Transportation Conformity Guidance
on the Revocation of the 1997 Primary
Annual PM2.5 NAAQS
oEPA
United States
Environmental Protection
Agency

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Transportation Conformity Guidance
on the Revocation of the 1997 Primary
Annual PM2.5 NAAQS
Transportation and Climate Division
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
United States
Environmental Protection
^1	Agency
EPA-420-B-16-072
October 2016

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Ql. What is the purpose of this guidance?
This guidance describes how the revocation of the 1997 primary annual PM2.5 national ambient
air quality standard (NAAQS) will be implemented and when transportation conformity stops
applying for this NAAQS.1 It fulfills a commitment EPA made in November 2015 to provide
additional information once EPA finalized the PM2.5 state implementation plan (SIP)
requirements rule. This guidance provides the additional information related to the revocation of
the 1997 primary annual PM2.5 NAAQS that EPA committed to provide in questions 2.2 and 2.3
in its November 2015 guidance concerning transportation conformity requirements for the 2012
primary annual PM2.5 NAAQS. Questions 2.2 and 2.3 in that guidance are now outdated and no
longer apply; however, the remainder of the November 2015 guidance continues to apply.
Background:
In 1997, EPA established an annual PM2.5 NAAQS of 15.0 |ig/m3. That NAAQS served as both
a primary NAAQS to protect public health and a secondary NAAQS to protect against certain
welfare effects such as material damage or soiling of building or other materials. In December
2012, EPA completed a review of the suite of particulate matter NAAQS and concluded that due
to recent studies concerning the health impacts of PM2.5, it was necessary to revise the primary
annual PM2.5 NAAQS to 12.0 |ig/m3. At that time, EPA also concluded that the available
scientific research did not warrant revising the secondary annual PM2.5 NAAQS. Therefore, the
secondary annual PM2.5 NAAQS remains 15.0 |ig/m3.
In November 2015, EPA released a guidance document titled "Transportation Conformity
Guidance for 2012 PM2.5 Nonattainment Areas."2 At the time, the guidance was released, EPA
had separately proposed two options for revoking the 1997 primary annual PM2.5 NAAQS. See
80 FR 15339 (March 23, 2015). The first option was to revoke the 1997 primary annual PM2.5
NAAQS in attainment areas including those that have been redesignated to attainment
(maintenance areas). The second option was to revoke the 1997 primary annual PM2.5 NAAQS
in all nonattainment and attainment areas including all maintenance areas. Because options had
only been proposed and no final action had been taken at that time, EPA could not provide
details on how or when the 1997 primary annual PM2.5 NAAQS would be revoked. EPA
indicated in the November 2015 guidance that we would provide additional information
concerning the revocation when we took final action on the proposal.
EPA took final action on the proposal when it published the "Fine Particulate Matter National
Ambient Air Quality Standards: State Implementation Plan Requirements'" final rule (final PM2.5
SIP requirements rule) on August 24, 2016, see 81 FR 58010 (effective on October 24, 2016). In
that rulemaking, EPA finalized the option that revokes the 1997 primary annual PM2.5 NAAQS
in areas that have always been designated as attainment and in maintenance or that NAAQS.
Additionally, under the finalized option, EPA will continue to redesignate areas to attainment for
the 1997 annual PM2.5 NAAQS, and the 1997 primary annual PM2.5 NAAQS will be revoked in
those areas on the effective date of their redesignation.
1	In general terms, PM2.5 is particulate matter with an aerodynamic diameter of less than or equal to a
nominal 2.5 micrometers (see 81 FR 58010).
2	The guidance is available at: https://nepis.epa.gov/Exe/ZvPDF.cgi?Dockev=P 100NN92.pdf.
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As explained in the preamble to the final rule, EPA believes that revoking the 1997 primary
annual PM2.5 NAAQS is logical because an area that is attaining the more health-protective 2012
primary annual PM2.5 NAAQS is necessarily attaining the less stringent 1997 annual PM2.5
NAAQS by a wide margin. After revocation, areas would no longer have to expend resources on
either Clean Air Act (CAA) air quality planning requirements associated with the 1997 annual
PM2.5 NAAQS or on conformity determinations for that NAAQS. Leaving the 1997 primary
annual PM2.5 NAAQS in place for areas that remain designated nonattainment for that NAAQS
ensures that areas that continue to violate the 1997 annual NAAQS continue to make progress
toward attaining that NAAQS as required by subpart 4 of Title I of the CAA (see 81 FR 58143).
The remainder of this guidance describes in detail how the revocation is implemented and when
transportation conformity no longer applies for the 1997 annual PM2.5 NAAQS.
The Federal Highway Administration (FHWA) and Federal Transit Administration (FTA),
EPA's federal partners in implementing the conformity rule, assisted in the development of this
guidance and concurred on its content.
Q2. Who can I contact for more information ?
For questions concerning a particular 1997 annual PM2.5 NAAQS area, please contact the
transportation conformity staff person responsible for this area at the appropriate EPA Regional
Office. Contact information for EPA Regional Offices can be found on EPA's website at:
https://www.epa.gov/state-and4ocal-transportation/epa-regional-contacts-regarding-state-and-
local-transportation. General questions about this guidance can be directed to EPA's Office of
Transportation and Air Quality: Rudy Kapichak, kapichak.rudolph@epa.gov.
Additional information regarding the transportation conformity rule and associated
guidance can be found on EPA's website at: https://www.epa.gov/state-and-local-
transportation.
Additional information about areas that are nonattainment or have been redesignated to
attainment for the 1997 annual PM2.5 NAAQS can be found at EPA's Green Book web page:
https://www.epa. gov/ green-book.
Q3. Does this guidance create any new requirements?
No, this guidance is based on CAA requirements and existing associated regulations and does
not create any new requirements. This guidance explains how to implement current
transportation conformity requirements in areas that are designated nonattainment for the 1997
annual PM2.5 NAAQS and in those areas that have been redesignated to attainment or will be
redesignated to attainment for the 1997 annual PM2.5 NAAQS.
The CAA and EPA's regulations at 40 CFR Parts 51 and 93 contain legally binding
requirements. This document is not a substitute for those provisions or regulations, nor is this
document a regulation itself. Thus, it does not impose legally binding requirements on EPA, the
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U.S. Department of Transportation (DOT), states, or the regulated community, and may not
apply to a particular situation based upon the circumstances. This guidance may be revised
periodically without public notice.
Q4. Which option to revoke the 1997primary annual PM2.5 NAAQS did EPA finalize?
As noted in Ql, EPA finalized the proposed option that revokes the 1997 primary annual PM2.5
NAAQS in areas that have always been in attainment for that NAAQS, and in maintenance areas
for the 1997 annual PM2.5 NAAQS. The revocation of the 1997 primary annual PM2.5 NAAQS
in these areas occurs on October 24, 2016, which is the effective date of the final PM2.5 SIP
requirements rule (see 81 FR 58010). As a result, the 1997 annual PM2.5 NAAQS remains in
place for current nonattainment areas, it allows the 1997 primary annual PM2.5 NAAQS to be
revoked in the future for a particular nonattainment area, at the point when such an area attains
this NAAQS and is redesignated to attainment.
See EPA's final rule for a detailed discussion on EPA's rationale for finalizing this option {see
81 FR 58141).
Q5. When does transportation conformity no longer apply for the 1997 annual PM2.5
NAAQS?
For areas that have already been redesignated to attainment for the 1997 annual PM2.5 NAAQS,
transportation conformity no longer applies on the effective date of the final PM2.5 SIP
requirements rule, October 24, 2016. After that date, conformity determinations for the 1997
annual PM2.5 NAAQS for metropolitan transportation plans, metropolitan transportation
improvement programs (TIPs), or transportation projects are no longer required in these areas for
this NAAQS.3
For areas that remain designated nonattainment for the 1997 annual PM2.5 NAAQS as of the
effective date of the final PM2.5 SIP requirements rule, transportation conformity requirements
continue to apply for the 1997 annual PM2.5 NAAQS. However, these areas can be redesignated
to attainment in the future. Such future redesignations will apply to both the 1997 primary and
secondary annual PM2.5 NAAQS as has been the case with all past redesignations for this
NAAQS. When such an area is redesignated to attainment, transportation conformity for the
1997 annual PM2.5 NAAQS will cease to apply on the effective date of such an area's
redesignation to attainment for the 1997 annual PM2.5 NAAQS. After that date, conformity
determinations for the 1997 annual PM2.5 NAAQS for metropolitan transportation plans,
metropolitan TIPs, or transportation projects are no longer required in these areas for this
NAAQS.
3 As explained in the final PM2.5 SIP requirements rule transportation conformity does not apply
in areas that have been redesignated to attainment for a secondary NAAQS. This is because
conformity is only required in areas that have been redesignated to attainment if a CAA section
175A maintenance plan is required in order for the area to be redesignated. (See CAA section
176(c)(5)(B)). A CAA section 175A maintenance plan is not required in order for an area to be
redesignated to attainment for a secondary NAAQS. (See CAA section 175A(a) and (b)).
Therefore, conformity does not apply in maintenance areas for a secondary NAAQS.
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Note that in all of the above-described areas, conformity requirements for any other applicable
PM2.5 NAAQS for the areas would continue to apply.
Q6. How many of the 1997 annual PM2.5 NAAQS nonattainment areas have already been
redesignated to attainment?
As of the date of this guidance, 32 of the 39 areas that had been designated nonattainment for the
1997 annual PM2.5 NAAQS have been redesignated to attainment and will have the 1997 primary
annual PM2.5 NAAQS revoked on October 24, 2016, the effective date of the final PM2.5 SIP
requirements rule. Additionally, the Indiana portion of the Louisville, KY-IN area has been
redesignated to attainment for the 1997 annual PM2.5 NAAQS. That NAAQS will be revoked in
the Indiana portion of that area on October 24, 2016. Additional information is included at the
end of this guidance document on the status of areas - Table 1 lists areas that have been
redesignated to attainment for the 1997 annual PM2.5 NAAQS. Transportation conformity for
the 1997 annual PM2.5 NAAQS ceases to apply in these areas on the effective date of the final
PM2.5 SIP requirements rule. Table 2 lists the remaining nonattainment areas for this NAAQS.
Transportation conformity for the 1997 annual PM2.5 NAAQS continues to apply in these areas
until the effective date of their redesignation to attainment.
Q7. Will any area have to make a transportation conformity determination for the 1997
secondary annual PM2.5 NAAQS?
No, there will not be any area that is required to demonstrate conformity solely for the 1997
secondary annual PM2.5 NAAQS.
Under the revocation option that has been finalized, transportation conformity for the 1997
annual PM2.5 NAAQS ceases to apply in areas that have been redesignated to attainment for that
NAAQS as described above.
Areas that remain designated nonattainment for the 1997 annual PM2.5 NAAQS, after the final
PM2.5 SIP requirements rule becomes effective on October 24, 2016, will continue to
demonstrate conformity for the 1997 annual PM2.5 NAAQS as they have in the past until the
effective of such an area's redesignation to attainment for that NAAQS.
As each remaining nonattainment area is redesignated to attainment, transportation conformity
ceases to apply for the 1997 primary annual PM2.5 NAAQS due to the revocation of that NAAQS
and because conformity does not apply in areas that have been redesignated to attainment for the
secondary NAAQS because a CAA section 175 A maintenance plan is not required in order for
an area to be redesignated to attainment for the secondary NAAQS.4 Therefore, on the effective
date of such an area's redesignation to attainment, transportation conformity requirements for the
1997 annual PM2.5 NAAQS will no longer apply.
Areas that are designated nonattainment or are maintenance areas for any other PM2.5 NAAQS
will continue to determine conformity as they have been doing.
4 Transportation conformity only applies to areas that have been redesignated to attainment if
they are required to have an approved CAA section 175A maintenance plan in order to be
redesignated (see CAA section 176(c)(5)(B)).
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Q8. What PM2.5 NAAQS continue to apply for transportation conformity purposes?
Transportation conformity will continue to apply
'or the following PM2.5 NAAQS:
PM2.5 NAAQS*
Level of the NAAQS
(|ig/m3)
Notes
1997 24-hour
65
Conformity applies in the two areas that are
designated nonattainment for this NAAQS.**
1997 annual
15.0
After the effective date of the final PM2.5 SIP
requirements rule conformity for this
NAAQS will continue to apply in areas that
remain designated nonattainment. The
NAAQS will no longer apply for conformity
purposes in the remaining nonattainment
areas on the effective date of such an area's
redesignation to attainment.
2006 24-hour
35
Conformity applies in 32 areas.**
2012 primary annual
12.0
Conformity applies in 9 areas.**
* Unless stated below each PM2.5 NAAQS serves as a primary and secondary with the level and
form of the primary and secondary NAAQS being identical.
** Current as of the date of this guidance release.
Information on nonattainment and maintenance areas for the other PM2.5 NAAQS can be found
on EPA's Green Book web page (https://www.epa.gov/green-book).
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Table 1: Areas that Have Been Redesignated to Attainment (Maintenance Areas) for the
1997 Annual PM2.5 NAAQS as of the Release of this Guidance
Areas Listed Alphabetically
Classification
Number of Counties
Atlanta, GA
Moderate
22
Baltimore, MD
Moderate
6
Birmingham, AL
Former Subpart 1
3
Canton-Massillon, OH
Former Subpart 1
1
Charleston, WV
Former Subpart 1
2
Chattanooga, TN-GA-AL
Moderate
4
Chicago-Gary-Lake County, IL-IN
Former Subpart 1
10
Cincinnati-Hamilton, OH-KY-IN
Former Subpart 1
8
Cleveland-Akron-Lorain, OH
Former Subpart 1
7
Columbus, OH
Former Subpart 1
5
Dayton-Springfield, OH
Former Subpart 1
3
Detroit-Ann Arbor, MI
Former Subpart 1
7
Evansville, IN
Former Subpart 1
6
Greensboro-Winston Salem-High Point, NC
Former Subpart 1
2
Harrisburg-Lebanon-Carlisle, PA
Moderate
3
Hickory-Morganton-Lenoir, NC
Former Subpart 1
1
Huntington-Ashland, WV-KY-OH
Former Subpart 1
9
Indianapolis, IN
Former Subpart 1
5
lohnstown, PA
Moderate
2
Lancaster, PA
Moderate
1
Louisville, IN5
Moderate
3
Macon, GA
Former Subpart 1
2
Martinsburg, WV-Hagerstown, MD
Moderate
2
New York-N. New lersey-Long Island, NY-NI-CT
Former Subpart 1
22
Parkersburg-Marietta, WV-OH
Former Subpart 1
3
Philadelphia-Wilmington, PA-NI-DE
Moderate
9
Pittsburgh-Beaver Valley, PA
Moderate
8
Reading, PA
Moderate
1
Rome, GA
Former Subpart 1
1
Steubenville-Weirton, OH-WV
Former Subpart 1
3
Washington, DC-MD-VA
Moderate
14
Wheeling, WV-OH
Former Subpart 1
3
York, PA
Moderate
1
5 On September 9, 2016 (81 FR 62390) EPA redesignated the Indiana portion of the Louisville
area as attainment for the 1997 annual PM2.5 NAAQS. The redesignation was effective on the
date of publication.
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Table 2: Nonattainment Areas for the 1997 Annual PM2.5 NAAQS as of the Release of this
Guidance
Areas Listed Alphabetically
Classification
Number of Counties
Knoxville, TN
Moderate
5
Libby, MT
Moderate
1
Liberty-Clairton, PA
Moderate
1
Los Angeles-South Coast Air Basin, CA
Moderate
4
Louisville, KY
Moderate
2
San Joaquin Valley, CA
Serious
8
St. Louis, MO-IL
Moderate
9
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