative enforcement mechanism if it demonstrates that the 
alternative will be as effective as registration denial. Two other types 
of enforcement programs may qualify for enhanced I/M programs if 
demonstrated to have been more effective than enforcement of the 
registration requirement in the past: Sticker-based enforcement programs 
and computer-matching programs. States that did not adopt an I/M program 
for any area of the State before November 15, 1990, may not use an 
enforcement alternative in connection with an enhanced I/M program 
required to be adopted after that date.
    (a) Registration denial. Registration denial enforcement is defined 
as rejecting an application for initial registration or reregistration 
of a used vehicle (i.e., a vehicle being registered after the initial 
retail sale and associated registration) unless the vehicle has complied 
with the I/M requirement prior to granting the application. Pursuant to 
section 207(g)(3) of the Act, nothing in this subpart shall be construed 
to require that new vehicles shall receive emission testing prior to 
initial retail sale. In designing its enforcement program, the State 
shall:
    (1) Provide an external, readily visible means of determining 
vehicle compliance with the registration requirement to facilitate 
enforcement of the program;
    (2) Adopt a schedule of testing (either annual or biennial) that 
clearly determines when a vehicle shall comply prior to registration;
    (3) Design a testing certification mechanism (either paper-based or 
electronic) that shall be used for registration purposes and clearly 
indicates whether the certification is valid for purposes of 
registration, including:
    (i) Expiration date of the certificate;
    (ii) Unambiguous vehicle identification information; and
    (iii) Whether the vehicle passed or received a waiver;
    (4) Routinely issue citations to motorists with expired or missing 
license plates, with either no registration or an expired registration, 
and with no license plate decals or expired decals,

[[Page 232]]

and provide for enforcement officials other than police to issue 
citations (e.g., parking meter attendants) to parked vehicles in 
noncompliance;
    (5) Structure the penalty system to deter non-compliance with the 
registration requirement through the use of mandatory minimum fines 
(meaning civil, monetary penalties, in this subpart) constituting a 
meaningful deterrent and through a requirement that compliance be 
demonstrated before a case can be closed;
    (6) Ensure that evidence of testing is available and checked for 
validity at the time of a new registration of a used vehicle or 
registration renewal;
    (7) Prevent owners or lessors from avoiding testing through 
manipulation of the title or registration system; title transfers may 
re-start the clock on the inspection cycle only if proof of current 
compliance is required at title transfer;
    (8) Prevent the fraudulent initial classification or 
reclassification of a vehicle from subject to non-subject or exempt by 
requiring proof of address changes prior to registration record 
modification, and documentation from the testing program (or delegate) 
certifying based on a physical inspection that the vehicle is exempt;
    (9) Limit and track the use of time extensions of the registration 
requirement to prevent repeated extensions;
    (10) Provide for meaningful penalties for cases of registration 
fraud;
    (11) Limit and track exemptions to prevent abuse of the exemption 
policy for vehicles claimed to be out-of-state; and
    (12) Encourage enforcement of vehicle registration transfer 
requirements when vehicle owners move into the I/M area by coordinating 
with local and State enforcement agencies and structuring other 
activities (e.g., drivers license issuance) to effect registration 
transfers.
    (b) Alternative enforcement mechanisms--(1) General requirements. 
The program shall demonstrate that a non-registration-based enforcement 
program is currently more effective than registration-denial enforcement 
in enhanced I/M programs or, prospectively, as effective as registration 
denial in basic programs. The following general requirements shall 
apply:
    (i) For enhanced I/M programs, the area in question shall have had 
an operating I/M program using the alternative mechanism prior to 
enactment of the Clean Air Act Amendments of 1990. While modifications 
to improve compliance may be made to the program that was in effect at 
the time of enactment, the expected change in effectiveness cannot be 
considered in determining acceptability;
    (ii) The State shall assess the alternative program's effectiveness, 
as well as the current effectiveness of the registration system, 
including the following:
    (A) Determine the number and percentage of vehicles subject to the 
I/M program that were in compliance with the program over the course of 
at least one test cycle; and
    (B) Determine the number and fraction of the same group of vehicles 
as in paragraph (b)(1)(ii)(A) of this section that were in compliance 
with the registration requirement over the same period. Late 
registration shall not be considered non-compliance for the purposes of 
this determination. The precise definition of late registration versus a 
non-complying vehicle shall be explained and justified in the SIP;
    (iii) An alternative mechanism shall be considered more effective if 
the fraction of vehicles complying with the existing program, as 
determined according to the requirements of this section, is greater 
than the fraction of vehicles complying with the registration 
requirement. An alternative mechanism is as effective if the fraction 
complying with the program is at least equal to the fraction complying 
with the registration requirement.
    (2) Sticker-based enforcement. In addition to the general 
requirements, a sticker-based enforcement program shall demonstrate that 
the enforcement mechanism will swiftly and effectively prevent operation 
of subject vehicles that fail to comply. Such demonstration shall 
include the following:
    (i) An assessment of the current extent of the following forms of 
non-compliance and demonstration that mechanisms exist to keep such non-
compliance within acceptable limits:

[[Page 233]]

    (A) Use of stolen, counterfeit, or fraudulently obtained stickers;
    (B) In States with safety inspections, the use of ``Safety 
Inspection Only'' stickers on vehicles that should be subject to the I/M 
requirement as well; and
    (C) Operation of vehicles with expired stickers, including a 
stratification of non-compliance by length of noncompliance and model 
year.
    (ii) The program as currently implemented or as proposed to be 
improved shall also:
    (A) Require an easily observed external identifier such as the 
county name on the license plate, an obviously unique license plate tab, 
or other means that shows whether or not a vehicle is subject to the I/M 
requirement;
    (B) Require an easily observed external identifier, such as a 
windshield sticker or license plate tab that shows whether a subject 
vehicle is in compliance with the inspection requirement;
    (C) Impose monetary fines at least as great as the estimated cost of 
compliance with I/M requirements (e.g., test fee plus minimum waiver 
expenditure) for the absence of such identifiers;
    (D) Require that such identifiers be of a quality that makes them 
difficult to counterfeit, difficult to remove without destroying once 
installed, and durable enough to last until the next inspection without 
fading, peeling, or other deterioration;
    (E) Perform surveys in a variety of locations and at different times 
for the presence of the required identifiers such that at least 10% of 
the vehicles or 10,000 vehicles (whichever is less) in the subject 
vehicle population are sampled each year;
    (F) Track missing identifiers for all inspections performed at each 
station, with stations being held accountable for all such identifiers 
they are issued; and
    (G) Assess and collect significant fines for each identifier that is 
unaccounted for by a station.
    (3) Computer matching. In addition to the general requirements, 
computer-matching programs shall demonstrate that the enforcement 
mechanism will swiftly and effectively prevent operation of subject 
vehicles that fail to comply. Such demonstration shall:
    (i) Require an expeditious system that results in at least 90% of 
the subject vehicles in compliance within 4 months of the compliance 
deadline;
    (ii) Require that subject vehicles be given compliance deadlines 
based on the regularly scheduled test date, not the date of previous 
compliance;
    (iii) Require that motorists pay monetary fines at least as great as 
the estimated cost of compliance with I/M requirements (e.g., test fee 
plus minimum waiver expenditure) for the continued operation of a 
noncomplying vehicle beyond 4 months of the deadline;
    (iv) Require that continued non-compliance will eventually result in 
preventing operation of the non-complying vehicle (no later than the 
date of the next test cycle) through, at a minimum, suspension of 
vehicle registration and subsequent denial of reregistration;
    (v) Demonstrate that the computer system currently in use is 
adequate to store and manipulate the I/M vehicle database, generate 
computerized notices, and provide regular backup to said system while 
maintaining auxiliary storage devices to insure ongoing operation of the 
system and prevent data losses;
    (vi) Track each vehicle through the steps taken to ensure 
compliance, including:
    (A) The compliance deadline;
    (B) The date of initial notification;
    (C) The dates warning letters are sent to non-complying vehicle 
owners;
    (D) The dates notices of violation or other penalty notices are 
sent; and
    (E) The dates and outcomes of other steps in the process, including 
the final compliance date;
    (vii) Compile and report monthly summaries including statistics on 
the percentage of vehicles at each stage in the enforcement process; and
    (viii) Track the number and percentage of vehicles initially 
identified as requiring testing but which are never tested as a result 
of being junked, sold to a motorist in a non-I/M program area, or for 
some other reason.
    (c) SIP requirements. (1) The SIP shall provide information 
concerning the enforcement process, including:
    (i) A description of the existing compliance mechanism if it is to 
be used in

[[Page 234]]

the future and the demonstration that it is as effective or more 
effective than registration-denial enforcement;
    (ii) An identification of the agencies responsible for performing 
each of the applicable activities in this section;
    (iii) A description of and accounting for all classes of exempt 
vehicles; and
    (iv) A description of the plan for testing fleet vehicles, rental 
car fleets, leased vehicles, and any other subject vehicles, e.g., those 
operated in (but not necessarily registered in) the program area.
    (2) The SIP shall include a determination of the current compliance 
rate based on a study of the system that includes an estimate of 
compliance losses due to loopholes, counterfeiting, and unregistered 
vehicles. Estimates of the effect of closing such loopholes and 
otherwise improving the enforcement mechanism shall be supported with 
detailed analyses.
    (3) The SIP shall include the legal authority to implement and 
enforce the program.
    (4) The SIP shall include a commitment to an enforcement level to be 
used for modeling purposes and to be maintained, at a minimum, in 
practice.

[57 FR 52987, Nov. 5, 1992, as amended at 61 FR 49682, Sept. 23, 1996]



Sec. 51.362  Motorist compliance enforcement program oversight.

    The enforcement program shall be audited regularly and shall follow 
effective program management practices, including adjustments to improve 
operation when necessary.
    (a) Quality assurance and quality control. A quality assurance 
program shall be implemented to insure effective overall performance of 
the enforcement system. Quality control procedures are required to 
instruct individuals in the enforcement process regarding how to 
properly conduct their activities. At a minimum, the quality control and 
quality assurance program shall include:
    (1) Verification of exempt vehicle status by inspecting and 
confirming such vehicles by the program or its delegate;
    (2) Facilitation of accurate critical test data and vehicle 
identifier collection through the use of automatic data capture systems 
such as bar-code scanners or optical character readers, or through 
redundant data entry;
    (3) Maintenance of an audit trail to allow for the assessment of 
enforcement effectiveness;
    (4) Establishment of written procedures for personnel directly 
engaged in I/M enforcement activities;
    (5) Establishment of written procedures for personnel engaged in I/M 
document handling and processing, such as registration clerks or 
personnel involved in sticker dispensing and waiver processing, as well 
as written procedures for the auditing of their performance;
    (6) Follow-up validity checks on out-of-area or exemption-triggering 
registration changes;
    (7) Analysis of registration-change applications to target potential 
violators;
    (8) A determination of enforcement program effectiveness through 
periodic audits of test records and program compliance documentation;
    (9) Enforcement procedures for disciplining, retraining, or removing 
enforcement personnel who deviate from established requirements, or in 
the case of non-government entities that process registrations, for 
defranchising, revoking or otherwise discontinuing the activity of the 
entity issuing registrations; and
    (10) The prevention of fraudulent procurement or use of inspection 
documents by controlling and tracking document distribution and 
handling, and making stations financially liable for missing or 
unaccounted for documents by assessing monetary fines reflecting the 
``street value'' of these documents (i.e., the test fee plus the minimum 
waiver expenditure).
    (b) Information management. In establishing an information base to 
be used in characterizing, evaluating, and enforcing the program, the 
State shall:
    (1) Determine the subject vehicle population;
    (2) Permit EPA audits of the enforcement process;
    (3) Assure the accuracy of registration and other program document 
files;
    (4) Maintain and ensure the accuracy of the testing database through 
periodic internal and/or third-party review;

[[Page 235]]

through automated or redundant data entry; and, through automated 
analysis for valid alpha-numeric sequences of the vehicle identification 
number (VIN), certificate number, or license plate number;
    (5) Compare the testing database to the registration database to 
determine program effectiveness, establish compliance rates, and to 
trigger potential enforcement action against non-complying motorists; 
and
    (6) Sample the fleet as a determination of compliance through 
parking lot surveys, road-side pull-overs, or other in-use vehicle 
measurements.
    (c) SIP requirements. The SIP shall include a description of 
enforcement program oversight and information management activities.



Sec. 51.363  Quality assurance.

    An ongoing quality assurance program shall be implemented to 
discover, correct and prevent fraud, waste, and abuse and to determine 
whether procedures are being followed, are adequate, whether equipment 
is measuring accurately, and whether other problems might exist which 
would impede program performance. The quality assurance and quality 
control procedures shall be periodically evaluated to assess their 
effectiveness and relevance in achieving program goals.
    (a) Performance audits. Performance audits shall be conducted on a 
regular basis to determine whether inspectors are correctly performing 
all tests and other required functions. Performance audits shall be of 
two types: overt and covert, and shall include:
    (1) Performance audits based upon written procedures and results 
shall be reported using either electronic or written forms to be 
retained in the inspector and station history files, with sufficient 
detail to support either an administrative or civil hearing;
    (2) Performance audits in addition to regularly programmed audits 
for stations employing inspectors suspected of violating regulations as 
a result of audits, data analysis, or consumer complaints;
    (3) Overt performance audits shall be performed at least twice per 
year for each lane or test bay and shall include:
    (i) A check for the observance of appropriate document security;
    (ii) A check to see that required record keeping practices are being 
followed;
    (iii) A check for licenses or certificates and other required 
display information; and
    (iv) Observation and written evaluation of each inspector's ability 
to properly perform an inspection;
    (4) Covert performance audits shall include:
    (i) Remote visual observation of inspector performance, which may 
include the use of aids such as binoculars or video cameras, at least 
once per year per inspector in high-volume stations (i.e., those 
performing more than 4000 tests per year);
    (ii) Site visits at least once per year per number of inspectors 
using covert vehicles set to fail (this requirement sets a minimum level 
of activity, not a requirement that each inspector be involved in a 
covert audit);
    (iii) For stations that conduct both testing and repairs, at least 
one covert vehicle visit per station per year including the purchase of 
repairs and subsequent retesting if the vehicle is initially failed for 
tailpipe emissions (this activity may be accomplished in conjunction 
with paragraph (a)(4)(ii) of this section but must involve each station 
at least once per year);
    (iv) Documentation of the audit, including vehicle condition and 
preparation, sufficient for building a legal case and establishing a 
performance record;
    (v) Covert vehicles covering the range of vehicle technology groups 
(e.g., carbureted and fuel-injected vehicles) included in the program, 
including a full range of introduced malfunctions covering the emission 
test, the evaporative system tests, and emission control component 
checks (as applicable);
    (vi) Sufficient numbers of covert vehicles and auditors to allow for 
frequent rotation of both to prevent detection by station personnel; and
    (vii) Access to on-line inspection databases by State personnel to 
permit the creation and maintenance of covert vehicle records.
    (b) Record audits. Station and inspector records shall be reviewed 
or

[[Page 236]]

screened at least monthly to assess station performance and identify 
problems that may indicate potential fraud or incompetence. Such review 
shall include:
    (1) Software-based, computerized analysis to identify statistical 
inconsistencies, unusual patterns, and other discrepancies;
    (2) Visits to inspection stations to review records not already 
covered in the electronic analysis (if any); and
    (3) Comprehensive accounting for all official forms that can be used 
to demonstrate compliance with the program.
    (c) Equipment audits. During overt site visits, auditors shall 
conduct quality control evaluations of the required test equipment, 
including (where applicable):
    (1) A gas audit using gases of known concentrations at least as 
accurate as those required for regular equipment quality control and 
comparing these concentrations to actual readings;
    (2) A check for tampering, worn instrumentation, blocked filters, 
and other conditions that would impede accurate sampling;
    (3) A check for critical flow in critical flow CVS units;
    (4) A check of the Constant Volume Sampler flow calibration;
    (5) A check for the optimization of the Flame Ionization Detection 
fuel-air ratio using methane;
    (6) A leak check;
    (7) A check to determine that station gas bottles used for 
calibration purposes are properly labelled and within the relevant 
tolerances;
    (8) Functional dynamometer checks addressing coast-down, roll speed 
and roll distance, inertia weight selection, and power absorption;
    (9) A check of the system's ability to accurately detect background 
pollutant concentrations;
    (10) A check of the pressure monitoring devices used to perform the 
evaporative canister pressure test; and
    (11) A check of the purge flow metering system.
    (d) Auditor training and proficiency. (1) Auditors shall be formally 
trained and knowledgeable in:
    (i) The use of analyzers;
    (ii) Program rules and regulations;
    (iii) The basics of air pollution control;
    (iv) Basic principles of motor vehicle engine repair, related to 
emission performance;
    (v) Emission control systems;
    (vi) Evidence gathering;
    (vii) State administrative procedures laws;
    (viii) Quality assurance practices; and
    (ix) Covert audit procedures.
    (2) Auditors shall themselves be audited at least once annually.
    (3) The training and knowledge requirements in paragraph (d)(1) of 
this section may be waived for temporary auditors engaged solely for the 
purpose of conducting covert vehicle runs.
    (e) SIP requirements. The SIP shall include a description of the 
quality assurance program, and written procedures manuals covering both 
overt and covert performance audits, record audits, and equipment 
audits. This requirement does not include materials or discussion of 
details of enforcement strategies that would ultimately hamper the 
enforcement process.



Sec. 51.364  Enforcement against contractors, stations and inspectors.

    Enforcement against licensed stations or contractors, and inspectors 
shall include swift, sure, effective, and consistent penalties for 
violation of program requirements.
    (a) Imposition of penalties. A penalty schedule shall be developed 
that establishes minimum penalties for violations of program rules and 
procedures.
    (1) The schedule shall categorize and list violations and the 
minimum penalties to be imposed for first, second, and subsequent 
violations and for multiple violation of different requirements. In the 
case of contracted systems, the State may use compensation retainage in 
lieu of penalties.
    (2) Substantial penalties or retainage shall be imposed on the first 
offense for violations that directly affect emission reduction benefits. 
At a minimum, in test-and-repair programs inspector and station license 
suspension shall be imposed for at least 6 months whenever a vehicle is 
intentionally improperly passed for any required portion of the test. In 
test-only programs, inspectors

[[Page 237]]

shall be removed from inspector duty for at least 6 months (or a 
retainage penalty equivalent to the inspector's salary for that period 
shall be imposed).
    (3) All findings of serious violations of rules or procedural 
requirements shall result in mandatory fines or retainage. In the case 
of gross neglect, a first offense shall result in a fine or retainage of 
no less than $100 or 5 times the inspection fee, whichever is greater, 
for the contractor or the licensed station, and the inspector if 
involved.
    (4) Any finding of inspector incompetence shall result in mandatory 
training before inspection privileges are restored.
    (5) License or certificate suspension or revocation shall mean the 
individual is barred from direct or indirect involvement in any 
inspection operation during the term of the suspension or revocation.
    (b) Legal authority. (1) The quality assurance officer shall have 
the authority to temporarily suspend station and inspector licenses or 
certificates (after approval of a superior) immediately upon finding a 
violation or equipment failure that directly affects emission reduction 
benefits, pending a hearing when requested. In the case of immediate 
suspension, a hearing shall be held within fourteen calendar days of a 
written request by the station licensee or the inspector. Failure to 
hold a hearing within 14 days when requested shall cause the suspension 
to lapse. In the event that a State's constitution precludes such a 
temporary license suspension, the enforcement system shall be designed 
with adequate resources and mechanisms to hold a hearing to suspend or 
revoke the station or inspector license within three station business 
days of the finding.
    (2) The oversight agency shall have the authority to impose 
penalties against the licensed station or contractor, as well as the 
inspector, even if the licensee or contractor had no direct knowledge of 
the violation but was found to be careless in oversight of inspectors or 
has a history of violations. Contractors and licensees shall be held 
fully responsible for inspector performance in the course of duty.
    (c) Recordkeeping. The oversight agency shall maintain records of 
all warnings, civil fines, suspensions, revocations, and violations and 
shall compile statistics on violations and penalties on an annual basis.
    (d) SIP requirements. (1) The SIP shall include the penalty schedule 
and the legal authority for establishing and imposing penalties, civil 
fines, license suspension, and revocations.
    (2) In the case of State constitutional impediments to immediate 
suspension authority, the State Attorney General shall furnish an 
official opinion for the SIP explaining the constitutional impediment as 
well as relevant case law.
    (3) The SIP shall describe the administrative and judicial 
procedures and responsibilities relevant to the enforcement process, 
including which agencies, courts, and jurisdictions are involved; who 
will prosecute and adjudicate cases; and other aspects of the 
enforcement of the program requirements, the resources to be allocated 
to this function, and the source of those funds. In States without 
immediate suspension authority, the SIP shall demonstrate that 
sufficient resources, personnel, and systems are in place to meet the 
three day case management requirement for violations that directly 
affect emission reductions.
    (e) Alternative quality assurance procedures or frequencies that 
achieve equivalent or better results may be approved by the 
Administrator. Statistical process control shall be used whenever 
possible to demonstrate the efficacy of alternatives.
    (f) Areas that qualify for and choose to implement an OTR low 
enhanced I/M program, as established in Sec. 51.351(h), and that claim 
in their SIP less emission reduction credit than the basic performance 
standard for one or more pollutants, are not required to meet the 
oversight specifications of this section.

[57 FR 52987, Nov. 5, 1992, as amended at 61 FR 39037, July 25, 1996]



Sec. 51.365  Data collection.

    Accurate data collection is essential to the management, evaluation, 
and enforcement of an I/M program. The

[[Page 238]]

program shall gather test data on individual vehicles, as well as 
quality control data on test equipment.
    (a) Test data. The goal of gathering test data is to unambiguously 
link specific test results to a specific vehicle, I/M program 
registrant, test site, and inspector, and to determine whether or not 
the correct testing parameters were observed for the specific vehicle in 
question. In turn, these data can be used to distinguish complying and 
noncomplying vehicles as a result of analyzing the data collected and 
comparing it to the registration database, to screen inspection stations 
and inspectors for investigation as to possible irregularities, and to 
help establish the overall effectiveness of the program. At a minimum, 
the program shall collect the following with respect to each test 
conducted:
    (1) Test record number;
    (2) Inspection station and inspector numbers;
    (3) Test system number;
    (4) Date of the test;
    (5) Emission test start time and the time final emission scores are 
determined;
    (6) Vehicle Identification Number;
    (7) License plate number;
    (8) Test certificate number;
    (9) Gross Vehicle Weight Rating (GVWR);
    (10) Vehicle model year, make, and type;
    (11) Number of cylinders or engine displacement;
    (12) Transmission type;
    (13) Odometer reading;
    (14) Category of test performed (i.e., initial test, first retest, 
or subsequent retest);
    (15) Fuel type of the vehicle (i.e., gas, diesel, or other fuel);
    (16) Type of vehicle preconditioning performed (if any);
    (17) Emission test sequence(s) used;
    (18) Hydrocarbon emission scores and standards for each applicable 
test mode;
    (19) Carbon monoxide emission scores and standards for each 
applicable test mode;
    (20) Carbon dioxide emission scores (CO+CO2) and 
standards for each applicable test mode;
    (21) Nitrogen oxides emission scores and standards for each 
applicable test mode;
    (22) Results (Pass/Fail/Not Applicable) of the applicable visual 
inspections for the catalytic converter, air system, gas cap, 
evaporative system, positive crankcase ventilation (PCV) valve, fuel 
inlet restrictor, and any other visual inspection for which emission 
reduction credit is claimed;
    (23) Results of the evaporative system pressure test expressed as a 
pass or fail;
    (24) Results of the evaporative system purge test expressed as a 
pass or fail along with the total purge flow in liters achieved during 
the test; and
    (25) Results of the on-board diagnostic check expressed as a pass or 
fail along with the diagnostic trouble codes revealed.
    (b) Quality control data. At a minimum, the program shall gather and 
report the results of the quality control checks required under 
Sec. 51.359 of this subpart, identifying each check by station number, 
system number, date, and start time. The data report shall also contain 
the concentration values of the calibration gases used to perform the 
gas characterization portion of the quality control checks.

[ 57 FR 52987, Nov. 5, 1992, as amended at 61 FR 40945, Aug. 6, 1996]



Sec. 51.366  Data analysis and reporting.

    Data analysis and reporting are required to allow for monitoring and 
evaluation of the program by program management and EPA, and shall 
provide information regarding the types of program activities performed 
and their final outcomes, including summary statistics and effectiveness 
evaluations of the enforcement mechanism, the quality assurance system, 
the quality control program, and the testing element. Initial submission 
of the following annual reports shall commence within 18 months of 
initial implementation of the program as required by Sec. 51.373 of this 
subpart. The biennial report shall commence within 30 months of initial 
implementation of the program as required by Sec. 51.373 of this 
subpart.
    (a) Test data report. The program shall submit to EPA by July of 
each

[[Page 239]]

year a report providing basic statistics on the testing program for 
January through December of the previous year, including:
    (1) The number of vehicles tested by model year and vehicle type;
    (2) By model year and vehicle type, the number and percentage of 
vehicles:
    (i) Failing the emissions test initially;
    (ii) Failing each emission control component check initially;
    (iii) Failing the evaporative system functional and integrity checks 
initially;
    (iv) Failing the first retest for tailpipe emissions;
    (v) Passing the first retest for tailpipe emissions;
    (vi) Initially failed vehicles passing the second or subsequent 
retest for tailpipe emissions;
    (vii) Initially failed vehicles passing each emission control 
component check on the first or subsequent retest by component;
    (viii) Initially failed vehicles passing the evaporative system 
functional and integrity checks on the first or subsequent retest by 
component;
    (ix) Initially failed vehicles receiving a waiver;
    (x) Vehicles with no known final outcome (regardless of reason);
    (xi) Passing the on-board diagnostic check and failing the I/M 
emission test;
    (xii) Failing the on-board diagnostic check and passing the I/M 
emission test;
    (xiii) Passing both the on-board diagnostic check and I/M emission 
test;
    (xiv) Failing both the on-board diagnostic check and I/M emission 
test;
    (xv) Passing the on-board diagnostic check and failing the I/M 
evaporative test;
    (xvi) Failing the on-board diagnostic check and passing the I/M 
evaporative test;
    (xvii) Passing both the on-board diagnostic check and I/M 
evaporative test;
    (xviii) Failing both the on-board diagnostic check and I/M 
evaporative test;
    (xix) MIL is commanded on and no codes are stored;
    (xx) MIL is not commanded on and codes are stored;
    (xxi) MIL is commanded on and codes are stored;
    (xxii) MIL is not commanded on and codes are not stored;
    (xxiii) Readiness status indicates that the evaluation is not 
complete for any module supported by on-board diagnostic systems;
    (3) The initial test volume by model year and test station;
    (4) The initial test failure rate by model year and test station; 
and
    (5) The average increase or decrease in tailpipe emission levels for 
HC, CO, and NOX (if applicable) after repairs by model year 
and vehicle type for vehicles receiving a mass emissions test.
    (b) Quality assurance report. The program shall submit to EPA by 
July of each year a report providing basic statistics on the quality 
assurance program for January through December of the previous year, 
including:
    (1) The number of inspection stations and lanes:
    (i) Operating throughout the year; and
    (ii) Operating for only part of the year;
    (2) The number of inspection stations and lanes operating throughout 
the year:
    (i) Receiving overt performance audits in the year;
    (ii) Not receiving overt performance audits in the year;
    (iii) Receiving covert performance audits in the year;
    (iv) Not receiving covert performance audits in the year; and
    (v) That have been shut down as a result of overt performance 
audits;
    (3) The number of covert audits:
    (i) Conducted with the vehicle set to fail the emission test;
    (ii) Conducted with the vehicle set to fail the component check;
    (iii) Conducted with the vehicle set to fail the evaporative system 
checks;
    (iv) Conducted with the vehicle set to fail any combination of two 
or more of the above checks;
    (v) Resulting in a false pass for emissions;
    (vi) Resulting in a false pass for component checks;
    (vii) Resulting in a false pass for the evaporative system check; 
and

[[Page 240]]

    (viii) Resulting in a false pass for any combination of two or more 
of the above checks;
    (4) The number of inspectors and stations:
    (i) That were suspended, fired, or otherwise prohibited from testing 
as a result of covert audits;
    (ii) That were suspended, fired, or otherwise prohibited from 
testing for other causes; and
    (iii) That received fines;
    (5) The number of inspectors licensed or certified to conduct 
testing;
    (6) The number of hearings:
    (i) Held to consider adverse actions against inspectors and 
stations; and
    (ii) Resulting in adverse actions against inspectors and stations;
    (7) The total amount collected in fines from inspectors and stations 
by type of violation;
    (8) The total number of covert vehicles available for undercover 
audits over the year; and
    (9) The number of covert auditors available for undercover audits.
    (c) Quality control report. The program shall submit to EPA by July 
of each year a report providing basic statistics on the quality control 
program for January through December of the previous year, including:
    (1) The number of emission testing sites and lanes in use in the 
program;
    (2) The number of equipment audits by station and lane;
    (3) The number and percentage of stations that have failed equipment 
audits; and
    (4) Number and percentage of stations and lanes shut down as a 
result of equipment audits.
    (d) Enforcement report. (1) All varieties of enforcement programs 
shall, at a minimum, submit to EPA by July of each year a report 
providing basic statistics on the enforcement program for January 
through December of the previous year, including:
    (i) An estimate of the number of vehicles subject to the inspection 
program, including the results of an analysis of the registration data 
base;
    (ii) The percentage of motorist compliance based upon a comparison 
of the number of valid final tests with the number of subject vehicles;
    (iii) The total number of compliance documents issued to inspection 
stations;
    (iv) The number of missing compliance documents;
    (v) The number of time extensions and other exemptions granted to 
motorists; and
    (vi) The number of compliance surveys conducted, number of vehicles 
surveyed in each, and the compliance rates found.
    (2) Registration denial based enforcement programs shall provide the 
following additional information:
    (i) A report of the program's efforts and actions to prevent 
motorists from falsely registering vehicles out of the program area or 
falsely changing fuel type or weight class on the vehicle registration, 
and the results of special studies to investigate the frequency of such 
activity; and
    (ii) The number of registration file audits, number of registrations 
reviewed, and compliance rates found in such audits.
    (3) Computer-matching based enforcement programs shall provide the 
following additional information:
    (i) The number and percentage of subject vehicles that were tested 
by the initial deadline, and by other milestones in the cycle;
    (ii) A report on the program's efforts to detect and enforce against 
motorists falsely changing vehicle classifications to circumvent program 
requirements, and the frequency of this type of activity; and
    (iii) The number of enforcement system audits, and the error rate 
found during those audits.
    (4) Sticker-based enforcement systems shall provide the following 
additional information:
    (i) A report on the program's efforts to prevent, detect, and 
enforce against sticker theft and counterfeiting, and the frequency of 
this type of activity;
    (ii) A report on the program's efforts to detect and enforce against 
motorists falsely changing vehicle classifications to circumvent program 
requirements, and the frequency of this type of activity; and

[[Page 241]]

    (iii) The number of parking lot sticker audits conducted, the number 
of vehicles surveyed in each, and the noncompliance rate found during 
those audits.
    (e) Additional reporting requirements. In addition to the annual 
reports in paragraphs (a) through (d) of this section, programs shall 
submit to EPA by July of every other year, biennial reports addressing:
    (1) Any changes made in program design, funding, personnel levels, 
procedures, regulations, and legal authority, with detailed discussion 
and evaluation of the impact on the program of all such changes; and
    (2) Any weaknesses or problems identified in the program within the 
two-year reporting period, what steps have already been taken to correct 
those problems, the results of those steps, and any future efforts 
planned.
    (f) SIP requirements. The SIP shall describe the types of data to be 
collected.

[ 57 FR 52987, Nov. 5, 1992, as amended at 61 FR 40945, Aug. 6, 1996]



Sec. 51.367  Inspector training and licensing or certification.

    All inspectors shall receive formal training and be licensed or 
certified to perform inspections.
    (a) Training. (1) Inspector training shall impart knowledge of the 
following:
    (i) The air pollution problem, its causes and effects;
    (ii) The purpose, function, and goal of the inspection program;
    (iii) Inspection regulations and procedures;
    (iv) Technical details of the test procedures and the rationale for 
their design;
    (v) Emission control device function, configuration, and inspection;
    (vi) Test equipment operation, calibration, and maintenance;
    (vii) Quality control procedures and their purpose;
    (viii) Public relations; and
    (ix) Safety and health issues related to the inspection process.
    (2) If inspector training is not administered by the program, the 
responsible State agency shall monitor and evaluate the training program 
delivery.
    (3) In order to complete the training requirement, a trainee shall 
pass (i.e., a minimum of 80% of correct responses or lower if an 
occupational analysis justifies it) a written test covering all aspects 
of the training. In addition, a hands-on test shall be administered in 
which the trainee demonstrates without assistance the ability to conduct 
a proper inspection, to properly utilize equipment and to follow other 
procedures. Inability to properly conduct all test procedures shall 
constitute failure of the test. The program shall take appropriate steps 
to insure the security and integrity of the testing process.
    (b) Licensing and certification. (1) All inspectors shall be either 
licensed by the program (in the case of test-and-repair systems that do 
not use contracts with stations) or certified by an organization other 
than the employer (in test-only programs and test-and-repair programs 
that require station owners to enter into contracts with the State) in 
order to perform official inspections.
    (2) Completion of inspector training and passing required tests 
shall be a condition of licensing or certification.
    (3) Inspector licenses and certificates shall be valid for no more 
than 2 years, at which point refresher training and testing shall be 
required prior to renewal. Alternative approaches based on more 
comprehensive skill examination and determination of inspector 
competency may be used.
    (4) Licenses or certificates shall not be considered a legal right 
but rather a privilege bestowed by the program conditional upon 
adherence to program requirements.
    (c) SIP requirements. The SIP shall include a description of the 
training program, the written and hands-on tests, and the licensing or 
certification process.



Sec. 51.368  Public information and consumer protection.

    (a) Public awareness. The SIP shall include a plan for informing the 
public on an ongoing basis throughout the life of the I/M program of the 
air quality problem, the requirements of Federal and State law, the role 
of motor vehicles in the air quality problem, the need for and benefits 
of an inspection program, how to maintain a vehicle in

[[Page 242]]

a low-emission condition, how to find a qualified repair technician, and 
the requirements of the I/M program. Motorists that fail the I/M test in 
enhanced I/M areas shall be offered a list of repair facilities in the 
area and information on the results of repairs performed by repair 
facilities in the area, as described in Sec. 51.369(b)(1) of this 
subpart. Motorists that fail the I/M test shall also be provided with 
software-generated, interpretive diagnostic information based on the 
particular portions of the test that were failed.
    (b) Consumer protection. The oversight agency shall institute 
procedures and mechanisms to protect the public from fraud and abuse by 
inspectors, mechanics, and others involved in the I/M program. This 
shall include a challenge mechanism by which a vehicle owner can contest 
the results of an inspection. It shall include mechanisms for protecting 
whistle blowers and following up on complaints by the public or others 
involved in the process. It shall include a program to assist owners in 
obtaining warranty covered repairs for eligible vehicles that fail a 
test. The SIP shall include a detailed consumer protection plan.



Sec. 51.369  Improving repair effectiveness.

    Effective repairs are the key to achieving program goals and the 
State shall take steps to ensure the capability exists in the repair 
industry to repair vehicles that fail I/M tests.
    (a) Technical assistance. The oversight agency shall provide the 
repair industry with information and assistance related to vehicle 
inspection diagnosis and repair.
    (1) The agency shall regularly inform repair facilities of changes 
in the inspection program, training course schedules, common problems 
being found with particular engine families, diagnostic tips and the 
like.
    (2) The agency shall provide a hot line service to assist repair 
technicians with specific repair problems, answer technical questions 
that arise in the repair process, and answer questions related to the 
legal requirements of State and Federal law with regard to emission 
control device tampering, engine switching, or similar issues.
    (b) Performance monitoring. (1) In enhanced I/M program areas, the 
oversight agency shall monitor the performance of individual motor 
vehicle repair facilities, and provide to the public at the time of 
initial failure, a summary of the performance of local repair facilities 
that have repaired vehicles for retest. Performance monitoring shall 
include statistics on the number of vehicles submitted for a retest 
after repair by the repair facility, the percentage passing on first 
retest, the percentage requiring more than one repair/retest trip before 
passing, and the percentage receiving a waiver. Programs may provide 
motorists with alternative statistics that convey similar information on 
the relative ability of repair facilities in providing effective and 
convenient repair, in light of the age and other characteristics of 
vehicles presented for repair at each facility.
    (2) Programs shall provide feedback, including statistical and 
qualitative information to individual repair facilities on a regular 
basis (at least annually) regarding their success in repairing failed 
vehicles.
    (3) A prerequisite for a retest shall be a completed repair form 
that indicates which repairs were performed, as well as any technician 
recommended repairs that were not performed, and identification of the 
facility that performed the repairs.
    (c) Repair technician training. The State shall assess the 
availability of adequate repair technician training in the I/M area and, 
if the types of training described in paragraphs (c)(1) through (4) of 
this section are not currently available, shall insure that training is 
made available to all interested individuals in the community either 
through private or public facilities. This may involve working with 
local community colleges or vocational schools to add curricula to 
existing programs or start new programs or it might involve attracting 
private training providers to offer classes in the area. The training 
available shall include:
    (1) Diagnosis and repair of malfunctions in computer controlled, 
close-loop vehicles;

[[Page 243]]

    (2) The application of emission control theory and diagnostic data 
to the diagnosis and repair of failures on the transient emission test 
and the evaporative system functional checks;
    (3) Utilization of diagnostic information on systematic or repeated 
failures observed in the transient emission test and the evaporative 
system functional checks; and
    (4) General training on the various subsystems related to engine 
emission control.
    (d) SIP requirements. The SIP shall include a description of the 
technical assistance program to be implemented, a description of the 
procedures and criteria to be used in meeting the performance monitoring 
requirements of this section, and a description of the repair technician 
training resources available in the community.



Sec. 51.370  Compliance with recall notices.

    States shall establish methods to ensure that vehicles subject to 
enhanced I/M and that are included in either a ``Voluntary Emissions 
Recall'' as defined at 40 CFR 85.1902(d), or in a remedial plan 
determination made pursuant to section 207(c) of the Act, receive the 
required repairs. States shall require that owners of recalled vehicles 
have the necessary recall repairs completed, either in order to complete 
an annual or biennial inspection process or to obtain vehicle 
registration renewal. All recalls for which owner notification occurs 
after January 1, 1995 shall be included in the enhanced I/M recall 
requirement.
    (a) General requirements. (1) The State shall have an electronic 
means to identify recalled vehicles based on lists of VINs with 
unresolved recalls made available by EPA, the vehicle manufacturers, or 
a third party supplier approved by the Administrator. The State shall 
update its list of unresolved recalls on a quarterly basis at a minimum.
    (2) The State shall require owners or lessees of vehicles with 
unresolved recalls to show proof of compliance with recall notices in 
order to complete either the inspection or registration cycle.
    (3) Compliance shall be required on the next registration or 
inspection date, allowing a reasonable period to comply, after 
notification of recall was received by the State.
    (b) Enforcement. (1) A vehicle shall either fail inspection or be 
denied vehicle registration if the required recall repairs have not been 
completed.
    (2) In the case of vehicles obtaining recall repairs but remaining 
on the updated list provided in paragraph (a)(1) of this section, the 
State shall have a means of verifying completion of the required 
repairs; electronic records or paper receipts provided by the authorized 
repair facility shall be required. The vehicle inspection or 
registration record shall be modified to include (or be supplemented 
with other VIN-linked records which include) the recall campaign 
number(s) and the date(s) repairs were performed. Documentation 
verifying required repairs shall include the following:
    (i) The VIN, make, and model year of the vehicle; and
    (ii) The recall campaign number and the date repairs were completed.
    (c) Reporting requirements. The State shall submit to EPA, by July 
of each year for the previous calendar year, an annual report providing 
the following information:
    (1) The number of vehicles in the I/M area initially listed as 
having unresolved recalls, segregated by recall campaign number;
    (2) The number of recalled vehicles brought into compliance by 
owners;
    (3) The number of listed vehicles with unresolved recalls that, as 
of the end of the calendar year, were not yet due for inspection or 
registration;
    (4) The number of recalled vehicles still in non-compliance that 
have either failed inspection or been denied registration on the basis 
of non-compliance with recall; and
    (5) The number of recalled vehicles that are otherwise not in 
compliance.
    (d) SIP submittals. The SIP shall describe the procedures used to 
incorporate the vehicle lists provided in paragraph (a)(1) of this 
section into the inspection or registration database, the quality 
control methods used to insure that recall repairs are properly 
documented and tracked, and the method

[[Page 244]]

(inspection failure or registration denial) used to enforce the recall 
requirements.



Sec. 51.371  On-road testing.

    On-road testing is defined as the measurement of HC, CO, 
NOX, and/or CO2 emissions on any road or roadside 
in the nonattainment area or the I/M program area. On-road testing is 
required in enhanced I/M areas and is an option for basic I/M areas.
    (a) General requirements. (1) On-road testing is to be part of the 
emission testing system, but is to be a complement to testing otherwise 
required.
    (2) On-road testing is not required in every season or on every 
vehicle but shall evaluate the emission performance of 0.5% of the 
subject fleet statewide or 20,000 vehicles, whichever is less, including 
any vehicles that may be subject to the follow-up inspection provisions 
of paragraph (a)(4) of this section, each inspection cycle.
    (3) The on-road testing program shall provide information about the 
emission performance of in-use vehicles, by measuring on-road emissions 
through the use of remote sensing devices or roadside pullovers 
including tailpipe emission testing. The program shall collect, analyze 
and report on-road testing data.
    (4) Owners of vehicles that have previously been through the normal 
periodic inspection and passed the final retest and found to be high 
emitters shall be notified that the vehicles are required to pass an 
out-of-cycle follow-up inspection; notification may be by mailing in the 
case of remote sensing on-road testing or through immediate notification 
if roadside pullovers are used.
    (b) SIP requirements. (1) The SIP shall include a detailed 
description of the on-road testing program, including the types of 
testing, test limits and criteria, the number of vehicles (the 
percentage of the fleet) to be tested, the number of employees to be 
dedicated to the on-road testing effort, the methods for collecting, 
analyzing, utilizing, and reporting the results of on-road testing and, 
the portion of the program budget to be dedicated to on-road testing.
    (2) The SIP shall include the legal authority necessary to implement 
the on-road testing program, including the authority to enforce off-
cycle inspection and repair requirements.
    (3) Emission reduction credit for on-road testing programs shall be 
granted for a program designed to obtain significant emission reductions 
over and above those already predicted to be achieved by other aspects 
of the I/M program. The SIP shall include technical support for the 
claimed additional emission reductions.



Sec. 51.372  State Implementation Plan submissions.

    (a) SIP submittals. The SIP shall address each of the elements 
covered in this subpart, including, but not limited to:
    (1) A schedule of implementation of the program including interim 
milestones leading to mandatory testing. The milestones shall include, 
at a minimum:
    (i) Passage of enabling statutory or other legal authority;
    (ii) Proposal of draft regulations and promulgation of final 
regulations;
    (iii) Issuance of final specifications and procedures;
    (iv) Issuance of final Request for Proposals (if applicable);
    (v) Licensing or certifications of stations and inspectors;
    (vi) The date mandatory testing will begin for each model year to be 
covered by the program;
    (vii) The date full-stringency cutpoints will take effect;
    (viii) All other relevant dates;
    (2) An analysis of emission level targets for the program using the 
most current EPA mobile source emission model or an alternative approved 
by the Administrator showing that the program meets the performance 
standard described in Sec. 51.351 or Sec. 51.352 of this subpart, as 
applicable;
    (3) A description of the geographic coverage of the program, 
including ZIP codes if the program is not county-wide;
    (4) A detailed discussion of each of the required design elements, 
including provisions for Federal facility compliance;

[[Page 245]]

    (5) Legal authority requiring or allowing implementation of the I/M 
program and providing either broad or specific authority to perform all 
required elements of the program;
    (6) Legal authority for I/M program operation until such time as it 
is no longer necessary (i.e., until a Section 175 maintenance plan 
without an I/M program is approved by EPA);
    (7) Implementing regulations, interagency agreements, and memoranda 
of understanding; and
    (8) Evidence of adequate funding and resources to implement all 
aspects of the program.
    (b) Submittal schedule. The SIP shall be submitted to EPA according 
to the following schedule--
    (1) States shall submit a SIP revision by November 15, 1992 which 
includes the schedule required in paragraph (a)(1) of this section and a 
formal commitment from the Governor to the adoption and implementation 
of an I/M program meeting all requirements of this subpart.
    (2) A SIP revision, including all necessary legal authority and the 
items specified in (a)(1) through (a)(8) of this section, shall be 
submitted no later than November 15, 1993.
    (3) States shall revise SIPS as EPA develops further regulations. 
Revisions to incorporate on-board diagnostic checks in the I/M program 
shall be submitted by August 6, 1998.
    (c) Redesignation requests. Any nonattainment area that EPA 
determines would otherwise qualify for redesignation from nonattainment 
to attainment shall receive full approval of a State Implementation Plan 
(SIP) submittal under Sections 182(a)(2)(B) or 182(b)(4) if the 
submittal contains the following elements:
    (1) Legal authority to implement a basic I/M program (or enhanced if 
the State chooses to opt up) as required by this subpart. The 
legislative authority for an I/M program shall allow the adoption of 
implementing regulations without requiring further legislation.
    (2) A request to place the I/M plan (if no I/M program is currently 
in place or if an I/M program has been terminated,) or the I/M upgrade 
(if the existing I/M program is to continue without being upgraded) into 
the contingency measures portion of the maintenance plan upon 
redesignation.
    (3) A contingency measure consisting of a commitment by the Governor 
or the Governor's designee to adopt or consider adopting regulations to 
implement an I/M program to correct a violation of the ozone or CO 
standard or other air quality problem, in accordance with the provisions 
of the maintenance plan.
    (4) A contingency commitment that includes an enforceable schedule 
for adoption and implementation of the I/M program, and appropriate 
milestones. The schedule shall include the date for submission of a SIP 
meeting all of the requirements of this subpart. Schedule milestones 
shall be listed in months from the date EPA notifies the State that it 
is in violation of the ozone or CO standard or any earlier date 
specified in the State plan. Unless the State, in accordance with the 
provisions of the maintenance plan, chooses not to implement I/M, it 
must submit a SIP revision containing an I/M program no more than 18 
months after notification by EPA.
    (d) Basic areas continuing operation of I/M programs as part of 
their maintenance plan without implemented upgrades shall be assumed to 
be 80% as effective as an implemented, upgraded version of the same I/M 
program design, unless a State can demonstrate using operating 
information that the I/M program is more effective than the 80% level.
    (e) SIP submittals to correct violations. SIP submissions required 
pursuant to a violation of the ambient ozone or CO standard (as 
discussed in paragraph (c) of this section) shall address all of the 
requirements of this subpart. The SIP shall demonstrate that performance 
standards in either Sec. 51.351 or Sec. 51.352 shall be met using an 
evaluation date (rounded to the nearest January for carbon monoxide and 
July for hydrocarbons) seven years after the date EPA notifies the State 
that it is in violation of the ozone or CO standard or any earlier date 
specified in the State plan. Emission standards for vehicles subject to 
an IM240 test may be phased in during the program but full standards 
must be in effect for at least one complete test cycle before the end of

[[Page 246]]

the 5-year period. All other requirements shall take effect within 24 
months of the date EPA notifies the State that it is in violation of the 
ozone or CO standard or any earlier date specified in the State plan. 
The phase-in allowances of Sec. 51.373(c) of this subpart shall not 
apply.

[57 FR 52987, Nov. 5, 1992, as amended at 60 FR 1738, Jan. 5, 1995; 60 
FR 48036, Sept. 18, 1995; 61 FR 40946, Aug. 6, 1996; 61 FR 44119, Aug. 
27, 1996]



Sec. 51.373  Implementation deadlines.

    I/M programs shall be implemented as expeditiously as practicable.
    (a) Decentralized basic programs shall be fully implemented by 
January 1, 1994, and centralized basic programs shall be fully 
implemented by July 1, 1994. More implementation time may be approved by 
the Administrator if an enhanced I/M program is implemented.
    (b) For areas newly required to implement basic I/M after 
promulgation of this subpart (as a result of failure to attain, 
reclassification, or redesignation) decentralized programs shall be 
fully implemented within one year of obtaining legal authority. 
Centralized programs shall be fully implemented within two years of 
obtaining legal authority. More implementation time may be approved by 
the Administrator if an enhanced I/M program is implemented.
    (c) All requirements related to enhanced I/M programs shall be 
implemented by January 1, 1995, with the following exceptions.
    (1) Areas switching from an existing test-and-repair network to a 
test-only network may phase in the change between January of 1995 and 
January of 1996. Starting in January of 1995 at least 30% of the subject 
vehicles shall participate in the test-only system (in States with 
multiple I/M areas, implementation is not required in every area by 
January 1995 as long as statewide, 30% of the subject vehicles are 
involved in testing) and shall be subject to the new test procedures 
(including the evaporative system checks, visual inspections, and 
tailpipe emission tests). By January 1, 1996, all applicable vehicle 
model years and types shall be included in the test-only system. During 
the phase-in period, all requirements of this subpart shall be applied 
to the test-only portion of the program; existing requirements may 
continue to apply for the test-and-repair portion of the program until 
it is phased out by January 1, 1996.
    (2) Areas starting new test-only programs and those with existing 
test-only programs may also phase in the new test procedures between 
January 1, 1995 and January 1, 1996. Other program requirements shall be 
fully implemented by January 1, 1995.
    (d) In the case of areas newly required to implement enhanced I/M 
after promulgation of this subpart (as a result of failure to attain, 
reclassification, or nonattainment designation) enhanced I/M shall be 
implemented within 24 months of obtaining legal authority.
    (e) Legal authority for the implementing agency or agencies to 
implement and enforce an I/M program consistent with this subpart shall 
be obtained from the State legislature or local governing body in the 
first legislative session after November 5, 1992, or after being newly 
required to implement or upgrade an I/M program as in paragraph (b) or 
(c) of this section, including sessions already in progress if at least 
21 days remain before the final bill submittal deadline.
    (f) Areas that choose to implement an enhanced I/M program only 
meeting the requirements of Sec. 51.351(h) shall fully implement the 
program no later than July 1, 1999. The availability and use of this 
late start date does not relieve the area of the obligation to meet the 
requirements of Sec. 51.351(h)(11) by the end of 1999.
    (g) On-Board Diagnostic checks shall be implemented in all basic, 
low enhanced and high enhanced areas as part of the I/M program by 
January 1, 2001.

[57 FR 52987, Nov. 5, 1992, as amended at 58 FR 59367, Nov. 9, 1993; 61 
FR 39037, July 25, 1996; 61 FR 40946, Aug. 6, 1996; 63 FR 24433, May 4, 
1998]

 Appendix A to Subpart S--Calibrations, Adjustments and Quality Control

                     (I) Steady-State Test Equipment

    States may opt to use transient emission test equipment for steady-
state tests and follow the quality control requirements in

[[Page 247]]

paragraph (II) of this appendix instead of the following requirements.
    (a) Equipment shall be calibrated in accordance with the 
manufacturers' instructions.
    (b) Prior to each test. (1) Hydrocarbon hang-up check. Immediately 
prior to each test the analyzer shall automatically perform a 
hydrocarbon hang-up check. If the HC reading, when the probe is sampling 
ambient air, exceeds 20 ppm, the system shall be purged with clean air 
or zero gas. The analyzer shall be inhibited from continuing the test 
until HC levels drop below 20 ppm.
    (2) Automatic zero and span. The analyzer shall conduct an automatic 
zero and span check prior to each test. The span check shall include the 
HC, CO, and CO2 channels, and the NO and O2 channels, if 
present. If zero and/or span drift cause the signal levels to move 
beyond the adjustment range of the analyzer, it shall lock out from 
testing.
    (3) Low flow. The system shall lock out from testing if sample flow 
is below the acceptable level as defined in paragraph (I)(b)(6) of 
appendix D to this subpart.
    (c) Leak check. A system leak check shall be performed within 
twenty-four hours before the test in low volume stations (those 
performing less than the 4,000 inspections per year) and within four 
hours in high-volume stations (4,000 or more inspections per year) and 
may be performed in conjunction with the gas calibration described in 
paragraph (I)(d)(1) of this appendix. If a leak check is not performed 
within the preceding twenty-four hours in low volume stations and within 
four hours in high-volume stations or if the analyzer fails the leak 
check, the analyzer shall lock out from testing. The leak check shall be 
a procedure demonstrated to effectively check the sample hose and probe 
for leaks and shall be performed in accordance with good engineering 
practices. An error of more than 2% of the reading using low 
range span gas shall cause the analyzer to lock out from testing and 
shall require repair of leaks.
    (d) Gas calibration. (1) On each operating day in high-volume 
stations, analyzers shall automatically require and successfully pass a 
two-point gas calibration for HC, CO, and CO2 and shall continually 
compensate for changes in barometric pressure. Calibration shall be 
checked within four hours before the test and the analyzer adjusted if 
the reading is more than 2% different from the span gas value. In low-
volume stations, analyzers shall undergo a two-point calibration within 
seventy-two hours before each test, unless changes in barometric 
pressure are compensated for automatically and statistical process 
control demonstrates equal or better quality control using different 
frequencies. Gas calibration shall be accomplished by introducing span 
gas that meets the requirements of paragraph (I)(d)(3) of this appendix 
into the analyzer through the calibration port. If the analyzer reads 
the span gas within the allowable tolerance range (i.e., the square root 
of sum of the squares of the span gas tolerance described in paragraph 
(I)(d)(3) of this appendix and the calibration tolerance, which shall be 
equal to 2%), no adjustment of the analyzer is necessary. The gas 
calibration procedure shall correct readings that exceed the allowable 
tolerance range to the center of the allowable tolerance range. The 
pressure in the sample cell shall be the same with the calibration gas 
flowing during calibration as with the sample gas flowing during 
sampling. If the system is not calibrated, or the system fails the 
calibration check, the analyzer shall lock out from testing.
    (2) Span points. A two point gas calibration procedure shall be 
followed. The span shall be accomplished at one of the following pairs 
of span points:

(A) 300--ppm propane (HC)
1.0--% carbon monoxide (CO)
6.0--% carbon dioxide (CO2)
1000--ppm nitric oxide (if equipped with NO)
1200--ppm propane (HC)
4.0--% carbon monoxide (CO)
12.0--% carbon dioxide (CO2)
3000--ppm nitric oxide (if equipped with NO)
(B) --ppm propane
0.0--% carbon monoxide
0.0--% carbon dioxide
0--ppm nitric oxide (if equipped with NO)
600--ppm propane (HC)
1.6--% carbon monoxide (CO)
11.0--% carbon dioxide (CO2)
1200--ppm nitric oxide (if equipped with NO)

    (3) Span gases. The span gases used for the gas calibration shall be 
traceable to National Institute of Standards and Technology (NIST) 
standards 2%, and shall be within two percent of the span 
points specified in paragraph (d)(2) of this appendix. Zero gases shall 
conform to the specifications given in Sec. 86.114-79(a)(5) of this 
chapter.
    (e) Dynamometer checks--(1) Monthly check. Within one month 
preceding each loaded test, the accuracy of the roll speed indicator 
shall be verified and the dynamometer shall be checked for proper power 
absorber settings.
    (2) Semi-annual check. Within six months preceding each loaded test, 
the road-load response of the variable-curve dynamometer or the 
frictional power absorption of the dynamometer shall be checked by a 
coast down procedure similar to that described in Sec. 86.118-78 of this 
chapter. The check shall be done at 30 mph, and a power absorption load 
setting to generate a total horsepower (hp) of 4.1 hp. The actual coast 
down time from 45 mph to 15 mph shall be within 1 second of 
the time calculated by the following equation:

[[Page 248]]

[GRAPHIC] [TIFF OMITTED] TC08NO91.014

where W is the total inertia weight as represented by the weight of the 
rollers (excluding free rollers), and any inertia flywheels used, 
measured in pounds. If the coast down time is not within the specified 
tolerance the dynamometer shall be taken out of service and corrective 
action shall be taken.
    (f) Other checks. In addition to the above periodic checks, these 
shall also be used to verify system performance under the following 
special circumstances.
    (1) Gas Calibration. (A) Each time the analyzer electronic or 
optical systems are repaired or replaced, a gas calibration shall be 
performed prior to returning the unit to service.
    (B) In high-volume stations, monthly multi-point calibrations shall 
be performed. Low-volume stations shall perform multi-point calibrations 
every six months. The calibration curve shall be checked at 20%, 40%, 
60%, and 80% of full scale and adjusted or repaired if the 
specifications in appendix D(I)(b)(1) to this subpart are not met.
    (2) Leak checks. Each time the sample line integrity is broken, a 
leak check shall be performed prior to testing.

                      (II) Transient Test Equipment

    (a) Dynamometer. Once per week, the calibration of each dynamometer 
and each fly wheel shall be checked by a dynamometer coast-down 
procedure comparable to that in Sec. 86.118-78 of this chapter between 
the speeds of 55 to 45 mph, and between 30 to 20 mph. All rotating 
dynamometer components shall be included in the coast-down check for the 
inertia weight selected. For dynamometers with uncoupled rolls, the 
uncoupled rollers may undergo a separate coast-down check. If a vehicle 
is used to motor the dynamometer to the beginning coast-down speed, the 
vehicle shall be lifted off the dynamometer rolls before the coast-down 
test begins. If the difference between the measured coast-down time and 
the theoretical coast-down time is greater than +1 second, the system 
shall lock out, until corrective action brings the dynamometer into 
calibration.
    (b) Constant volume sampler. (1) The constant volume sampler (CVS) 
flow calibration shall be checked daily by a procedure that identifies 
deviations in flow from the true value. Deviations greater than 
4% shall be corrected.
    (2) The sample probe shall be cleaned and checked at least once per 
month. The main CVS venturi shall be cleaned and checked at least once 
per year.
    (3) Verification that flow through the sample probe is adequate for 
the design shall be done daily. Deviations greater than the design 
tolerances shall be corrected.
    (c) Analyzer system--(1) Calibration checks. (A) Upon initial 
operation, calibration curves shall be generated for each analyzer. The 
calibration curve shall consider the entire range of the analyzer as one 
curve. At least 6 calibration points plus zero shall be used in the 
lower portion of the range corresponding to an average concentration of 
approximately 2 gpm for HC, 30 gpm for CO, 3 gpm for NOX, and 
400 gpm for CO2. For the case where a low and a high range 
analyzer is used, the high range analyzer shall use at least 6 
calibration points plus zero in the lower portion of the high range 
scale corresponding to approximately 100% of the full-scale value of the 
low range analyzer. For all analyzers, at least 6 calibration points 
shall also be used to define the calibration curve in the region above 
the 6 lower calibration points. Gas dividers may be used to obtain the 
intermediate points for the general range classifications specified. The 
calibration curves generated shall be a polynomial of no greater order 
than 4th order, and shall fit the date within 0.5% at each calibration 
point.
    (B) For all calibration curves, curve checks, span adjustments, and 
span checks, the zero gas shall be considered a down-scale reference 
gas, and the analyzer zero shall be set at the trace concentration value 
of the specific zero gas used.
    (2) The basic curve shall be checked monthly by the same procedure 
used to generate the curve, and to the same tolerances.
    (3) On a daily basis prior to vehicle testing--
    (A) The curve for each analyzer shall be checked by adjusting the 
analyzer to correctly read a zero gas and an up-scale span gas, and then 
by correctly reading a mid-scale span gas within 2% of point. If the 
analyzer does not read the mid-scale span point within 2% of point, the 
system shall lock out. The up-scale span gas concentration for each 
analyzer shall correspond to approximately 80 percent of full scale, and 
the mid-point concentration shall correspond to approximately 15 percent 
of full scale; and
    (B) After the up-scale span check, each analyzer in a given facility 
shall analyze a sample of a random concentration corresponding to 
approximately 0.5 to 3 times the cut point (in gpm) for the constituent. 
The value of the random sample may be determined by a gas blender. The 
deviation in analysis from the sample concentration for each analyzer 
shall be recorded and compared to the historical mean and standard 
deviation for the analyzers at the facility and at all facilities. Any 
reading exceeding 3 sigma shall cause the analyzer to lock out.
    (4) Flame ionization detector check. Upon initial operation, and 
after maintenance to the detector, each Flame Ionization Detector

[[Page 249]]

(FID) shall be checked, and adjusted if necessary, for proper peaking 
and characterization. Procedures described in SAE Paper No. 770141 are 
recommended for this purpose. A copy of this paper may be obtained from 
the Society of Automotive Engineers, Inc. (SAE), 400 Commonwealth Drive, 
Warrendale, Pennsylvania, 15096-0001. Additionally, every month the 
response of each FID to a methane concentration of approximately 50 ppm 
CH4 shall be checked. If the response is outside of the range 
of 1.10 to 1.20, corrective action shall be taken to bring the FID 
response within this range. The response shall be computed by the 
following formula:
[GRAPHIC] [TIFF OMITTED] TC08NO91.015

    (5) Spanning frequency. The zero and up-scale span point shall be 
checked, and adjusted if necessary, at 2 hour intervals following the 
daily mid-scale curve check. If the zero or the up-scale span point 
drifts by more than 2% for the previous check (except for the first 
check of the day), the system shall lock out, and corrective action 
shall be taken to bring the system into compliance.
    (6) Spanning limit checks. The tolerance on the adjustment of the 
up-scale span point is 0.4% of point. A software algorithm to perform 
the span adjustment and subsequent calibration curve adjustment shall be 
used. However, software up-scale span adjustments greater than 
10% shall cause the system to lock out, requiring system 
maintenance.
    (7) Integrator checks. Upon initial operation, and every three 
months thereafter, emissions from a randomly selected vehicle with 
official test value greater than 60% of the standard (determined 
retrospectively) shall be simultaneously sampled by the normal 
integration method and by the bag method in each lane. The data from 
each method shall be put into a historical data base for determining 
normal and deviant performance for each test lane, facility, and all 
facilities combined. Specific deviations exceeding 5% shall 
require corrective action.
    (8) Interference. CO and CO2 analyzers shall be checked 
prior to initial service, and on a yearly basis thereafter, for water 
interference. The specifications and procedures used shall generally 
comply with either Sec. 86.122-78 or Sec. 86.321-79 of this chapter.
    (9) NOX converter check. The converter efficiency of the 
NO2 to NO converter shall be checked on a weekly basis. The 
check shall generally conform to Sec. 86.123-78 of this chapter, or EPA 
MVEL Form 305-01. Equivalent methods may be approved by the 
Administrator.
    (10) NO/NOX flow balance. The flow balance between the NO 
and NOX test modes shall be checked weekly. The check may be 
combined with the NOX convertor check as illustrated in EPA 
MVEL Form 305-01.
    (11) Additional checks. Additional checks shall be performed on the 
HC, CO, CO2, and NOX analyzers according to best 
engineering practices for the measurement technology used to ensure that 
measurements meet specified accuracy requirements.
    (12) System artifacts (hang-up). Prior to each test a comparison 
shall be made between the background HC reading, the HC reading measured 
through the sample probe (if different), and the zero gas. Deviations 
from the zero gas greater than 10 parts per million carbon (ppmC) shall 
cause the analyzer to lock out.
    (13) Ambient background. The average of the pre-test and post-test 
ambient background levels shall be compared to the permissible levels of 
10 ppmC HC, 20 ppm CO, and 1 ppm NOX. If the permissible 
levels are exceeded, the test shall be voided and corrective action 
taken to lower the ambient background concentrations.
    (14) Analytical gases. Zero gases shall meet the requirements of 
Sec. 86.114-79(a)(5) of this chapter. NOX calibration gas 
shall be a single blend using nitrogen as the diluent. Calibration gas 
for the flame ionization detector shall be a single blend of propane 
with a diluent of air. Calibration gases for CO and CO2 shall 
be single blends using nitrogen or air as a diluent. Multiple blends of 
HC, CO, and CO2 in air may be used if shown to be stable and 
accurate.

                       (III) Purge Analysis System

    On a daily basis each purge flow meter shall be checked with a 
simulated purge flow against a reference flow measuring device with 
performance specifications equal to or better than those specified for 
the purge meter. The check shall include a mid-scale rate check, and a 
total flow check between 10 and 20 liters. Deviations greater than 
5% shall be corrected. On a monthly basis, the calibration 
of purge meters shall be checked for proper rate and total flow with 
three equally spaced points across the flow rate and the totalized flow 
range. Deviations exceeding the specified accuracy shall be corrected. 
The dynamometer quality assurance checks required under paragraph (II) 
of this

[[Page 250]]

appendix shall also apply to the dynamometer used for purge tests.

            (IV) Evaporative System Integrity Test Equipment

    (a) On a weekly basis pressure measurement devices shall be checked 
against a reference device with performance specifications equal to or 
better than those specified for the measurement device. Deviations 
exceeding the performance specifications shall be corrected. Flow 
measurement devices, if any, shall be checked according to paragraph III 
of this appendix.
    (b) Systems that monitor evaporative system leaks shall be checked 
for integrity on a daily basis by sealing and pressurizing.

[57 FR 52987, Nov. 5, 1992, as amended at 58 FR 59367, Nov. 9, 1993]

                Appendix B to Subpart S--Test Procedures

                              (I) Idle test

    (a) General requirements--(1) Exhaust gas sampling algorithm. The 
analysis of exhaust gas concentrations shall begin 10 seconds after the 
applicable test mode begins. Exhaust gas concentrations shall be 
analyzed at a minimum rate of two times per second. The measured value 
for pass/fail determinations shall be a simple running average of the 
measurements taken over five seconds.
    (2) Pass/fail determination. A pass or fail determination shall be 
made for each applicable test mode based on a comparison of the short 
test standards contained in appendix C to this subpart, and the measured 
value for HC and CO as described in paragraph (I)(a)(1) of this 
appendix. A vehicle shall pass the test mode if any pair of simultaneous 
measured values for HC and CO are below or equal to the applicable short 
test standards. A vehicle shall fail the test mode if the values for 
either HC or CO, or both, in all simultaneous pairs of values are above 
the applicable standards.
    (3) Void test conditions. The test shall immediately end and any 
exhaust gas measurements shall be voided if the measured concentration 
of CO plus CO2 falls below six percent or the vehicle's 
engine stalls at any time during the test sequence.
    (4) Multiple exhaust pipes. Exhaust gas concentrations from vehicle 
engines equipped with multiple exhaust pipes shall be sampled 
simultaneously.
    (5) This test shall be immediately terminated upon reaching the 
overall maximum test time.
    (b) Test sequence. (1) The test sequence shall consist of a first-
chance test and a second-chance test as follows:
    (i) The first-chance test, as described under paragraph (c) of this 
section, shall consist of an idle mode.
    (ii) The second-chance test as described under paragraph (I)(d) of 
this appendix shall be performed only if the vehicle fails the first-
chance test.
    (2) The test sequence shall begin only after the following 
requirements are met:
    (i) The vehicle shall be tested in as-received condition with the 
transmission in neutral or park and all accessories turned off. The 
engine shall be at normal operating temperature (as indicated by a 
temperature gauge, temperature lamp, touch test on the radiator hose, or 
other visual observation for overheating).
    (ii) For all pre-1996 model year vehicles, a tachometer shall be 
attached to the vehicle in accordance with the analyzer manufacturer's 
instructions. For 1996 and newer model year vehicles the OBD data link 
connector will be used to monitor RPM. In the event that an OBD data 
link connector is not available or that an RPM signal is not available 
over the data link connector, a tachometer shall be used instead.
    (iii) The sample probe shall be inserted into the vehicle's tailpipe 
to a minimum depth of 10 inches. If the vehicle's exhaust system 
prevents insertion to this depth, a tailpipe extension shall be used.
    (iv) The measured concentration of CO plus CO2 shall be 
greater than or equal to six percent.
    (c) First-chance test. The test timer shall start (tt=0) when the 
conditions specified in paragraph (I)(b)(2) of this appendix are met. 
The first-chance test shall have an overall maximum test time of 145 
seconds (tt=145). The first-chance test shall consist of an idle mode 
only.
    (1) The mode timer shall start (mt=0) when the vehicle engine speed 
is between 350 and 1100 rpm. If engine speed exceeds 1100 rpm or falls 
below 350 rpm, the mode timer shall reset zero and resume timing. The 
minimum mode length shall be determined as described under paragraph 
(I)(c)(2) of this appendix. The maximum mode length shall be 90 seconds 
elapsed time (mt=90).
    (2) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt=10). A pass or fail determination shall be made for the 
vehicle and the mode shall be terminated as follows:
    (i) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, prior to an elapsed time of 30 seconds 
(mt=30), measured values are less than or equal to 100 ppm HC and 0.5 
percent CO.
    (ii) The vehicle shall pass the idle mode and the test shall be 
terminated at the end of an elapsed time of 30 seconds (mt=30), if prior 
to that time the criteria of paragraph (I)(c)(2)(i) of this appendix are 
not satisfied and the measured values are less than or equal to the 
applicable short test standards as described in paragraph (I)(a)(2) of 
this appendix.

[[Page 251]]

    (iii) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, at any point between an elapsed time of 30 
seconds (mt=30) and 90 seconds (mt=90), the measured values are less 
than or equal to the applicable short test standards as described in 
paragraph (I)(a)(2) of this appendix.
    (iv) The vehicle shall fail the idle mode and the test shall be 
terminated if none of the provisions of paragraphs (I)(c)(2)(i), (ii) 
and (iii) of this appendix is satisfied by an elapsed time of 90 seconds 
(mt=90). Alternatively, the vehicle may be failed if the provisions of 
paragraphs (I)(c)(2)(i) and (ii) of this appendix are not met within an 
elapsed time of 30 seconds.
    (v) Optional. The vehicle may fail the first-chance test and the 
second-chance test shall be omitted if no exhaust gas concentration 
lower than 1800 ppm HC is found by an elapsed time of 30 seconds 
(mt=30).
    (d) Second-chance test. If the vehicle fails the first-chance test, 
the test timer shall reset to zero (tt=0) and a second-chance test shall 
be performed. The second-chance test shall have an overall maximum test 
time of 425 seconds (tt=425). The test shall consist of a 
preconditioning mode followed immediately by an idle mode.
    (1) Preconditioning mode. The mode timer shall start (mt=0) when the 
engine speed is between 2200 and 2800 rpm. The mode shall continue for 
an elapsed time of 180 seconds (mt=180). If engine speed falls below 
2200 rpm or exceeds 2800 rmp for more than five seconds in any one 
excursion, or 15 seconds over all excursions, the mode timer shall reset 
to zero and resume timing.
    (2) Idle mode--(i) Ford Motor Company and Honda vehicles. The 
engines of 1981-1987 Ford Motor Company vehicles and 1984-1985 Honda 
Preludes shall be shut off for not more than 10 seconds and restarted. 
This procedure may also be used for 1988-1989 Ford Motor Company 
vehicles but should not be used for other vehicles. The probe may be 
removed from the tailpipe or the sample pump turned off if necessary to 
reduce analyzer fouling during the restart procedure.
    (ii) The mode timer shall start (mt=0) when the vehicle engine speed 
is between 350 and 1100 rpm. If engine speed exceeds 1100 rpm or falls 
below 350 rpm, the mode timer shall reset to zero and resume timing. The 
minimum idle mode length shall be determined as described in paragraph 
(I)(d)(2)(iii) of this appendix. The maximum idle mode length shall be 
90 seconds elapsed time (mt=90).
    (iii) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt=10). A pass or fail determination shall be made for the 
vehicle and the idle mode shall be terminated as follows:
    (A) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, prior to an elapsed time of 30 seconds 
(mt=30), measured values are less than or equal to 100 ppm HC and 0.5 
percent CO.
    (B) The vehicle shall pass the idle mode and the test shall be 
terminated at the end of an elapsed time of 30 seconds (mt=30), if prior 
to that time the criteria of paragraph (I)(d)(2)(iii)(A) of this 
appendix are not satisfied and the measured values are less than or 
equal to the applicable short test standards as described in paragraph 
(I)(a)(2) of this appendix.
    (C) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, at any point between an elapsed time of 30 
seconds (mt=30) and 90 seconds (mt=90), measured values are less than or 
equal to the applicable short test standards described in paragraph 
(I)(a)(2) of this appendix.
    (D) The vehicle shall fail the idle mode and the test shall be 
terminated if none of the provisions of paragraphs (I)(d)(2)(iii)(A), 
(d)(2)(iii)(B), and (d)(2)(iii)(C) of this appendix are satisfied by an 
elapsed time of 90 seconds (mt=90).

                        (II) Two Speed Idle Test

    (a) General requirements--(1) Exhaust gas sampling algorithm. The 
analysis of exhaust gas concentrations shall begin 10 seconds after the 
applicable test mode begins. Exhaust gas concentrations shall be 
analyzed at a rate of two times per second. The measured value for pass/
fail determinations shall be a simple running average of the 
measurements taken over five seconds.
    (2) Pass/fail determination. A pass or fail determination shall be 
made for each applicable test mode based on a comparison of the short 
test standards contained in appendix C to this subpart, and the measured 
value for HC and CO as described in paragraph (II)(a)(1) of this 
appendix. A vehicle shall pass the test mode if any pair of simultaneous 
values for HC and CO are below or equal to the applicable short test 
standards. A vehicle shall fail the test mode if the values for either 
HC or CO, or both, in all simultaneous pairs of values are above the 
applicable standards.
    (3) Void test conditions. The test shall immediately end and any 
exhaust gas measurements shall be voided if the measured concentration 
of CO plus CO2 falls below six percent or the vehicle's 
engine stalls at any time during the test sequence.
    (4) Multiple exhaust pipes. Exhaust gas concentrations from vehicle 
engines equipped with multiple exhaust pipes shall be sampled 
simultaneously.
    (5) The test shall be immediately terminated upon reaching the 
overall maximum test time.
    (b) Test sequence. (1) The test sequence shall consist of a first-
chance test and a second-chance test as follows:

[[Page 252]]

    (i) The first-chance test, as described under paragraph (II)(c) of 
this appendix, shall consist of an idle mode followed by a high-speed 
mode.
    (ii) The second-chance high-speed mode, as described under paragraph 
(II)(c) of this appendix, shall immediately follow the first-chance 
high-speed mode. It shall be performed only if the vehicle fails the 
first-chance test. The second-chance idle mode, as described under 
paragraph (II)(d) of this appendix, shall follow the second-chance high-
speed mode and be performed only if the vehicle fails the idle mode of 
the first-chance test.
    (2) The test sequence shall begin only after the following 
requirements are met:
    (i) The vehicle shall be tested in as-received condition with the 
transmission in neutral or park and all accessories turned off. The 
engine shall be at normal operating temperature (as indicated by a 
temperature gauge, temperature lamp, touch test on the radiator hose, or 
other visual observation for overheating).
    (ii) For all pre-1996 model year vehicles, a tachometer shall be 
attached to the vehicle in accordance with the analyzer manufacturer's 
instructions. For 1996 and newer model year vehicles the OBD data link 
connector will be used to monitor RPM. In the event that an OBD data 
link connector is not available or that an RPM signal is not available 
over the data link connector, a tachometer shall be used instead.
    (iii) The sample probe shall be inserted into the vehicle's tailpipe 
to a minimum depth of 10 inches. If the vehicle's exhaust system 
prevents insertion to this depth, a tailpipe extension shall be used.
    (iv) The measured concentration of CO plus CO2 shall be 
greater than or equal to six percent.
    (c) First-chance test and second-chance high-speed mode. The test 
timer shall start (tt=0) when the conditions specified in paragraph 
(b)(2) of this section are met. The first-chance test and second-chance 
high-speed mode shall have an overall maximum test time of 425 seconds 
(tt=425). The first-chance test shall consist of an idle mode followed 
immediately by a high-speed mode. This is followed immediately by an 
additional second-chance high-speed mode, if necessary.
    (1) First-chance idle mode. (i) The mode timer shall start (mt=0) 
when the vehicle engine speed is between 350 and 1100 rpm. If engine 
speed exceeds 1100 rpm or falls below 350 rpm, the mode timer shall 
reset to zero and resume timing. The minimum idle mode length shall be 
determined as described in paragraph (II)(c)(1)(ii) of this appendix. 
The maximum idle mode length shall be 90 seconds elapsed time (mt=90).
    (ii) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt=10). A pass or fail determination shall be made for the 
vehicle and the mode terminated as follows:
    (A) The vehicle shall pass the idle mode and the mode shall be 
immediately terminated if, prior to an elapsed time of 30 seconds 
(mt=30), measured values are less than or equal to 100 ppm HC and 0.5 
percent CO.
    (B) The vehicle shall pass the idle mode and the mode shall be 
terminated at the end of an elapsed time of 30 seconds (mt=30) if, prior 
to that time, the criteria of paragraph (II)(c)(1)(ii)(A) of this 
appendix are not satisfied, and the measured values are less than or 
equal to the applicable short test standards as described in paragraph 
(II)(a)(2) of this appendix.
    (C) The vehicle shall pass the idle mode and the mode shall be 
immediately terminated if, at any point between an elapsed time of 30 
seconds (mt=30) and 90 seconds (mt=90), the measured values are less 
than or equal to the applicable short test standards as described in 
paragraph (II)(a)(2) of this appendix.
    (D) The vehicle shall fail the idle mode and the mode shall be 
terminated if none of the provisions of paragraphs (II)(c)(1)(ii)(A), 
(B), and (C) of this appendix is satisfied by an elapsed time of 90 
seconds (mt=90). Alternatively, the vehicle may be failed if the 
provisions of paragraphs (II)(c)(2)(i) and (ii) of this appendix are not 
met within an elapsed time of 30 seconds.
    (E) Optional. The vehicle may fail the first-chance test and the 
second-chance test shall be omitted if no exhaust gas concentration less 
than 1800 ppm HC is found by an elapsed time of 30 seconds (mt=30).
    (2) First-chance and second-chance high-speed modes. This mode 
includes both the first-chance and second-chance high-speed modes, and 
follows immediately upon termination of the first-chance idle mode.
    (i) The mode timer shall reset (mt=0) when the vehicle engine speed 
is between 2200 and 2800 rpm. If engine speed falls below 2200 rpm or 
exceeds 2800 rpm for more than two seconds in one excursion, or more 
than six seconds over all excursions within 30 seconds of the final 
measured value used in the pass/fail determination, the measured value 
shall be invalidated and the mode continued. If any excursion lasts for 
more than ten seconds, the mode timer shall reset to zero (mt=0) and 
timing resumed. The minimum high-speed mode length shall be determined 
as described under paragraphs (II)(c)(2)(ii) and (iii) of this appendix. 
The maximum high-speed mode length shall be 180 seconds elapsed time 
(mt=180).
    (ii) Ford Motor Company and Honda vehicles. For 1981-1987 model year 
Ford Motor Company vehicles and 1984-1985 model year Honda Preludes, the 
pass/fail analysis shall begin after an elapsed time of 10 seconds 
(mt=10) using the following procedure. This procedure may also be used 
for 1988-1989 Ford

[[Page 253]]

Motor Company vehicles but should not be used for other vehicles.
    (A) A pass or fail determination, as described below, shall be used, 
for vehicles that passed the idle mode, to determine whether the high-
speed test should be terminated prior to or at the end of an elapsed 
time of 180 seconds (mt=180).
    (1) The vehicle shall pass the high-speed mode and the test shall be 
immediately terminated if, prior to an elapsed time of 30 seconds 
(mt=30), the measured values are less than or equal to 100 ppm HC and 
0.5 percent CO.
    (2) The vehicle shall pass the high-speed mode and the test shall be 
terminated at the end of an elapsed time of 30 seconds (mt=30) if, prior 
to that time, the criteria of paragraph (II)(c)(2)(ii)(A)(1) of this 
appendix are not satisfied, and the measured values are less than or 
equal to the applicable short test standards as described in paragraph 
(II)(a)(2) of this appendix.
    (3) The vehicle shall pass the high-speed mode and the test shall be 
immediately terminated if, at any point between an elapsed time of 30 
seconds (mt=30) and 180 seconds (mt=180), the measured values are less 
than or equal to the applicable short test standards as described in 
paragraph (II)(a)(2) of this appendix.
    (4) Restart. If at an elapsed time of 90 seconds (mt=90) the 
measured values are greater than the applicable short test standards as 
described in paragraph (II)(a)(2) of this appendix, the vehicle's engine 
shall be shut off for not more than 10 seconds after returning to idle 
and then shall be restarted. The probe may be removed from the tailpipe 
or the sample pump turned off if necessary to reduce analyzer fouling 
during the restart procedure. The mode timer will stop upon engine shut 
off (mt=90) and resume upon engine restart. The pass/fail determination 
shall resume as follows after 100 seconds have elapsed (mt=100).
    (i) The vehicle shall pass the high-speed mode and the test shall be 
immediately terminated if, at any point between an elapsed time of 100 
seconds (mt=100) and 180 seconds (mt=180), the measured values are less 
than or equal to the applicable short test standards described in 
paragraph (II)(a)(2) of this appendix.
    (ii) The vehicle shall fail the high-speed mode and the test shall 
be terminated if paragraph (II)(c)(2)(ii)(A)(4)(i) of this appendix is 
not satisfied by an elapsed time of 180 seconds (mt=180).
    (B) A pass or fail determination shall be made for vehicles that 
failed the idle mode and the high-speed mode terminated at the end of an 
elapsed time of 180 seconds (mt=180) as follows:
    (1) The vehicle shall pass the high-speed mode and the mode shall be 
terminated at an elapsed time of 180 seconds (mt=180) if any measured 
values of HC and CO exhaust gas concentrations during the high-speed 
mode are less than or equal to the applicable short test standards as 
described in paragraph (II)(a)(2) of this appendix.
    (2) Restart. If at an elapsed time of 90 seconds (mt=90) the 
measured values of HC and CO exhaust gas concentrations during the high-
speed mode are greater than the applicable short test standards as 
described in paragraph (II)(a)(2) of this appendix, the vehicle's engine 
shall be shut off for not more than 10 seconds after returning to idle 
and then shall be restarted. The probe may be removed from the tailpipe 
or the sample pump turned off if necessary to reduce analyzer fouling 
during the restart procedure. The mode timer will stop upon engine shut 
off (mt=90) and resume upon engine restart. The pass/fail determination 
shall resume as follows after 100 seconds have elapsed (mt=100).
    (i) The vehicle shall pass the high-speed mode and the mode shall be 
terminated at an elapsed time of 180 seconds (mt=180) if any measured 
values of HC and CO exhaust gas concentrations during the high-speed 
mode are less than or equal to the applicable short test standards as 
described in paragraph (II)(a)(2) of this appendix.
    (ii) The vehicle shall fail the high-speed mode and the test shall 
be terminated if paragraph (II)(c)(2)(ii)(B)(2)(i) of this appendix is 
not satisfied by an elapsed time of 180 seconds (mt=180).
    (iii) All other light-duty motor vehicles. The pass/fail analysis 
for vehicles not specified in paragraph (II)(c)(2)(ii) of this appendix 
shall begin after an elapsed time of 10 seconds (mt=10) using the 
following procedure.
    (A) A pass or fail determination, as described below, shall be used 
for vehicles that passed the idle mode, to determine whether the high-
speed mode should be terminated prior to or at the end of an elapsed 
time of 180 seconds (mt=180).
    (1) The vehicle shall pass the high-speed mode and the test shall be 
immediately terminated if, prior to an elapsed time of 30 seconds 
(mt=30), any measured values are less than or equal to 100 ppm HC and 
0.5 percent CO.
    (2) The vehicle shall pass the high-speed mode and the test shall be 
terminated at the end of an elapsed time of 30 seconds (mt=30) if, prior 
to that time, the criteria of paragraph (II)(c)(2)(iii)(A)(1) of this 
appendix are not satisfied, and the measured values are less than or 
equal to the applicable short test standards as described in paragraph 
(II)(a)(2) of this appendix.
    (3) The vehicle shall pass the high-speed mode and the test shall be 
immediately terminated if, at any point between an elapsed time of 30 
seconds (mt=30) and 180 seconds (mt=180), the measured values are less 
than

[[Page 254]]

or equal to the applicable short test standards as described in 
paragraph (II)(a)(2) of this appendix.
    (4) The vehicle shall fail the high-speed mode and the test shall be 
terminated if none of the provisions of paragraphs 
(II)(c)(2)(iii)(A)(1), (2), and (3) of this appendix is satisfied by an 
elapsed time of 180 seconds (mt=180).
    (B) A pass or fail determination shall be made for vehicles that 
failed the idle mode and the high-speed mode terminated at the end of an 
elapsed time of 180 seconds (mt=180) as follows:
    (1) The vehicle shall pass the high-speed mode and the mode shall be 
terminated at an elapsed time of 180 seconds (mt=180) if any measured 
values are less than or equal to the applicable short test standards as 
described in paragraph (II)(a)(2) of this appendix.
    (2) The vehicle shall fail the high-speed mode and the test shall be 
terminated if paragraph (II)(c)(2)(iii)(B)(1) of this appendix is not 
satisfied by an elapsed time of 180 seconds (mt=180).
    (d) Second-chance idle mode. If the vehicle fails the first-chance 
idle mode and passes the high-speed mode, the test timer shall reset to 
zero (tt=0) and a second-chance idle mode shall commence. The second-
chance idle mode shall have an overall maximum test time of 145 seconds 
(tt=145). The test shall consist of an idle mode only.
    (1) The engines of 1981-1987 Ford Motor Company vehicles and 1984-
1985 Honda Preludes shall be shut off for not more than 10 seconds and 
restarted. The probe may be removed from the tailpipe or the sample pump 
turned off if necessary to reduce analyzer fouling during the restart 
procedure. This procedure may also be used for 1988-1989 Ford Motor 
Company vehicles but should not be used for other vehicles.
    (2) The mode timer shall start (mt=0) when the vehicle engine speed 
is between 350 and 1100 rpm. If the engine speed exceeds 1100 rpm or 
falls below 350 rpm the mode timer shall reset to zero and resume 
timing. The minimum second-chance idle mode length shall be determined 
as described in paragraph (II)(d)(3) of this appendix. The maximum 
second-chance idle mode length shall be 90 seconds elapsed time (mt=90).
    (3) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt=10). A pass or fail determination shall be made for the 
vehicle and the second-chance idle mode shall be terminated as follows:
    (i) The vehicle shall pass the second-chance idle mode and the test 
shall be immediately terminated if, prior to an elapsed time of 30 
seconds (mt=30), any measured values are less than or equal to 100 ppm 
HC and 0.5 percent CO.
    (ii) The vehicle shall pass the second-chance idle mode and the test 
shall be terminated at the end of an elapsed time of 30 seconds (mt=30) 
if, prior to that time, the criteria of paragraph (II)(d)(3)(i) of this 
appendix are not satisfied, and the measured values are less than or 
equal to the applicable short test standards as described in paragraph 
(II)(a)(2) of this appendix.
    (iii) The vehicle shall pass the second-chance idle mode and the 
test shall be immediately terminated if, at any point between an elapsed 
time of 30 seconds (mt=30) and 90 seconds (mt=90), the measured values 
are less than or equal to the applicable short test standards as 
described in paragraph (II)(a)(2) of this appendix.
    (iv) The vehicle shall fail the second-chance idle mode and the test 
shall be terminated if none of the provisions of paragraph 
(II)(d)(3)(i), (ii), and (iii) of this appendix is satisfied by an 
elapsed time of 90 seconds (mt=90).

                            (III) Loaded Test

    (a) General requirements--(1) Exhaust gas sampling algorithm. The 
analysis of exhaust gas concentrations shall begin 10 seconds after the 
applicable test mode begins. Exhaust gas concentrations shall be 
analyzed at a minimum rate of two times per second. The measured value 
for pass/fail determinations shall be a simple running average of the 
measurements taken over five seconds.
    (2) Pass/fail determination. A pass or fail determination shall be 
made for each applicable test mode based on a comparison of the short 
test standards contained in appendix C to this subpart and the measured 
value for HC and CO as described in paragraph (III)(a)(1) of this 
appendix. A vehicle shall pass the test mode if any pair of simultaneous 
values for HC and CO are below or equal to the applicable short test 
standards. A vehicle shall fail the test mode if the values for either 
HC or CO, or both, in all simultaneous pairs of values are above the 
applicable standards.
    (3) Void test conditions. The test shall immediately end and any 
exhaust gas measurements shall be voided if the measured concentration 
of CO plus CO2 falls below six percent or the vehicle's 
engine stalls at any time during the test sequence.
    (4) Multiple exhaust pipes. Exhaust gas concentrations from vehicle 
engines equipped with multiple exhaust pipes shall be sampled 
simultaneously.
    (5) The test shall be immediately terminated upon reaching the 
overall maximum test time.
    (b) Test sequence. (1) The test sequence shall consist of a loaded 
mode using a chassis dynamometer followed immediately by an idle mode as 
described under paragraphs (III)(c)(1) and (2) of this appendix.
    (2) The test sequence shall begin only after the following 
requirements are met:
    (i) The dynamometer shall be warmed up, in stabilized operating 
condition, adjusted,

[[Page 255]]

and calibrated in accordance with the procedures of appendix A to this 
subpart. Prior to each test, variable-curve dynamometers shall be 
checked for proper setting of the road-load indicator or road-load 
controller.
    (ii) The vehicle shall be tested in as-received condition with all 
accessories turned off. The engine shall be at normal operating 
temperature (as indicated by a temperature gauge, temperature lamp, 
touch test on the radiator hose, or other visual observation for 
overheating).
    (iii) The vehicle shall be operated during each mode of the test 
with the gear selector in the following position:
    (A) In drive for automatic transmissions and in second (or third if 
more appropriate) for manual transmissions for the loaded mode;
    (B) In park or neutral for the idle mode.
    (iv) For all pre-1996 model year vehicles, a tachometer shall be 
attached to the vehicle in accordance with the analyzer manufacturer's 
instructions. For 1996 and newer model year vehicles the OBD data link 
connector will be used to monitor RPM. In the event that an OBD data 
link connector is not available or that an RPM signal is not available 
over the data link connector, a tachometer shall be used instead.
    (v) The sample probe shall be inserted into the vehicle's tailpipe 
to a minimum depth of 10 inches. If the vehicle's exhaust system 
prevents insertion to this depth, a tailpipe extension shall be used.
    (vi) The measured concentration of CO plus CO2 shall be 
greater than or equal to six percent.
    (c) Overall test procedure. The test timer shall start (tt=0) when 
the conditions specified in paragraph (III)(b)(2) of this appendix are 
met and the mode timer initiates as specified in paragraph (III)(c)(1) 
of this appendix. The test sequence shall have an overall maximum test 
time of 240 seconds (tt=240). The test shall be immediately terminated 
upon reaching the overall maximum test time.
    (1) Loaded mode--(i) Ford Motor Company and Honda vehicles. 
(Optional) The engines of 1981-1987 Ford Motor Company vehicles and 
1984-1985 Honda Preludes shall be shut off for not more than 10 seconds 
and restarted. This procedure may also be used for 1988-1989 Ford Motor 
Company vehicles but should not be used for other vehicles. The probe 
may be removed from the tailpipe or the sample pump turned off if 
necessary to reduce analyzer fouling during the restart procedure.
    (ii) The mode timer shall start (mt=0) when the dynamometer speed is 
within the limits specified for the vehicle engine size according to the 
following schedule. If the dynamometer speed falls outside the limits 
for more than five seconds in one excursion, or 15 seconds over all 
excursions, the mode timer shall reset to zero and resume timing. The 
minimum mode length shall be determined as described in paragraph 
(III)(c)(1)(iii)(A) of this appendix. The maximum mode length shall be 
90 seconds elapsed time (mt=90).

                        Dynamometer Test Schedule
------------------------------------------------------------------------
                                                               Normal
                                                Roll speed     loading
       Gasoline engine size (cylinders)            (mph)       (brake
                                                             horsepower)
------------------------------------------------------------------------
4 or less.....................................       22-25  2.8-4.1
5-6...........................................       29-32  6.8-8.4
7 or more.....................................       32-35  8.4-10.8
------------------------------------------------------------------------

    (iii) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt=10). A pass or fail determination shall be made for the 
vehicle and the mode shall be terminated as follows:
    (A) The vehicle shall pass the loaded mode and the mode shall be 
immediately terminated if, at any point between an elapsed time of 30 
seconds (mt=30) and 90 seconds (mt=90), measured values are less than or 
equal to the applicable short test standards described in paragraph 
(a)(2) of this section.
    (B) The vehicle shall fail the loaded mode and the mode shall be 
terminated if paragraph (III)(c)(1)(iii)(A) of this appendix is not 
satisfied by an elapsed time of 90 seconds (mt=90).
    (C) Optional. The vehicle may fail the loaded mode and any 
subsequent idle mode shall be omitted if no exhaust gas concentration 
less than 1800 ppm HC is found by an elapsed time of 30 seconds (mt=30).
    (2) Idle mode--(i) Ford Motor Company and Honda vehicles. (Optional) 
The engines of 1981-1987 Ford Motor Company vehicles and 1984-1985 Honda 
Preludes shall be shut off for not more than 10 seconds and restarted. 
This procedure may also be used for 1988-1989 Ford Motor Company 
vehicles but should not be used for other vehicles. The probe may be 
removed from the tailpipe or the sample pump turned off if necessary to 
reduce analyzer fouling during the restart procedure.
    (ii) The mode timer shall start (mt=0) when the dynamometer speed is 
zero and the vehicle engine speed is between 350 and 1100 rpm. If engine 
speed exceeds 1100 rpm or falls below 350 rpm, the mode timer shall 
reset to zero and resume timing. The minimum idle mode length shall be 
determined as described in paragraph (II)(c)(2)(ii) of this appendix. 
The maximum idle mode length shall be 90 seconds elapsed time (mt=90).
    (iii) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt=10). A pass or fail determination shall be made for the 
vehicle and the mode shall be terminated as follows:

[[Page 256]]

    (A) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, prior to an elapsed time of 30 seconds 
(mt=30), measured values are less than or equal to 100 ppm HC and 0.5 
percent CO.
    (B) The vehicle shall pass the idle mode and the test shall be 
terminated at the end of an elapsed time of 30 seconds (mt=30) if, prior 
to that time, the criteria of paragraph (III)(c)(2)(iii)(A) of this 
appendix are not satisfied, and the measured values are less than or 
equal to the applicable short test standards as described in paragraph 
(III)(a)(2) of this appendix.
    (C) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, at any point between an elapsed time of 30 
seconds (mt=30) and 90 seconds (mt=90), measured values are less than or 
equal to the applicable short test standards described in paragraph 
(III)(a)(2) of this appendix.
    (D) The vehicle shall fail the idle mode and the test shall be 
terminated if none of the provisions of paragraphs (III)(c)(2)(iii)(A), 
(c)(2)(iii)(B), and (c)(2)(iii)(C) of this appendix is satisfied by an 
elapsed time of 90 seconds (mt=90).

                      (IV) Preconditioned IDLE TEST

    (a) General requirements--(1) Exhaust gas sampling algorithm. The 
analysis of exhaust gas concentrations shall begin 10 seconds after the 
applicable test mode begins. Exhaust gas concentrations shall be 
analyzed at a minimum rate of two times per second. The measured value 
for pass/fail determinations shall be a simple running average of the 
measurements taken over five seconds.
    (2) Pass/fail determination. A pass or fail determination shall be 
made for each applicable test mode based on a comparison of the short 
test standards contained in appendix C to this subpart, and the measured 
value for HC and CO as described in paragraph (IV)(a)(1) of this 
appendix. A vehicle shall pass the test mode if any pair of simultaneous 
values for HC and CO are below or equal to the applicable short test 
standards. A vehicle shall fail the test mode if the values for either 
HC or CO, or both, in all simultaneous pairs of values are above the 
applicable standards.
    (3) Void test conditions. The test shall immediately end and any 
exhaust gas measurements shall be voided if the measured concentration 
of CO plus CO2 falls below six percent or the vehicle's 
engine stalls at any time during the test sequence.
    (4) Multiple exhaust pipes. Exhaust gas concentrations from vehicle 
engines equipped with multiple exhaust pipes shall be sampled 
simultaneously.
    (5) The test shall be immediately terminated upon reaching the 
overall maximum test time.
    (b) Test sequence. (1) The test sequence shall consist of a first-
chance test and a second-chance test as follows:
    (i) The first-chance test, as described under paragraph (IV)(c) of 
this appendix, shall consist of a preconditioning mode followed by an 
idle mode.
    (ii) The second-chance test, as described under paragraph (IV)(d) of 
this appendix, shall be performed only if the vehicle fails the first-
chance test.
    (2) The test sequence shall begin only after the following 
requirements are met:
    (i) The vehicle shall be tested in as-received condition with the 
transmission in neutral or park and all accessories turned off. The 
engine shall be at normal operating temperature (as indicated by a 
temperature gauge, temperature lamp, touch test on the radiator hose, or 
other visual observation for overheating).
    (ii) For all pre-1996 model year vehicles, a tachometer shall be 
attached to the vehicle in accordance with the analyzer manufacturer's 
instructions. For 1996 and newer model year vehicles the OBD data link 
connector will be used to monitor RPM. In the event that an OBD data 
link connector is not available or that an RPM signal is not available 
over the data link connector, a tachometer shall be used instead.
    (iii) The sample probe shall be inserted into the vehicle's tailpipe 
to a minimum depth of 10 inches. If the vehicle's exhaust system 
prevents insertion to this depth, a tailpipe extension shall be used.
    (iv) The measured concentration of CO plus CO2 shall be greater than 
or equal to six percent.
    (c) First-chance test. The test timer shall start (tt=0) when the 
conditions specified in paragraph (IV)(b)(2) of this appendix are met. 
The test shall have an overall maximum test time of 200 seconds 
(tt=200). The first-chance test shall consist of a preconditioning mode 
followed immediately by an idle mode.
    (1) Preconditioning mode. The mode timer shall start (mt=0) when the 
engine speed is between 2200 and 2800 rpm. The mode shall continue for 
an elapsed time of 30 seconds (mt=30). If engine speed falls below 2200 
rpm or exceeds 2800 rpm for more than five seconds in any one excursion, 
or 15 seconds over all excursions, the mode timer shall reset to zero 
and resume timing.
    (2) Idle mode. (i) The mode timer shall start (mt=0) when the 
vehicle engine speed is between 350 and 1100 rpm. If engine speed 
exceeds 1100 rpm or falls below 350 rpm, the mode timer shall reset to 
zero and resume timing. The minimum idle mode length shall be determined 
as described in paragraph (IV)(c)(2)(ii) of this appendix. The maximum 
idle mode length shall be 90 seconds elapsed time (mt=90).
    (ii) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt=10). A pass

[[Page 257]]

or fail determination shall be made for the vehicle and the mode shall 
be terminated as follows:
    (A) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, prior to an elapsed time of 30 seconds 
(mt=30), measured values are less than or equal to 100 ppm HC and 0.5 
percent CO.
    (B) The vehicle shall pass the idle mode and the test shall be 
terminated at the end of an elapsed time of 30 seconds (mt=30) if, prior 
to that time, the criteria of paragraph (IV)(c)(2)(ii)(A) of this 
appendix are not satisfied, and the measured values are less than or 
equal to the applicable short test standards as described in paragraph 
(IV)(a)(2) of this appendix.
    (C) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, at any point between an elapsed time of 30 
seconds (mt=30) and 90 seconds (mt=90), measured values are less than or 
equal to the applicable short test standards as described in paragraph 
(IV)(a)(2) of this section.
    (D) The vehicle shall fail the idle mode and the test shall be 
terminated if none of the provisions of paragraphs (IV)(c)(2)(ii)(A), 
(B), and (C) of this appendix is satisfied by an elapsed time of 90 
seconds (mt=90). Alternatively, the vehicle may be failed if the 
provisions of paragraphs (IV)(c)(2) (i) and (ii) of this appendix are 
not met within an elapsed time of 30 seconds.
    (E) Optional. The vehicle may fail the first-chance test and the 
second-chance test shall be omitted if no exhaust gas concentration less 
than 1800 ppm HC is found at an elapsed time of 30 seconds (mt=30).
    (d) Second-chance test. If the vehicle fails the first-chance test, 
the test timer shall reset to zero and a second-chance test shall be 
performed. The second-chance test shall have an overall maximum test 
time of 425 seconds. The test shall consist of a preconditioning mode 
followed immediately by an idle mode.
    (1) Preconditioning mode. The mode timer shall start (mt=0) when 
engine speed is between 2200 and 2800 rpm. The mode shall continue for 
an elapsed time of 180 seconds (mt=180). If the engine speed falls below 
2200 rpm or exceeds 2800 rpm for more than five seconds in any one 
excursion, or 15 seconds over all excursions, the mode timer shall reset 
to zero and resume timing.
    (2) Idle mode--(i) Ford Motor Company and Honda vehicles. The 
engines of 1981-1987 Ford Motor Company vehicles and 1984-1985 Honda 
Preludes shall be shut off for not more than 10 seconds and then shall 
be restarted. The probe may be removed from the tailpipe or the sample 
pump turned off if necessary to reduce analyzer fouling during the 
restart procedure. This procedure may also be used for 1988-1989 Ford 
Motor Company vehicles but should not be used for other vehicles.
    (ii) The mode timer shall start (mt=0) when the vehicle engine speed 
is between 350 and 1100 rpm. If the engine speed exceeds 1100 rpm or 
falls below 350 rpm, the mode timer shall reset to zero and resume 
timing. The minimum idle mode length shall be determined as described in 
paragraph (IV)(d)(2)(iii) of this appendix. The maximum idle mode length 
shall be 90 seconds elapsed time (mt=90).
    (iii) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt=10). A pass or fail determination shall be made for the 
vehicle and the mode shall be terminated as follows:
    (A) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, prior to an elapsed time of 30 seconds 
(mt=30), measured values are less than or equal to 100 ppm HC and 0.5 
percent CO.
    (B) The vehicle shall pass the idle mode and the test shall be 
terminated at the end of an elapsed time of 30 seconds (mt=30) if, prior 
to that time, the criteria of paragraph (IV)(d)(2)(iii)(A) of this 
appendix are not satisfied, and the measured values are less than or 
equal to the applicable short test standards as described in paragraph 
(IV)(a)(2) of this appendix.
    (C) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, at any point between an elapsed time of 30 
seconds (mt=30) and 90 seconds (mt=90), measured values are less than or 
equal to the applicable short test standards described in paragraph 
(IV)(a)(2) of this appendix.
    (D) The vehicle shall fail the idle mode and the test shall be 
terminated if none of the provisions of paragraphs (IV)(d)(2)(iii) (A), 
(B), and (C) of this appendix is satisfied by an elapsed time of 90 
seconds (mt=90).

                (V) Idle Test With Loaded Preconditioning

    (a) General requirements--(1) Exhaust gas sampling algorithm. The 
analysis of exhaust gas concentrations shall begin 10 seconds after the 
applicable test mode begins. Exhaust gas concentrations shall be 
analyzed at a minimum rate of two times per second. The measured value 
for pass/fail determinations shall be a simple running average of the 
measurements taken over five seconds.
    (2) Pass/fail determination. A pass or fail determination shall be 
made for each applicable test mode based on a comparison of the short 
test standards contained in appendix C to this subpart, and the measured 
value for HC and CO as described in paragraph (V)(a)(1) of this 
appendix. A vehicle shall pass the test mode if any pair of simultaneous 
values for HC and CO are below or equal to the applicable short test 
standards. A vehicle shall fail the test mode if the values for either 
HC or CO, or both, in all simultaneous pairs of values are above the 
applicable standards.

[[Page 258]]

    (3) Void test conditions. The test shall immediately end and any 
exhaust gas measurements shall be voided if the measured concentration 
of CO plus CO2 falls below six percent or the vehicle's 
engine stalls at any time during the test sequence.
    (4) Multiple exhaust pipes. Exhaust gas concentrations from vehicle 
engines equipped with multiple exhaust pipes shall be sampled 
simultaneously.
    (5) The test shall be immediately terminated upon reaching the 
overall maximum test time.
    (b) Test sequence. (1) The test sequence shall consist of a first-
chance test and a second-chance test as follows:
    (i) The first-chance test, as described under paragraph (V)(c) of 
this appendix, shall consist of an idle mode.
    (ii) The second-chance test as described under paragraph (V)(d) of 
this appendix shall be performed only if the vehicle fails the first-
chance test.
    (2) The test sequence shall begin only after the following 
requirements are met:
    (i) The dynamometer shall be warmed up, in stabilized operating 
condition, adjusted, and calibrated in accordance with the procedures of 
appendix A to this subpart. Prior to each test, variable-curve 
dynamometers shall be checked for proper setting of the road-load 
indicator or road-load controller.
    (ii) The vehicle shall be tested in as-received condition with all 
accessories turned off. The engine shall be at normal operating 
temperature (as indicated by a temperature gauge, temperature lamp, 
touch test on the radiator hose, or other visual observation for 
overheating).
    (iii) The vehicle shall be operated during each mode of the test 
with the gear selector in the following position:
    (A) In drive for automatic transmissions and in second (or third if 
more appropriate) for manual transmissions for the loaded 
preconditioning mode;
    (B) In park or neutral for the idle mode.
    (iv) For all pre-1996 model year vehicles, a tachometer shall be 
attached to the vehicle in accordance with the analyzer manufacturer's 
instructions. For 1996 and newer model year vehicles the OBD data link 
connector will be used to monitor RPM. In the event that an OBD data 
link connector is not available or that an RPM signal is not available 
over the data link connector, a tachometer shall be used instead.
    (v) The sample probe shall be inserted into the vehicle's tailpipe 
to a minimum depth of 10 inches. If the vehicle's exhaust system 
prevents insertion to this depth, a tailpipe extension shall be used.
    (vi) The measured concentration of CO plus CO2 shall be 
greater than or equal to six percent.
    (c) First-chance test. The test timer shall start (tt=0) when the 
conditions specified in paragraph (V)(b)(2) of this appendix are met. 
The test shall have an overall maximum test time of 155 seconds 
(tt=155). The first-chance test shall consist of an idle mode only.
    (1) The mode timer shall start (mt=0) when the vehicle engine speed 
is between 350 and 1100 rpm. If the engine speed exceeds 1100 rpm or 
falls below 350 rpm, the mode timer shall reset to zero and resume 
timing. The minimum mode length shall be determined as described in 
paragraph (V)(c)(2) of this appendix. The maximum mode length shall be 
90 seconds elapsed time (mt=90).
    (2) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt=10). A pass or fail determination shall be made for the 
vehicle and the mode shall be terminated as follows:
    (i) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, prior to an elapsed time of 30 seconds 
(mt=30), measured values are less than or equal to 100 ppm HC and 0.5 
percent CO.
    (ii) The vehicle shall pass the idle mode and the test shall be 
terminated at the end of an elapsed time of 30 seconds (mt=30) if, prior 
to that time, the criteria of paragraph (V)(c)(2)(i) of this appendix 
are not satisfied, and the measured values are less than or equal to the 
applicable short test standards as described in paragraph (V)(a)(2) of 
this appendix.
    (iii) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, at any point between an elapsed time of 30 
seconds (mt=30) and 90 seconds (mt=90), the measured values are less 
than or equal to the applicable short test standards as described in 
paragraph (V)(a)(2) of this appendix.
    (iv) The vehicle shall fail the idle mode and the test shall be 
terminated if none of the provisions of paragraphs (V)(c)(2)(i), (ii), 
and (iii) of this appendix is satisfied by an elapsed time of 90 seconds 
(mt=90). Alternatively, the vehicle may be failed if the provisions of 
paragraphs (V)(c)(2) (i) and (ii) of this appendix are not met within an 
elapsed time of 30 seconds.
    (v) Optional. The vehicle may fail the first-chance test and the 
second-chance test shall be omitted if no exhaust gas concentration less 
than 1800 ppm HC is found at an elapsed time of 30 seconds (mt=30).
    (d) Second-chance test. If the vehicle fails the first-chance test, 
the test timer shall reset to zero (tt=0) and a second-chance test shall 
be performed. The second-chance test shall have an overall maximum test 
time of 200 seconds (tt=200). The test shall consist of a 
preconditioning mode using a chassis dynamometer, followed immediately 
by an idle mode.
    (1) Preconditioning mode. The mode timer shall start (mt=0) when the 
dynamometer speed is within the limits specified for the vehicle engine 
size in accordance with the

[[Page 259]]

following schedule. The mode shall continue for a minimum elapsed time 
of 30 seconds (mt=30). If the dynamometer speed falls outside the limits 
for more than five seconds in one excursion, or 15 seconds over all 
excursions, the mode timer shall reset to zero and resume timing.

------------------------------------------------------------------------
                                                      Dynamometer test
                                                          schedule
                                                   ---------------------
         Gasoline engine size (cylinders)                       Normal
                                                      Roll     loading
                                                     speed      (brake
                                                     (mph)   horsepower)
------------------------------------------------------------------------
4 or less.........................................    22-25  2.8-4.1
5-6...............................................    29-32  6.8-8.4
7 or more.........................................    32-35  8.4-10.8
------------------------------------------------------------------------

    (2) Idle mode. (i) Ford Motor Company and Honda vehicles. (Optional) 
The engines of 1981-1987 Ford Motor Company vehicles and 1984-1985 Honda 
Preludes shall be shut off for not more than 10 seconds and restarted. 
This procedure may also be used for 1988-1989 Ford Motor Company 
vehicles but should not be used for other vehicles. The probe may be 
removed from the tailpipe or the sample pump turned off if necessary to 
reduce analyzer fouling during the restart procedure.
    (ii) The mode timer shall start (mt=0) when the dynamometer speed is 
zero and the vehicle engine speed is between 350 and 1100 rpm. If the 
engine speed exceeds 1100 rpm or falls below 350 rpm, the mode timer 
shall reset to zero and resume timing. The minimum idle mode length 
shall be determined as described in paragraph (V)(d)(2)(ii) of this 
appendix. The maximum idle mode length shall be 90 seconds elapsed time 
(mt=90).
    (iii) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt=10). A pass or fail determination shall be made for the 
vehicle and the mode shall be terminated as follows:
    (A) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, prior to an elapsed time of 30 seconds 
(mt=30), measured values are less than or equal to 100 ppm HC and 0.5 
percent CO.
    (B) The vehicle shall pass the idle mode and the test shall be 
terminated at the end of an elapsed time of 30 seconds (mt=30) if, prior 
to that time, the criteria of paragraph (V)(d)(2)(ii)(A) of this 
appendix are not satisfied, and the measured values are less than or 
equal to the applicable short test standards as described in paragraph 
(V)(a)(2) of this appendix.
    (C) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, at any point between an elapsed time of 30 
seconds (mt=30) and 90 seconds (mt=90), the measured values are less 
than or equal to the applicable short test standards as described in 
paragraph (V)(a)(2) of this appendix.
    (D) The vehicle shall fail the idle mode and the test shall be 
terminated if none of the provisions of paragraphs (V)(d)(2)(ii)(A), 
(B), and (C) of this appendix is satisfied by an elapsed time of 90 
seconds (mt=90).

                 (VI) Preconditioned Two Speed Idle Test

    (a) General requirements--(1) Exhaust gas sampling algorithm. The 
analysis of exhaust gas concentrations shall begin 10 seconds after the 
applicable test mode begins. Exhaust gas concentrations shall be 
analyzed at a minimum rate of two times per second. The measured value 
for pass/fail determinations shall be a simple running average of the 
measurements taken over five seconds.
    (2) Pass/fail determination. A pass or fail determination shall be 
made for each applicable test mode based on a comparison of the short 
test standards contained in appendix C to this subpart, and the measured 
value for HC and CO as described in paragraph (VI)(a)(1) of this 
appendix. A vehicle shall pass the test mode if any pair of simultaneous 
values for HC and CO are below or equal to the applicable short test 
standards. A vehicle shall fail the test mode if the values for either 
HC or CO, or both, in all simultaneous pairs of values are above the 
applicable standards.
    (3) Void test conditions. The test shall immediately end and any 
exhaust gas measurements shall be voided if the measured concentration 
of CO plus CO2 falls below six percent or the vehicle's 
engine stalls at any time during the test sequence.
    (4) Multiple exhaust pipes. Exhaust gas concentrations from vehicle 
engines equipped with multiple exhaust pipes shall be sampled 
simultaneously.
    (5) The test shall be immediately terminated upon reaching the 
overall maximum test time.
    (b) Test sequence. (1) The test sequence shall consist of a first-
chance test and a second-chance test as follows:
    (i) The first-chance test, as described under paragraph (VI)(c) of 
this appendix, shall consist of a first-chance high-speed mode followed 
immediately by a first-chance idle mode.
    (ii) The second-chance test as described under paragraph (VI)(d) of 
this appendix shall be performed only if the vehicle fails the first-
chance test.
    (2) The test sequence shall begin only after the following 
requirements are met:
    (i) The vehicle shall be tested in as-received condition with the 
transmission in neutral or park and all accessories turned off. The 
engine shall be at normal operating temperature (as indicated by a 
temperature gauge, temperature lamp, touch test on the radiator hose, or 
other visual observation for overheating).
    (ii) For all pre-1996 model year vehicles, a tachometer shall be 
attached to the vehicle

[[Page 260]]

in accordance with the analyzer manufacturer's instructions. For 1996 
and newer model year vehicles the OBD data link connector will be used 
to monitor rpm. In the event that an OBD data link connector is not 
available or that an rpm signal is not available over the data link 
connector, a tachometer shall be used instead.
    (iii) The sample probe shall be inserted into the vehicle's tailpipe 
to a minimum depth of 10 inches. If the vehicle's exhaust system 
prevents insertion to this depth, a tailpipe extension shall be used.
    (iv) The measured concentration of CO plus CO2 shall be 
greater than or equal to six percent.
    (c) First-chance test. The test timer shall start (tt=0) when the 
conditions specified in paragraph (VI)(b)(2) of this appendix are met. 
The test shall have an overall maximum test time of 290 seconds 
(tt=290). The first-chance test shall consist of a high-speed mode 
followed immediately by an idle mode.
    (1) First-chance high-speed mode. (i) The mode timer shall reset 
(mt=0) when the vehicle engine speed is between 2200 and 2800 rpm. If 
the engine speed falls below 2200 rpm or exceeds 2800 rpm for more than 
two seconds in one excursion, or more than six seconds over all 
excursions within 30 seconds of the final measured value used in the 
pass/fail determination, the measured value shall be invalidated and the 
mode continued. If any excursion lasts for more than ten seconds, the 
mode timer shall reset to zero (mt=0) and timing resumed. The high-speed 
mode length shall be 90 seconds elapsed time (mt=90).
    (ii) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt=10). A pass or fail determination shall be made for the 
vehicle and the mode shall be terminated as follows:
    (A) The vehicle shall pass the high-speed mode and the mode shall be 
terminated at an elapsed time of 90 seconds (mt=90) if any measured 
values are less than or equal to the applicable short test standards as 
described in paragraph (VI)(a)(2) of this appendix.
    (B) The vehicle shall fail the high-speed mode and the mode shall be 
terminated if the requirements of paragraph (VI)(c)(1)(ii)(A) of this 
appendix are not satisfied by an elapsed time of 90 seconds (mt=90).
    (C) Optional. The vehicle shall fail the first-chance test and any 
subsequent test shall be omitted if no exhaust gas concentration lower 
than 1800 ppm HC is found at an elapsed time of 30 seconds (mt=30).
    (2) First-chance idle mode. (i) The mode timer shall start (mt=0) 
when the vehicle engine speed is between 350 and 1100 rpm. If the engine 
speed exceeds 1100 rpm or falls below 350 rpm, the mode timer shall 
reset to zero and resume timing. The minimum first-chance idle mode 
length shall be determined as described in paragraph (VI)(c)(2)(ii) of 
this appendix. The maximum first-chance idle mode length shall be 90 
seconds elapsed time (mt=90).
    (ii) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt=10). A pass or fail determination shall be made for the 
vehicle and the mode shall be terminated as follows:
    (A) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, prior to an elapsed time of 30 seconds 
(mt=30), measured values are less than or equal to 100 ppm HC and 0.5 
percent CO.
    (B) The vehicle shall pass the idle mode and the test shall be 
terminated at the end of an elapsed time of 30 seconds (mt=30) if, prior 
to that time, the criteria of paragraph (VI)(c)(2)(ii)(A) of this 
appendix are not satisfied, and the measured values are less than or 
equal to the applicable short test standards as described in paragraph 
(VI)(a)(2) of this appendix.
    (C) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, at any point between an elapsed time of 30 
seconds (mt=30) and 90 seconds (mt=90), the measured values are less 
than or equal to the applicable short test standards as described in 
paragraph (VI)(a)(2) of this appendix.
    (D) The vehicle shall fail the idle mode and the test shall be 
terminated if none of the provisions of paragraphs (VI)(c)(2)(ii) (A), 
(B), and (C) of this appendix is satisfied by an elapsed time of 90 
seconds (mt=90). Alternatively, the vehicle may be failed if the 
provisions of paragraphs (VI)(c)(2)(i) and (ii) of this appendix are not 
met within the elapsed time of 30 seconds.
    (d) Second-chance test. (1) If the vehicle fails either mode of the 
first-chance test, the test timer shall reset to zero (tt=0) and a 
second-chance test shall commence. The second-chance test shall be 
performed based on the first-chance test failure mode or modes as 
follows:
    (A) If the vehicle failed only the first-chance high-speed mode, the 
second-chance test shall consist of a second-chance high-speed mode as 
described in paragraph (VI)(d)(2) of this appendix. The overall maximum 
test time shall be 280 seconds (tt=280).
    (B) If the vehicle failed only the first-chance idle mode, the 
second-chance test shall consist of a second-chance pre-conditioning 
mode followed immediately by a second-chance idle mode as described in 
paragraphs (VI)(d) (3) and (4) of this appendix. The overall maximum 
test time shall be 425 seconds (tt=425).
    (C) If both the first-chance high-speed mode and first-chance idle 
mode were failed, the second-chance test shall consist of the second-
chance high-speed mode followed immediately by the second-chance idle 
mode as described in paragraphs (VI)(d) (2) and (4) of

[[Page 261]]

this appendix. However, if during this second-chance procedure the 
vehicle fails the second-chance high-speed mode, then the second-chance 
idle mode may be eliminated. The overall maximum test time shall be 425 
seconds (tt=425).
    (2) Second-chance high-speed mode--(i) Ford Motor Company and Honda 
vehicles. The engines of 1981-1987 Ford Motor Company vehicles and 1984-
1985 Honda Preludes shall be shut off for not more than 10 seconds and 
then shall be restarted. The probe may be removed from the tailpipe or 
the sample pump turned off if necessary to reduce analyzer fouling 
during the restart procedure. This procedure may also be used for 1988-
1989 Ford Motor Company vehicles but should not be used for other 
vehicles.
    (ii) The mode timer shall reset (mt=0) when the vehicle engine speed 
is between 2200 and 2800 rpm. If the engine speed falls below 2200 rpm 
or exceeds 2800 rpm for more than two seconds in one excursion, or more 
than six seconds over all excursions within 30 seconds of the final 
measured value used in the pass/fail determination, the measured value 
shall be invalidated and the mode continued. The minimum second-chance 
high-speed mode length shall be determined as described in paragraphs 
(VI)(d)(2) (iii) and (iv) of this appendix. If any excursion lasts for 
more than ten seconds, the mode timer shall reset to zero (mt=0) and 
timing resumed. The maximum second-chance high-speed mode length shall 
be 180 seconds elapsed time (mt=180).
    (iii) In the case where the second-chance high-speed mode is not 
followed by the second-chance idle mode, the pass/fail analysis shall 
begin after an elapsed time of 10 seconds (mt=10). A pass or fail 
determination shall be made for the vehicle and the mode shall be 
terminated as follows:
    (A) The vehicle shall pass the high-speed mode and the test shall be 
immediately terminated if, prior to an elapsed time of 30 seconds 
(mt=30), measured values are less than or equal to 100 ppm HC and 0.5 
percent CO.
    (B) The vehicle shall pass the high-speed mode and the test shall be 
terminated if at the end of an elapsed time of 30 seconds (mt=30) if, 
prior to that time, the criteria of paragraph (VI)(d)(2)(iii)(A) of this 
appendix are not satisfied, and the measured values are less than or 
equal to the applicable short test standards as described in paragraph 
(VI)(a)(2) of this appendix.
    (C) The vehicle shall pass the high-speed mode and the test shall be 
immediately terminated if, at any point between an elapsed time for 30 
seconds (mt=30) and 180 seconds (mt=180), the measured values are less 
than or equal to the applicable short test standards as described in 
paragraph (VI)(a)(2) of this appendix.
    (D) The vehicle shall fail the high-speed mode and the test shall be 
terminated if none of the provisions of paragraphs (VI)(d)(2)(iii) (A), 
(B), and (C) of this appendix is satisfied by an elapsed time of 180 
seconds (mt=180).
    (iv) In the case where the second-chance high-speed mode is followed 
by the second-chance idle mode, the pass/fail analysis shall begin after 
an elapsed time of 10 seconds (mt=10). A pass or fail determination 
shall be made for the vehicle and the mode shall be terminated as 
follows:
    (A) The vehicle shall pass the high-speed mode and the mode shall be 
terminated at the end of an elapsed time of 180 seconds (mt=180) if any 
measured values are less than or equal to the applicable short test 
standards as described in paragraph (VI)(a)(2) of this appendix.
    (B) The vehicle shall fail the high-speed mode and the mode shall be 
terminated if paragraph (VI)(d)(2)(iv)(A) of this appendix is not 
satisfied by an elapsed time of 180 seconds (mt=180).
    (3) Second-chance preconditioning mode. The mode timer shall start 
(mt=0) when engine speed is between 2200 and 2800 rpm. The mode shall 
continue for an elapsed time of 180 seconds (mt=180). If the engine 
speed falls below 2200 rpm or exceeds 2800 rpm for more than five 
seconds in any one excursion, or 15 seconds over all excursions, the 
mode timer shall reset to zero and resume timing.
    (4) Second-chance idle mode--(i) Ford Motor Company and Honda 
vehicles. The engines of 1981-1987 Ford Motor Company vehicles and 1984-
1985 Honda Preludes shall be shut off for not more than 10 seconds and 
then shall be restarted. The probe may be removed from the tailpipe or 
the sample pump turned off if necessary to reduce analyzer fouling 
during the restart procedure. This procedure may also be used for 1988-
1989 Ford Motor Company vehicles but should not be used for other 
vehicles.
    (ii) The mode timer shall start (mt=0) when the vehicle engine speed 
is between 350 and 1100 rpm. If the engine exceeds 1100 rpm or falls 
below 350 rpm the mode timer shall reset to zero and resume timing. The 
minimum second-chance idle mode length shall be determined as described 
in paragraph (VI)(d)(4)(iii) of this appendix. The maximum second-chance 
idle mode length shall be 90 seconds elapsed time (mt=90).
    (iii) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt=10). A pass or fail determination shall be made for the 
vehicle and the mode shall be terminated as follows:
    (A) The vehicle shall pass the second-chance idle mode and the test 
shall be immediately terminated if, prior to an elapsed time of 30 
seconds (mt=30), measured values are less than or equal to 100 ppm HC 
and 0.5 percent CO.

[[Page 262]]

    (B) The vehicle shall pass the second-chance idle mode and the test 
shall be terminated at the end of an elapsed time of 30 seconds (mt=30) 
if, prior to that time, the criteria of paragraph (VI)(d)(4)(iii)(A) of 
this appendix are not satisfied, and the measured values are less than 
or equal to the applicable short test standards as described in 
paragraph (VI)(a)(2) of this appendix.
    (C) The vehicle shall pass the second-chance idle mode and the test 
shall be immediately terminated if, at any point between an elapsed time 
of 30 seconds (mt=30) and 90 seconds (mt=90), measured values are less 
than or equal to the applicable short test standards described in 
paragraph (VI)(a)(2) of this appendix.
    (D) The vehicle shall fail the second-chance idle mode and the test 
shall be terminated if none of the provisions of paragraphs 
(VI)(d)(4)(iii) (A), (B), and (C) of this appendix is satisfied by an 
elapsed time of 90 seconds (mt=90).

[ 57 FR 52987, Nov. 5, 1992, as amended at 61 FR 40946, Aug. 6, 1996]

       Appendix C to Subpart S--Steady-State Short Test Standards

   (I) Short Test Standards for 1981 and Later Model Year Light-Duty 
                                Vehicles

    For 1981 and later model year light-duty vehicles for which any of 
the test procedures described in appendix B to this subpart are utilized 
to establish Emissions Performance Warranty eligibility (i.e., 1981 and 
later model year light-duty vehicles at low altitude and 1982 and later 
model year vehicles at high altitude to which high altitude 
certification standards of 1.5 gpm HC and 15 gpm CO or less apply), 
short test emissions for all tests and test modes shall not exceed:
    (a) Hydrocarbons: 220 ppm as hexane.
    (b) Carbon monoxide: 1.2%.

   (II) Short Test Standards for 1981 and Later Model Year Light-Duty 
                                 Trucks

    For 1981 and later model year light-duty trucks for which any of the 
test procedures described in appendix B to this subpart are utilized to 
establish Emissions Performance Warranty eligibility (i.e., 1981 and 
later model year light-duty trucks at low altitude and 1982 and later 
model year trucks at high altitude to which high altitude certification 
standards of 2.0 gpm HC and 26 gpm CO or less apply), short test 
emissions for all tests and test modes shall not exceed:
    (a) Hydrocarbons: 220 ppm as hexane.
    (b) Carbon monoxide: 1.2%.

       Appendix D to Subpart S--Steady-State Short Test Equipment

              (I) Steady-State Test Exhaust Analysis System

    (a) Sampling system--(1) General requirements. The sampling system 
for steady-state short tests shall, at a minimum, consist of a tailpipe 
probe, a flexible sample line, a water removal system, particulate trap, 
sample pump, flow control components, tachometer or dynamometer, 
analyzers for HC, CO, and CO2, and digital displays for 
exhaust concentrations of HC, CO, and CO2, and engine rpm. 
Materials that are in contact with the gases sampled shall not 
contaminate or change the character of the gases to be analyzed, 
including gases from alcohol fueled vehicles. The probe shall be capable 
of being inserted to a depth of at least ten inches into the tailpipe of 
the vehicle being tested, or into an extension boot if one is used. A 
digital display for dynamometer speed and load shall be included if the 
test procedures described in appendix B to this subpart, paragraphs 
(III) and (V), are conducted. Minimum specifications for optional NO 
analyzers are also described in this appendix. The analyzer system shall 
be able to test, as specified in at least one section in appendix B to 
this subpart, all model vehicles in service at the time of sale of the 
analyzer.
    (2) Temperature operating range. The sampling system and all 
associated hardware shall be of a design certified to operate within the 
performance specifications described in paragraph (I)(b) of this 
appendix in ambient air temperatures ranging from 41 to 110 degrees 
Fahrenheit. The analyzer system shall, where necessary, include features 
to keep the sampling system within the specified range.
    (3) Humidity operating range. The sampling system and all associated 
hardware shall be of a design certified to operate within the 
performance specifications described in paragraph (I)(b) of this 
appendix at a minimum of 80 percent relative humidity throughout the 
required temperature range.
    (4) Barometric pressure compensation. Barometric pressure 
compensation shall be provided. Compensation shall be made for 
elevations up to 6,000 feet (above mean sea level). At any given 
altitude and ambient conditions specified in paragraph (I)(b) of this 
appendix, errors due to barometric pressure changes of 2 
inches of mercury shall not exceed the accuracy limits specified in 
paragraph (I)(b) of this appendix.
    (5) Dual sample probe requirements. When testing a vehicle with dual 
exhaust pipes, a dual sample probe of a design certified by the analyzer 
manufacturer to provide equal flow in each leg shall be used. The equal 
flow requirement is considered to be met if the flow

[[Page 263]]

rate in each leg of the probe has been measured under two sample pump 
flow rates (the normal rate and a rate equal to the onset of low flow), 
and if the flow rates in each of the legs are found to be equal to each 
other (within 15% of the flow rate in the leg having lower flow).
    (6) System lockout during warm-up. Functional operation of the gas 
sampling unit shall remain disabled through a system lockout until the 
instrument meets stability and warm-up requirements. The instrument 
shall be considered ``warmed up'' when the zero and span readings for 
HC, CO, and CO2 have stabilized, within 3% of the 
full range of low scale, for five minutes without adjustment.
    (7) Electromagnetic isolation and interference. Electromagnetic 
signals found in an automotive service environment shall not cause 
malfunctions or changes in the accuracy in the electronics of the 
analyzer system. The instrument design shall ensure that readings do not 
vary as a result of electromagnetic radiation and induction devices 
normally found in the automotive service environment, including high 
energy vehicle ignition systems, radio frequency transmission radiation 
sources, and building electrical systems.
    (8) Vibration and shock protection. System operation shall be 
unaffected by the vibration and shock encountered under the normal 
operating conditions encountered in an automotive service environment.
    (9) Propane equivalency factor. The propane equivalency factor shall 
be displayed in a manner that enables it to be viewed conveniently, 
while permitting it to be altered only by personnel specifically 
authorized to do so.
    (b) Analyzers--(1) Accuracy. The analyzers shall be of a design 
certified to meet the following accuracy requirements when calibrated to 
the span points specified in appendix A to this subpart:

------------------------------------------------------------------------
           Channel               Range    Accuracy  Noise  Repeatability
------------------------------------------------------------------------
HC, ppm.....................  0-400       2, %......................  0-4.0       2.................................  0.1% CO2.
NO..................................  1ppm NO.
RPM.................................  1rpm.
 

    (3) Response time. The response time from the probe to the display 
for HC, CO, and CO2 analyzers shall not exceed eight seconds 
to 90% of a step change in input. For NO analyzers, the response time 
shall not exceed twelve seconds to 90% of a step change in input.
    (4) Display refresh rate. Dynamic information being displayed shall 
be refreshed at a minimum rate of twice per second.
    (5) Interference effects. The interference effects for non-interest 
gases shall not exceed 10 ppm for hydrocarbons, 
0.05 percent for carbon monoxide, 0.20 percent 
for carbon dioxide, and 20 ppm for oxides of nitrogen.
    (6) Low flow indication. The analyzer shall provide an indication 
when the sample flow is below the acceptable level. The sampling system 
shall be equipped with a flow meter (or equivalent) that shall indicate 
sample flow degradation when meter error exceeds three percent of full 
scale, or causes system response time to exceed 13 seconds to 90 percent 
of a step change in input, whichever is less.
    (7) Engine speed detection. The analyzer shall utilize a tachometer 
capable of detecting engine speed in revolutions per minute (rpm) with a 
0.5 second response time and an accuracy of 3% of the true 
rpm.
    (8) Test and mode timers. The analyzer shall be capable of 
simultaneously determining the amount of time elapsed in a test, and in 
a mode within that test.
    (9) Sample rate. The analyzer shall be capable of measuring exhaust 
concentrations of gases specified in this section at a minimum rate of 
twice per second.
    (c) Demonstration of conformity. The analyzer shall be demonstrated 
to the satisfaction of the inspection program manager, through 
acceptance testing procedures, to meet the requirements of this section 
and that it is capable of being maintained as required in appendix A to 
this subpart.

                   (II) Steady-State Test Dynamometer

    (a) The chassis dynamometer for steady-state short tests shall 
provide the following capabilities:
    (1) Power absorption. The dynamometer shall be capable of applying a 
load to the vehicle's driving tire surfaces at the horsepower and speed 
levels specified in paragraph (II)(b) of this appendix.
    (2) Short-term stability. Power absorption at constant speed shall 
not drift more than 0.5 horsepower (hp) during any single 
test mode.
    (3) Roll weight capacity. The dynamometer shall be capable of 
supporting a driving axle weight up to four thousand (4,000) pounds or 
greater.
    (4) Between roll wheel lifts. These shall be controllable and 
capable of lifting a minimum of four thousand (4,000) pounds.
    (5) Roll brakes. Both rolls shall be locked when the wheel lift is 
up.

[[Page 264]]

    (6) Speed indications. The dynamometer speed display shall have a 
range of 0-60 mph, and a resolution and accuracy of at least 1 mph.
    (7) Safety interlock. A roll speed sensor and safety interlock 
circuit shall be provided which prevents the application of the roll 
brakes and upward lift movement at any roll speed above 0.5 mph.
    (b) The dynamometer shall produce the load speed relationships 
specified in paragraphs (III) and (V) of appendix B to this subpart.

           (III) Transient Emission Test Equipment [Reserved]

         (IV) Evaporative System Purge Test Equipment [Reserved]

       (V) Evaporative System Integrity Test Equipment [Reserved]

[57 FR 52987, Nov. 5, 1992, as amended at 58 FR 59367, Nov. 9, 1993]

          Appendix E to Subpart S--Transient Test Driving Cycle

    (I) Driver's trace. All excursions in the transient driving cycle 
shall be evaluated by the procedures defined in Sec. 86.115-78(b)(1) and 
Sec. 86.115(c) of this chapter. Excursions exceeding these limits shall 
cause a test to be void. In addition, provisions shall be available to 
utilize cycle validation criteria, as described in Sec. 86.1341-90 of 
this chapter, for trace speed versus actual speed as a means to 
determine a valid test.
    (II) Driving cycle. The following table shows the time speed 
relationship for the transient IM240 test procedure.

------------------------------------------------------------------------
                             Second                                MPH
------------------------------------------------------------------------
0..............................................................     0
1..............................................................     0
2..............................................................     0
3..............................................................     0
4..............................................................     0
5..............................................................     3
6..............................................................     5.9
7..............................................................     8.6
8..............................................................    11.5
9..............................................................    14.3
10.............................................................    16.9
11.............................................................    17.3
12.............................................................    18.1
13.............................................................    20.7
14.............................................................    21.7
15.............................................................    22.4
16.............................................................    22.5
17.............................................................    22.1
18.............................................................    21.5
19.............................................................    20.9
20.............................................................    20.4
21.............................................................    19.8
22.............................................................    17
23.............................................................    14.9
24.............................................................    14.9
25.............................................................    15.2
26.............................................................    15.5
27.............................................................    16
28.............................................................    17.1
29.............................................................    19.1
30.............................................................    21.1
31.............................................................    22.7
32.............................................................    22.9
33.............................................................    22.7
34.............................................................    22.6
35.............................................................    21.3
36.............................................................    19
37.............................................................    17.1
38.............................................................    15.8
39.............................................................    15.8
40.............................................................    17.7
41.............................................................    19.8
42.............................................................    21.6
43.............................................................    23.2
44.............................................................    24.2
45.............................................................    24.6
46.............................................................    24.9
47.............................................................    25
48.............................................................    25.7
49.............................................................    26.1
50.............................................................    26.7
51.............................................................    27.5
52.............................................................    28.6
53.............................................................    29.3
54.............................................................    29.8
55.............................................................    30.1
56.............................................................    30.4
57.............................................................    30.7
58.............................................................    30.7
59.............................................................    30.5
60.............................................................    30.4
61.............................................................    30.3
62.............................................................    30.4
63.............................................................    30.8
64.............................................................    30.4
65.............................................................    29.9
66.............................................................    29.5
67.............................................................    29.8
68.............................................................    30.3
69.............................................................    30.7
70.............................................................    30.9
71.............................................................    31
72.............................................................    30.9
73.............................................................    30.4
74.............................................................    29.8
75.............................................................    29.9
76.............................................................    30.2
77.............................................................    30.7
78.............................................................    31.2
79.............................................................    31.8
80.............................................................    32.2
81.............................................................    32.4
82.............................................................    32.2
83.............................................................    31.7
84.............................................................    28.6
85.............................................................    25.1
86.............................................................    21.6
87.............................................................    18.1
88.............................................................    14.6
89.............................................................    11.1
90.............................................................     7.6
91.............................................................     4.1
92.............................................................     0.6
93.............................................................     0
94.............................................................     0
95.............................................................     0
96.............................................................     0
97.............................................................     0
98.............................................................     3.3
99.............................................................     6.6

[[Page 265]]

 
100............................................................     9.9
101............................................................    13.2
102............................................................    16.5
103............................................................    19.8
104............................................................    22.2
105............................................................    24.3
106............................................................    25.8
107............................................................    26.4
108............................................................    25.7
109............................................................    25.1
110............................................................    24.7
111............................................................    25.2
112............................................................    25.4
113............................................................    27.2
114............................................................    26.5
115............................................................    24
116............................................................    22.7
117............................................................    19.4
118............................................................    17.7
119............................................................    17.2
120............................................................    18.1
121............................................................    18.6
122............................................................    20
123............................................................    20.7
124............................................................    21.7
125............................................................    22.4
126............................................................    22.5
127............................................................    22.1
128............................................................    21.5
129............................................................    20.9
130............................................................    20.4
131............................................................    19.8
132............................................................    17
133............................................................    17.1
134............................................................    15.8
135............................................................    15.8
136............................................................    17.7
137............................................................    19.8
138............................................................    21.6
139............................................................    22.2
140............................................................    24.5
141............................................................    24.7
142............................................................    24.8
143............................................................    24.7
144............................................................    24.6
145............................................................    24.6
146............................................................    25.1
147............................................................    25.6
148............................................................    25.7
149............................................................    25.4
150............................................................    24.9
151............................................................    25
152............................................................    25.4
153............................................................    26
154............................................................    26
155............................................................    25.7
156............................................................    26.1
157............................................................    26.7
158............................................................    27.3
159............................................................    30.5
160............................................................    33.5
161............................................................    36.2
162............................................................    37.3
163............................................................    39.3
164............................................................    40.5
165............................................................    42.1
166............................................................    43.5
167............................................................    45.1
168............................................................    46
169............................................................    46.8
170............................................................    47.5
171............................................................    47.5
172............................................................    47.3
173............................................................    47.2
174............................................................    47.2
175............................................................    47.4
176............................................................    47.9
177............................................................    48.5
178............................................................    49.1
179............................................................    49.5
180............................................................    50
181............................................................    50.6
182............................................................    51
183............................................................    51.5
184............................................................    52.2
185............................................................    53.2
186............................................................    54.1
187............................................................    54.6
188............................................................    54.9
189............................................................    55
190............................................................    54.9
191............................................................    54.6
192............................................................    54.6
193............................................................    54.8
194............................................................    55.1
195............................................................    55.5
196............................................................    55.7
197............................................................    56.1
198............................................................    56.3
199............................................................    56.6
200............................................................    56.7
201............................................................    56.7
202............................................................    56.3
203............................................................    56
204............................................................    55
205............................................................    53.4
206............................................................    51.6
207............................................................    51.8
208............................................................    52.1
209............................................................    52.5
210............................................................    53
211............................................................    53.5
212............................................................    54
213............................................................    54.9
214............................................................    55.4
215............................................................    55.6
216............................................................    56
217............................................................    56
218............................................................    55.8
219............................................................    55.2
220............................................................    54.5
221............................................................    53.6
222............................................................    52.5
223............................................................    51.5
224............................................................    50.5
225............................................................    48
226............................................................    44.5
227............................................................    41
228............................................................    37.5
229............................................................    34
230............................................................    30.5
231............................................................    27
232............................................................    23.5
233............................................................    20
234............................................................    16.5
235............................................................    13
236............................................................     9.5
237............................................................     6
238............................................................     2.5
239............................................................     0
------------------------------------------------------------------------


[57 FR 52987, Nov. 5, 1992, as amended at 58 FR 59367, Nov. 9, 1993]

[[Page 266]]



   Subpart T--Conformity to State or Federal Implementation Plans of 
   Transportation Plans, Programs, and Projects Developed, Funded or 
       Approved Under Title 23 U.S.C. or the Federal Transit Laws



Sec. 51.390  Implementation plan revision.

    (a) States with areas subject to this subpart and part 93, subpart 
A, of this chapter must submit to the EPA and DOT a revision to their 
implementation plan which contains criteria and procedures for DOT, MPOs 
and other State or local agencies to assess the conformity of 
transportation plans, programs, and projects, consistent with this 
subpart and part 93, subpart A, of this chapter. This revision is to be 
submitted by November 25, 1994 (or within 12 months of an area's 
redesignation from attainment to nonattainment, if the State has not 
previously submitted such a revision). Further revisions to the 
implementation plan required by amendments to part 93, subpart A, of 
this chapter must be submitted within 12 months of the date of 
publication of such final amendments. EPA will provide DOT with a 30-day 
comment period before taking action to approve or disapprove the 
submission. A State's conformity provisions may contain criteria and 
procedures more stringent than the requirements described in this 
subpart and part 93, subpart A, of this chapter only if the State's 
conformity provisions apply equally to non-federal as well as Federal 
entities.
    (b) The Federal conformity rules under part 93, subpart A, of this 
chapter, in addition to any existing applicable State requirements, 
establish the conformity criteria and procedures necessary to meet the 
requirements of Clean Air Act section 176(c) until such time as EPA 
approves the conformity implementation plan revision required by this 
subpart. Following EPA approval of the State conformity provisions (or a 
portion thereof) in a revision to the applicable implementation plan, 
conformity determinations would be governed by the approved (or approved 
portion of the) State criteria and procedures. The Federal conformity 
regulations contained in part 93, subpart A, of this chapter would apply 
only for the portion, if any, of the State's conformity provisions that 
is not approved by EPA. In addition, any previously applicable 
implementation plan conformity requirements remain enforceable until the 
State submits a revision to its applicable implementation plan to 
specifically remove them and that revision is approved by EPA.
    (c) The implementation plan revision required by this section must 
meet all of the requirements of part 93, subpart A, of this chapter.
    (d) In order for EPA to approve the implementation plan revision 
submitted to EPA and DOT under this subpart, the plan must address all 
requirements of part 93, subpart A, of this chapter in a manner which 
gives them full legal effect. In particular, the revision shall 
incorporate the provisions of the following sections of part 93, subpart 
A, of this chapter in verbatim form, except insofar as needed to clarify 
or to give effect to a stated intent in the revision to establish 
criteria and procedures more stringent than the requirements stated in 
the following sections of this chapter: Secs. 93.101, 93.102, 93.103, 
93.104, 93.106, 93.109, 93.110, 93.111, 93.112, 93.113, 93.114, 93.115, 
93.116, 93.117, 93.118, 93.119, 93.120, 93.121, 93.126, and 93.127.

[62 FR 43801, Aug. 15, 1997]



                 Subpart U--Economic Incentive Programs

    Source: 59 FR 16710, Apr. 7, 1994, unless otherwise noted.



Sec. 51.490  Applicability.

    (a) The rules in this subpart apply to any statutory economic 
incentive program (EIP) submitted to the EPA as an implementation plan 
revision to comply with sections 182(g)(3), 182(g)(5), 187(d)(3), or 
187(g) of the Act. Such programs may be submitted by any authorized 
governmental organization, including States, local governments, and 
Indian governing bodies.
    (b) The provisions contained in these rules, except as explicitly 
exempted, shall also serve as the EPA's policy

[[Page 267]]

guidance on discretionary EIP's submitted as implementation plan 
revisions for any purpose other than to comply with the statutory 
requirements specified in paragraph (a) of this section.



Sec. 51.491  Definitions.

    Act means the Clean Air Act as amended November 15, 1990.
    Actual emissions means the emissions of a pollutant from an affected 
source determined by taking into account actual emission rates 
associated with normal source operation and actual or representative 
production rates (i.e., capacity utilization and hours of operation).
    Affected source means any stationary, area, or mobile source of a 
criteria pollutant(s) to which an EIP applies. This term applies to 
sources explicitly included at the start of a program, as well as 
sources that voluntarily enter (i.e., opt into) the program.
    Allowable emissions means the emissions of a pollutant from an 
affected source determined by taking into account the most stringent of 
all applicable SIP emissions limits and the level of emissions 
consistent with source compliance with all Federal requirements related 
to attainment and maintenance of the NAAQS and the production rate 
associated with the maximum rated capacity and hours of operation 
(unless the source is subject to federally enforceable limits which 
restrict the operating rate, or hours of operation, or both).
    Area sources means stationary and nonroad sources that are too small 
and/or too numerous to be individually included in a stationary source 
emissions inventory.
    Attainment area means any area of the country designated or 
redesignated by the EPA at 40 CFR part 81 in accordance with section 
107(d) as having attained the relevant NAAQS for a given criteria 
pollutant. An area can be an attainment area for some pollutants and a 
nonattainment area for other pollutants.
    Attainment demonstration means the requirement in section 
182(b)(1)(A) of the Act to demonstrate that the specific annual 
emissions reductions included in a SIP are sufficient to attain the 
primary NAAQS by the date applicable to the area.
    Directionally-sound strategies are strategies for which adequate 
procedures to quantify emissions reductions or specify a program 
baseline are not defined as part of the EIP.
    Discretionary economic incentive program means any EIP submitted to 
the EPA as an implementation plan revision for purposes other than to 
comply with the statutory requirements of sections 182(g)(3), 182(g)(5), 
187(d)(3), or 187(g) of the Act.
    Economic incentive program (EIP) means a program which may include 
State established emission fees or a system of marketable permits, or a 
system of State fees on sale or manufacture of products the use of which 
contributes to O3 formation, or any combination of the 
foregoing or other similar measures, as well as incentives and 
requirements to reduce vehicle emissions and vehicle miles traveled in 
the area, including any of the transportation control measures 
identified in section 108(f). Such programs may be directed toward 
stationary, area, and/or mobile sources, to achieve emissions reductions 
milestones, to attain and maintain ambient air quality standards, and/or 
to provide more flexible, lower-cost approaches to meeting environmental 
goals. Such programs are categorized into the following three 
categories: Emission-limiting, market-response, and directionally-sound 
strategies.
    Emission-limiting strategies are strategies that directly specify 
limits on total mass emissions, emission-related parameters (e.g., 
emission rates per unit of production, product content limits), or 
levels of emissions reductions relative to a program baseline that are 
required to be met by affected sources, while providing flexibility to 
sources to reduce the cost of meeting program requirements.
    Indian governing body means the governing body of any tribe, band, 
or group of Indians subject to the jurisdiction of the U.S. and 
recognized by the U.S. as possessing power of self-government.
    Maintenance plan means an implementation plan for an area for which

[[Page 268]]

the State is currently seeking designation or has previously sought 
redesignation to attainment, under section 107(d) of the Act, which 
provides for the continued attainment of the NAAQS.
    Market-response strategies are strategies that create one or more 
incentives for affected sources to reduce emissions, without directly 
specifying limits on emissions or emission-related parameters that 
individual sources or even all sources in the aggregate are required to 
meet.
    Milestones means the reductions in emissions required to be achieved 
pursuant to section 182(b)(1) and the corresponding requirements in 
section 182(c)(2) (B) and (C), 182(d), and 182(e) of the Act for 
O3 nonattainment areas, as well as the reduction in emissions 
of CO equivalent to the total of the specified annual emissions 
reductions required by December 31, 1995, pursuant to section 187(d)(1).
    Mobile sources means on-road (highway) vehicles (e.g., automobiles, 
trucks and motorcycles) and nonroad vehicles (e.g., trains, airplanes, 
agricultural equipment, industrial equipment, construction vehicles, 
off-road motorcycles, and marine vessels).
    National ambient air quality standard (NAAQS) means a standard set 
by the EPA at 40 CFR part 50 under section 109 of the Act.
    Nonattainment area means any area of the country designated by the 
EPA at 40 CFR part 81 in accordance with section 107(d) of the Act as 
nonattainment for one or more criteria pollutants. An area could be a 
nonattainment area for some pollutants and an attainment area for other 
pollutants.
    Nondiscriminatory means that a program in one State does not result 
in discriminatory effects on other States or sources outside the State 
with regard to interstate commerce.
    Program baseline means the level of emissions, or emission-related 
parameter(s), for each affected source or group of affected sources, 
from which program results (e.g., quantifiable emissions reductions) 
shall be determined.
    Program uncertainty factor means a factor applied to discount the 
amount of emissions reductions credited in an implementation plan 
demonstration to account for any strategy-specific uncertainties in an 
EIP.
    Reasonable further progress (RFP) plan means any incremental 
emissions reductions required by the CAA (e.g., section 182(b)) and 
approved by the EPA as meeting these requirements.
    Replicable refers to methods which are sufficiently unambiguous such 
that the same or equivalent results would be obtained by the application 
of the methods by different users.
    RFP baseline means the total of actual volatile organic compounds or 
nitrogen oxides emissions from all anthropogenic sources in an 
O3 nonattainment area during the calendar year 1990 (net of 
growth and adjusted pursuant to section 182(b)(1)(B) of the Act), 
expressed as typical O3 season, weekday emissions.
    Rule compliance factor means a factor applied to discount the amount 
of emissions reductions credited in an implementation plan demonstration 
to account for less-than-complete compliance by the affected sources in 
an EIP.
    Shortfall means the difference between the amount of emissions 
reductions credited in an implementation plan for a particular EIP and 
those that are actually achieved by that EIP, as determined through an 
approved reconciliation process.
    State means State, local government, or Indian-governing body.
    State implementation plan (SIP) means a plan developed by an 
authorized governing body, including States, local governments, and 
Indian-governing bodies, in a nonattainment area, as required under 
titles I & II of the Clean Air Act, and approved by the EPA as meeting 
these same requirements.
    Stationary source means any building, structure, facility or 
installation, other than an area or mobile source, which emits or may 
emit any criteria air pollutant or precursor subject to regulation under 
the Act.
    Statutory economic incentive program means any EIP submitted to the 
EPA as an implementation plan revision to comply with sections 
182(g)(3), 182(g)(5), 187(d)(3), or 187(g) of the Act.
    Surplus means, at a minimum, emissions reductions in excess of an 
established program baseline which are not required by SIP requirements 
or State

[[Page 269]]

regulations, relied upon in any applicable attainment plan or 
demonstration, or credited in any RFP or milestone demonstration, so as 
to prevent the double-counting of emissions reductions.
    Transportation control measure (TCM) is any measure of the types 
listed in section 108(F) of the Act, or any measure in an applicable 
implementation plan directed toward reducing emissions of air pollutants 
from transportation sources by a reduction in vehicle use or changes in 
traffic conditions.



Sec. 51.492  State program election and submittal.

    (a) Extreme O3 nonattainment areas. (1) A State or 
authorized governing body for any extreme O3 nonattainment 
area shall submit a plan revision to implement an EIP, in accordance 
with the requirements of this part, pursuant to section 182(g)(5) of the 
Act, if:
    (i) A required milestone compliance demonstration is not submitted 
within the required period.
    (ii) The Administrator determines that the area has not met any 
applicable milestone.
    (2) The plan revision in paragraph (a)(1) of this section shall be 
submitted within 9 months after such failure or determination, and shall 
be sufficient, in combination with other elements of the SIP, to achieve 
the next milestone.
    (b) Serious CO nonattainment areas. (1) A State or authorized 
governing body for any serious CO nonattainment area shall submit a plan 
revision to implement an EIP, in accordance with the requirements of 
this part, if:
    (i) A milestone demonstration is not submitted within the required 
period, pursuant to section 187(d) of the Act.
    (ii) The Administrator notifies the State, pursuant to section 
187(d) of the Act, that a milestone has not been met.
    (iii) The Administrator determines, pursuant to section 186(b)(2) of 
the Act that the NAAQS for CO has not been attained by the applicable 
date for that area. Such revision shall be submitted within 9 months 
after such failure or determination.
    (2) Submittals made pursuant to paragraphs (b)(1) (i) and (ii) of 
this section shall be sufficient, together with a transportation control 
program, to achieve the specific annual reductions in CO emissions set 
forth in the implementation plan by the attainment date. Submittals made 
pursuant to paragraph (b)(1)(iii) of this section shall be adequate, in 
combination with other elements of the revised plan, to reduce the total 
tonnage of emissions