Transportation Conformity Guidance
for 2008 OzoneNonattainment Areas
&EPA
United States
Environmental Protection
Agency
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Transportation Conformity Guidance
for 2008 OzoneNonattainment Areas
Transportation and Climate Division
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
United States
Environmental Protection
Agency
EPA-420-B-12-045
July 2012
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Table of Contents
Table of Contents 1
Section 1. Background 2
1.1 What is the purpose of this guidance? 2
1.2 What is transportation conformity? 4
1.3 Who can I contact for more information? 4
1.4 Does this guidance create any new requirements? 4
Section 2. Implementation of the 2008 Ozone NAAQS and Revocation of the 1997
Ozone NAAQS 6
2.1 When will conformity apply for the 2008 ozone NAAQS? 6
2.2 When will conformity stop applying for the 1997 ozone NAAQS? 6
2.3 What should be considered when making initial 2008 ozone conformity
determinations? 7
2.4 What happens if a 2008 ozone nonattainment area misses the one-year
conformity deadline? 8
2.5 Does conformity apply in tribal areas that have been designated
nonattainment? 8
Section 3. Completing Conformity Determinations for the 2008 Ozone NAAQS 9
3.1 Overview of requirements of a conformity determination for a transportation
plan and TIP for the 2008 ozone NAAQS 9
3.2 Conformity tests for the first conformity determination for the 2008 ozone
NAAQS 10
3.3 Using budgets from a previous ozone NAAQS for 2008 ozone conformity.... 11
3.4 Multi-jurisdictional 2008 ozone areas that have budgets for a previous ozone
NAAQS 12
3.5 Using an interim emissions test to determine 2008 ozone conformity 14
3.6 Multi-jurisdictional 2008 ozone areas using interim emissions tests 15
3.7 Baseline year for the baseline year test 15
3.8 Analysis years for 2008 ozone conformity 16
3.9 Examples for 2008 ozone conformity determinations 17
3.10 Relying on a previous ozone regional emissions analysis when making a
conformity determination for the 2008 ozone NAAQS 19
Section 4. Emissions Models to Be Used When Implementing the 2008 Ozone
NAAQS 21
4.1 What emissions model do I use when completing 2008 ozone conformity
determinations? 21
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Section 1. Background
1.1 What is the purpose of this guidance?
This document provides guidance for meeting transportation conformity requirements in
areas designated nonattainment for the 2008 ozone national ambient air quality standards
("2008 ozone NAAQS"). It also addresses the revocation of the 1997 ozone NAAQS for
transportation conformity purposes.
EPA's final rule designating nonattainment areas for the 2008 ozone NAAQS was
published in the Federal Register on May 21, 2012 and is effective July 20, 2012.l This
rule established initial air quality designations and classifications for the 2008 ozone
NAAQS for most areas in the United States, including areas of Indian country. Details
about the nonattainment designations can be found on EPA's website at:
www.epa.gov/airquality/ozonepollution/designations/2008standards/index.htm.
Concurrent with this designation rule, EPA released an additional final rule that
established the approach for classifying nonattainment areas, set attainment deadlines,
granted reclassification for selected nonattainment areas in California, and revoked the
1997 ozone standard for transportation conformity purposes.3 Areas designated
nonattainment for the 2008 ozone NAAQS were classified into one of the following
categories, based on the severity of their ozone problem: Marginal, Moderate, Serious,
Severe, or Extreme. EPA has established attainment dates for the 2008 primary ozone
NAAQS based on an area's classification, as shown in the following table:4
Classification
Marginal
Moderate
Serious
Severe
Extreme
Attainment Date5
December 3 1,20 15
December 3 1,20 18
December 3 1,2021
December 3 1,2027
December 3 1,203 2
Clean Air Act (CAA) section 176(c)(6) and the conformity regulation at 40 CFR
93.102(d) provide a one-year grace period from the effective date of designations before
transportation conformity applies in areas newly designated nonattainment for a specific
NAAQS. Transportation conformity for the 2008 ozone NAAQS applies one year after
1 77 FR 30088.
2 EPA designated the Chicago-Naperville, IL-IN-WI nonattainment area in a separate final rule (77 FR
34221 (June 11, 2012)), also with an effective date of July 20, 2012.
3 77 FR 30160 (May 21, 2012).
4 Source: Table 4 in 77 FR 30160.
5 Areas may be eligible for attainment date extensions, which is determined through the SIP process and
should not be relevant for the first conformity determination under the 2008 ozone NAAQS. Please consult
the appropriate EPA Regional Office for more information.
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the effective date of nonattainment designations for this NAAQS (i.e., July 20, 2013).
EPA will work with 2008 ozone NAAQS nonattainment areas to help them meet
conformity requirements as they implement this NAAQS. We encourage early
consultation to ensure any questions or issues are addressed in a timely manner. EPA
contact information is provided in Section 1.3.
The guidance is part of EPA's coordinated resources for areas implementing conformity
for the 2008 ozone NAAQS. In preparation for the designation and implementation of
future NAAQS, EPA recently restructured the transportation conformity rule in such a
manner that existing conformity requirements will apply for any new or revised NAAQS;
the conformity rule, therefore, applies directly and does not need to be updated to reflect
the 2008 ozone NAAQS.6
In addition, EPA just released its updated "Guidance for Transportation Conformity
Implementation in Multi-jurisdictional Nonattainment and Maintenance Areas,"
(EPA420-B-12-046, July 2012, referred to hereafter as the "Multi-jurisdictional
Guidance").7 The Multi-jurisdictional Guidance describes how conformity
determinations are made on metropolitan transportation plans and transportation
improvement programs (TIPs) when a nonattainment or maintenance area involves more
than one MPO, more than one state, or both, and describes what conformity tests apply.
Finally, today's guidance is intended to take the information contained in the conformity
rule and the Multi-jurisdictional Guidance and demonstrate how it specifically applies in
the context of the 2008 ozone NAAQS. This should help agencies implementing the
2008 ozone NAAQS address the situations specific to this NAAQS most likely to be
encountered. The Multi-jurisdictional Guidance and this ozone guidance are consistent
with each other as both are based on the conformity regulations.
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.
6 EPA's March 14, 2012 final rule (77 FR 14979; also known as the "Conformity Restructuring Rule")
restructured the transportation conformity rule so that existing conformity requirements will apply for any
new or revised NAAQS. This was done to reduce the need to amend the rule in the future merely to
reference a specific NAAQS and to provide more certainty to transportation planners as conformity
provisions could apply generally to any newly designated NAAQS. Therefore, the transportation
conformity rule does not need to be updated specifically to include implementation of the 2008 ozone
NAAQS. This guidance refers to the appropriate sections of the current rule.
7 The Multi-jurisdictional Guidance can be found on EPA's website at:
www.epa.gov/otaq/stateresources/transconf/policy.htm.
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1.2 What is transportation conformity?
Transportation conformity is required under CAA section 176(c) (42 U.S.C. 7506(c)) to
ensure that federally funded or approved highway and transit activities are consistent with
("conform to") the purpose of the state air quality implementation plan (SIP).
Conformity to the purpose of the SIP means that transportation activities will not cause or
contribute to new air quality violations, worsen existing violations, or delay timely
attainment of the relevant NAAQS or any interim milestones. EPA's transportation
conformity rule (40 CFR Parts 51 and 93) establishes the criteria and procedures for
determining whether metropolitan transportation plans, TIPs, and federally supported
highway and transit projects conform to the SIP. Transportation conformity applies to
designated nonattainment and maintenance areas8 for transportation-related criteria
pollutants: ozone, PM2.5, PMio, carbon monoxide, and nitrogen dioxide.
1.3 Who can I contact for more information ?
For questions concerning a particular 2008 ozone nonattainment 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: www.epa.gov/otaq/stateresources/transconf/contacts.htm
General questions about this guidance can be directed to EPA's Office of Transportation
and Air Quality: David Bizot, bizot.david@epa.gov, (734) 214-4432. or Astrid Larsen,
larsen.astrid@epa.gov. (734) 214-4812.
Additional information regarding the transportation conformity rule and associated
guidance can be found on EPA's website at:
www.epa.gov/otaq/stateresources/transconf/index.htm
Additional information about the 2008 ozone nonattainment designations can be found on
EPA's website at:
www.epa.gov/airqualitv/ozonepollution/designations/2008standards/index.htm
1.4 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 have been designated nonattainment
for the 2008 ozone NAAQS.
8 "Maintenance areas" are those areas that were initially designated nonattainment for a criteria pollutant
and subsequently redesignated to attainment after 1990. Maintenance areas have SIPs developed under
CAA section 175A.
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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
it a regulation itself. Thus, it does not impose legally binding requirements on EPA, the
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.
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Section 2. Implementation of the 2008 Ozone NAAQS and Revocation
of the 1997 Ozone NAAQS
2.1 When will conformity apply for the 2008 ozone NAAQS?
As noted in Section 1.1, CAA section 176(c)(6) and 40 CFR 93.102(d) provide a one-
year grace period from the effective date of designations before transportation conformity
applies in areas newly designated nonattainment for a specific NAAQS. Therefore,
transportation conformity for the 2008 ozone NAAQS does not apply until one year after
the effective date of nonattainment designations for this NAAQS. As EPA's final rule
designating areas for the 2008 ozone NAAQS is effective July 20, 2012, conformity for
this NAAQS applies beginning on July 20, 2013.
Section 2.3 provides further details for how the one-year grace period applies in newly
designated nonattainment areas for the 2008 ozone NAAQS in: 1) areas with an MPO,
and 2) isolated rural areas.
2.2 When will conformity stop applying for the 1997 ozone NAA QS?
EPA's final rule implementing the 2008 ozone NAAQS also revoked the 1997 ozone
NAAQS for transportation conformity purposes. This revocation is effective one year
after the effective date of designations for the 2008 ozone NAAQS (that is, July 20,
2013).9 Therefore, transportation conformity for the 1997 ozone NAAQS stops applying
on that date. This revocation date also corresponds with the end of the one-year
conformity grace period for the 2008 ozone NAAQS.
As explained in the May 2012 classification/revocation rule, this action was taken to
bring certainty to the transportation planning process in ozone nonattainment and
maintenance areas. No backsliding will result from the revocation for purposes of
transportation conformity, as areas designated nonattainment for the 2008 ozone NAAQS
will be required to use any existing adequate or approved SIP motor vehicle emissions
budgets ("budgets") for a prior ozone NAAQS when determining conformity for the 2008
ozone NAAQS until budgets for the 2008 ozone NAAQS are either found adequate or are
approved. Section 3 of this guidance covers how conformity for the 2008 ozone NAAQS
is to be implemented in areas with budgets for a previous ozone NAAQS.
For 1997 ozone nonattainment or maintenance areas that are not designated
nonattainment for the 2008 ozone NAAQS, transportation conformity for the 1997 ozone
NAAQS ceases to apply on July 20, 2013; in such areas, no further conformity
determinations for the 1997 ozone NAAQS or any other ozone NAAQS are required on
or after that date.
9 See 77 FR 30160 (May 21, 2012).
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2.3 What should be considered when making initial 2008 ozone conformity
determinations ?
Nonattainment Areas with One or More MPO
A metropolitan planning organization (MPO)10 and DOT must make a conformity
determination with regard to the 2008 ozone NAAQS for the metropolitan transportation
plan and TIP within one year after the effective date of the initial nonattainment
designation for this NAAQS. The MPO and DOT can make such a conformity
determination anytime during the one-year grace period, as long as the determination is
completed by July 20, 2013. However, if the MPO and DOT miss the deadline, the
nonattainment area would enter a conformity "lapse." See Section 2.4 for more
information on lapses.
MPOs must continue to meet conformity requirements for any other applicable NAAQS,
including the 1997 ozone NAAQS, if the area is designated nonattainment or
maintenance for such other NAAQS.u Determining conformity for these other NAAQS
during the one-year grace period is not necessary unless required by 40 CFR 93.104 (for
example, a new or amended transportation plan and/or TIP are to be adopted). The
procedures for the interagency consultation process found in 40 CFR 93.105 or a state's
approved conformity SIP must be used in making conformity determinations for
transportation plans and TIPs. See Section 3 for more information on interagency
consultation.
Conformity determinations done by an MPO (or MPOs) must also include any donut
areas12 within the 2008 ozone NAAQS area (40 CFR 93.122(a)(l)). Each newly
designated nonattainment area that includes a donut portion must use the interagency
process to determine how best to include donut area emissions in the MPO's regional
emissions analysis and transportation plan and TIP conformity determination (40 CFR
93.105(c)(3) or the state's conformity SIP). For more discussion on how conformity
determinations should be made for donut areas, see the preamble to the July 1, 2004
conformity rule (69 FR 40013) and EPA's Multi-jurisdictional Guidance.
Isolated Rural Nonattainment and Maintenance Areas
In isolated rural areas,13 as in other newly designated nonattainment areas, the one-year
conformity grace period for the 2008 ozone NAAQS will begin on the effective date of
an isolated rural area's initial nonattainment designation. However, because these areas
10 See 40 CFR 93.101 forthe definition of an MPO.
11 Please note that conformity requirements for the 1997 ozone NAAQS cease to apply on July 20, 2013,
when the 1997 ozone NAAQS is revoked for transportation conformity purposes.
12 A donut area is defined in 40 CFR 93.101 as a geographic area outside a metropolitan planning area
boundary, but inside a designated nonattainment or maintenance area boundary that includes an MPO.
13 Isolated rural nonattainment and maintenance areas are defined in 40 CFR 93.101 as areas that do not
contain or are not part of any metropolitan planning area as designated under the transportation planning
regulations.
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do not have federally required metropolitan transportation plans and TIPs, they are not
subject to the frequency requirements for conformity determinations on transportation
plans and TIPs (40 CFR 93.104(b), (c), and (e)). Therefore, such areas are not required
to complete a conformity determination by the end of the one-year grace period. Instead,
in an isolated rural area, a conformity determination is required for the 2008 ozone and
other applicable NAAQS only when a non-exempt FHWA/FTA project(s) needs funding
or approval, based on the conformity requirements for isolated rural areas at 40 CFR
93.109(g).
2.4 What happens if a 2008 ozone nonattainment area misses the one-year
conformity deadline?
If, at the conclusion of the one-year grace period for newly designated areas, the MPO
and DOT have not made a transportation plan and TIP conformity determination for the
2008 ozone NAAQS, the area would be in a conformity lapse. During a conformity
lapse, only certain projects can receive additional federal funding or approvals to proceed
(i.e., exempt projects, project phases that were approved before the lapse, and
transportation control measures (TCMs) in approved SIPs). The practical impact of a
conformity lapse will vary on an area-by-area basis. The lapse grace period found in 40
CFR 93.104(b)(3) and (c)(3) does not apply for newly designated nonattainment areas at
the end of the one-year conformity grace period.14
2.5 Does conformity apply in tribal areas that have been designated
nonattainment?
Yes. Transportation conformity applies in tribal areas that have been designated
nonattainment for the 2008 ozone NAAQS. EPA recommends that the tribe(s), MPO(s),
state department of transportation, DOT, and appropriate EPA Regional Office consult to
determine how to most efficiently conduct conformity determinations for these areas.
Some tribal areas (Indian country) were included in areas designated nonattainment for
the 2008 ozone NAAQS. In most cases, these areas are designated nonattainment as part
of a surrounding area, in which case the tribe was listed by name in 40 CFR Part 81 (in
the table for the 2008 ozone NAAQS) at the time designations were made.15 However, a
few tribal areas were designated as separate nonattainment areas for the 2008 ozone
NAAQS. In these cases, the separately designated nonattainment area was specified in
40 CFR Part 81 along with its associated classification status.
14 See 73 FR 4423-4424 (January 24, 2008) and the Multi-jurisdictional Guidance for additional details
about the lapse grace period.
15 See 77 FR 30088 for the changes made to 40 Part 81 to reflect designations for the 2008 ozone NAAQS.
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Section 3. Completing Conformity Determinations for the 2008 Ozone
NAAQS
The conformity rule provides several tests for determining whether transportation plans,
TIPs, and projects not from a conforming plan or TIP conform, and describes which test
or tests are required in specific circumstances (40 CFR 93.109). The budget test (40 CFR
93.118) is used when an area has either adequate or approved budgets for a pollutant in a
SIP. Therefore, when a 2008 ozone NAAQS area has adequate or approved budgets for
any ozone NAAQS, the budget test requirements in 40 CFR 93.118 must be met. When a
2008 ozone NAAQS area does not have adequate or approved budgets for any ozone
NAAQS, the interim emissions test(s) must be used (40 CFR 93.119). There are also
some cases, prior to 2008 ozone SIP budgets being available, where both the budget test
and interim emissions test(s) are required. How these tests are applied is described in
more detail in this section.
Note that, once 2008 ozone SIP budgets are found adequate or approved, areas must use
the budget test with those budgets to determine 2008 ozone conformity (40 CFR
93.109(c)(l)). This section focuses on how 2008 ozone areas determine conformity
before such 2008 ozone budgets are available (40 CFR 93.109(c)(2) and (3)).
3.1 Overview of requirements of a conformity determination for a transportation
plan and TIP for the 2008 ozone NAAQS
For all areas where transportation conformity applies, including the 2008 ozone areas,
Table 1 found in 40 CFR 93.109(b) lists the conformity criteria that apply for
transportation plans, TIPs, and projects in 40 CFR 93.110 through 93.119.
A transportation plan or TIP conformity determination must include a regional emissions
analysis that meets the requirements of 40 CFR 93.122. This regional emissions analysis
must:
• Use latest planning assumptions (40 CFR 93.110);
• Use the latest emissions model (40 CFR 93.111);16
• Pass the appropriate conformity test - the budget test and/or the interim emissions
test(s) (40 CFR 93.118 and 93.119).
In addition, other requirements must be met and documented in the transportation plan
and TIP conformity determination:
• Interagency consultation and public participation (40 CFR 93.112);
• Timely implementation of TCMs in approved SIPs (40 CFR 93.113).
Please refer to the sections of the transportation conformity regulation noted above for
additional information that is not covered in this guidance.
16 See Section 4 for more information about which emissions model should be used for regional conformity
analyses for the 2008 ozone NAAQS.
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3.2 Conformity tests for the first conformity determination for the 2008 ozone
NAAQS
It is not expected that SIP budgets for the 2008 ozone NAAQS will be available in time
for the first conformity determination. Most if not all 2008 ozone areas will have to rely
on the conformity tests in 40 CFR 93.109(c)(2) and (3).
If 1997 ozone budgets are available for each analysis year in a conformity determination
for the 2008 ozone NAAQS, an area would:
• Use 1997 ozone budgets that are established for that year or the most recent prior
year (see Sections 3.3 and 3.4).17
If no 1997 ozone budgets are available for an analysis year:
• Use 1-hour ozone budgets that are established for that year or the most recent
prior year (see Sections 3.3 and 3.4).
If no ozone budgets are available for an analysis year at all:
• Use the interim emissions test or tests, according to the 2008 ozone area's
classification (see Sections 3.5 through 3.7).
There may be limited cases where both a budget for a previous ozone NAAQS and the
interim emissions test(s) apply (i.e., Scenario 3 and 4 areas, as described in Section 3.3
and Section 3.8).
In addition, the interagency consultation process described in 40 CFR 93.105 must be
used to determine how conformity applies in a specific area. Additional decisions will
need to be made through interagency consultation if the area covers multiple
jurisdictions, for example, if the area includes portions of more than one state, or is
covered by more than one MPO.
EPA will work with DOT and state and local transportation and air quality agencies to
determine which conformity test(s) applies in each 2008 ozone area for the first
determination. See Section 1.3 for EPA contact information.
17 When using the budget test, consistency with budgets must be demonstrated for each year for which there
are adequate or approved ozone budget(s) (40 CFR 93.118(b)) and for analysis years (40 CFR
93.118(d)(2)). In each of these years, emissions must be less than or equal to the budget(s) established for
that year (40 CFR 93.118(b)(l)(i)); when no budget(s) have been established for that year, then emissions
must be less than or equal to budget(s) established for the most recent prior year (40 CFR 93.118(b)(l)(ii)).
A budget cannot be used for an analysis year if it is established for a year later than the analysis year.
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3.3 Using budgets from a previous ozone NAAQSfor 2008 ozone conformity
In general, if an area does not have budgets for the 2008 ozone NAAQS, but has budgets
for a previous ozone NAAQS (i.e., the 1997 ozone NAAQS or 1-hour ozone NAAQS),
these budgets must be used in the budget test. Where such budgets do not cover the
entire area, the interim emissions test(s) may also have to be used (40 CFR
93.109(c)(2)(iii)and(iv)).
A 2006 court decision established the legal parameters for using existing budgets as the
regional conformity test (EnvironmentalDefense v. EPA, 467 F.3d 1329 (DC Cir. 2006)).
EPA incorporated the court's decision for ozone conformity tests in its January 24, 2008
final rule (73 FR 4424). While the court's decision concerned the 1997 ozone NAAQS,
EPA believes the court's holding is relevant for other pollutants and NAAQS for which
conformity must be demonstrated. Therefore, EPA incorporated the court's decision
regarding conformity tests in its March 24, 2010 final rule (the "PM Amendments" rule,
75 FR 14260). Most recently, in its "Conformity Restructuring Rule" (77 FR 14979),
EPA reorganized 40 CFR 93.109(c) so that the court's decision is incorporated in the
regulation for all NAAQS for which conformity applies.
As described in the Conformity Restructuring Rule, there are four generic scenarios for
how an area's boundaries for the relevant NAAQS relate to boundaries covered by
budgets for another NAAQS of the same pollutant. For purposes of the 2008 ozone
NAAQS areas that have budgets from a previous ozone NAAQS, the four scenarios are:
• Scenario 1: Boundaries for both the 2008 ozone NAAQS and previous ozone
NAAQS areas are identical.
• Scenario 2: The boundary of the 2008 ozone area is smaller than and
completely within the area designated for the previous ozone NAAQS.
• Scenario 3: The boundary of the 2008 ozone area is larger than and contains
the area designated for the previous ozone NAAQS.
• Scenario 4: The boundary of the 2008 ozone area overlaps with a portion of
the area designated for the previous ozone NAAQS.
Many areas designated nonattainment for the 2008 ozone NAAQS will be "Scenario 1"
areas (that is, will have identical boundaries for both the 2008 ozone NAAQS and a
previous ozone NAAQS). Consistent with the CAA as interpreted in the court decision
described above, these areas must demonstrate conformity by meeting the budget test for
the 2008 ozone NAAQS using existing adequate or approved SIP budgets for the
previous ozone NAAQS until adequate or approved budgets for the 2008 ozone NAAQS
are effective (40 CFR 93.109(c)(2)(i)).
There are also a number of "Scenario 2" areas, where areas have budgets for a previous
ozone NAAQS that cover an area larger than that designated for the 2008 ozone NAAQS.
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In these cases, the interagency consultation process should be used to determine how to
apply the budget test in those areas (40 CFR 93.109(c)(2)(ii)).
There are a few "Scenario 3" areas, where the 2008 ozone area is larger than the
geographic area covered by the 1997 ozone budgets. In these areas, the interagency
consultation process should be used to determine how to apply the budget test and interim
emissions test(s).18 Refer to the conformity regulation for more information on the
interim emissions tests.
There are also a few "Scenario 4" areas where the 2008 ozone areas overlaps with a
portion of the area designated for the previous ozone NAAQS. In these areas, the
interagency consultation process should be used to determine how to apply the budgets
tests (40 CFR 93.109(c)(2)(iv)).
For all areas, given that there are several factors to consider, such as what previous ozone
budgets are available, the geographic area they cover, and the years in which they are
established, the interagency consultation process should be used to determine what test or
tests will be used for an analysis year and how it should be applied to the area. In
addition, Section 3.9 gives some examples of how the various tests might be applied in
certain 2008 ozone situations.
For areas where subarea budgets for a previous ozone NAAQS are established, or where
budgets for a previous ozone NAAQS are established for individual states in a multi-state
area, EPA's Multi-jurisdictional Guidance also provides guidance on how conformity is
done. Refer to Section 3.4, below, for more information.
3.4 Multi-jurisdictional 2008 ozone areas that have budgets for a previous ozone
NAAQS
For 2008 ozone areas that have budgets for a previous ozone NAAQS but also include
more than one MPO, an MPO and a donut area, and/or more than one state, Section 4 of
the Multi-jurisdictional Guidance provides detailed guidance for preparing conformity
determinations. The most relevant information from the Multi-jurisdictional Guidance
has been adapted and included here for the 2008 ozone NAAQS, but please refer to the
Multi-jurisdictional Guidance for further information regarding how a regional emissions
analysis could be completed for these areas.
One budget covers more than one MPO. Where budgets for a previous ozone NAAQS
cover more than one MPO, the planning agencies will need to work together to develop
one regional emissions analysis for the entire 2008 ozone area, as they have done for the
previous ozone NAAQS (40 CFR 93.124(d)). MPOs must coordinate their transportation
plan/TIP conformity determinations and submit them to DOT. Once DOT receives all
18 For these areas, EPA notes that the regulation at 93.109(c)(2)(iii) provides a choice between meeting the
budget test for the portion of the area that it covers plus the interim emissions test(s), or the budget test for
the entire nonattainment area.
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plan/TIP conformity determinations for the 2008 ozone area, DOT will make its
conformity determinations at the same time. All MPOs within the area must have a
conformity determination for the 2008 ozone NAAQS by the end of the one-year grace
period under 40 CFR 93.102(d). If any do not, DOT will be unable to make any
conformity determinations for the MPOs within the 2008 ozone area and all of the
MPOs' transportation plans and TIPs will lapse.
Subarea budgets. Where subarea budgets19 exist for a previous ozone NAAQS, these
subarea budgets must also be used in the 2008 ozone conformity determinations (40 CFR
93.109(c)(2) and 93.124(d)). Using the existing budgets will ensure that air quality
progress to date is maintained. In general, EPA and DOT believe it is necessary for the
first conformity determination under the 2008 ozone NAAQS to be performed as follows:
each MPO would demonstrate conformity of its transportation plan and TIP to the 2008
ozone NAAQS using the subarea budgets for the previous ozone NAAQS. All of the
MPOs' transportation plan/TIP conformity determinations would then be submitted to
DOT. DOT will not make its conformity determination on any of the transportation plans
or TIPs for the 2008 ozone NAAQS until every MPO in the area has made a conformity
determination for its transportation plan and TIP. All MPOs within the area must have a
conformity determination for the 2008 ozone NAAQS by the end of the one-year grace
period under 40 CFR 93.102(d). If any do not, DOT will be unable to make any
conformity determinations for the MPOs within the 2008 ozone area, and all of the
MPOs' transportation plans and TIPs will lapse.20
Multi-state areas. For multi-state 2008 ozone nonattainment areas, using budgets from a
previous ozone NAAQS (40 CFR 93.109(c)(2)) preserves the ability for MPOs to
determine conformity independently from one another. In other words, MPOs can
operate independently for conformity to the 2008 ozone NAAQS if they have adequate or
approved budgets for a previous ozone NAAQS for their state's portion of the
nonattainment area. Specifically, conformity determinations for the 2008 ozone NAAQS
(including the initial conformity determination) can be made in one state of a multi-state
2008 ozone area if there are adequate or approved budgets for a previous ozone NAAQS
for that state. This is true even if conformity had not yet been determined for the 2008
ozone NAAQS in another state in the area, or if a lapse occurs in another state in the
2008 ozone area.
19 Areas may have subarea budgets when there is more than one MPO in a nonattainment area (within one
state) per 40 CFR 93.124(d); in this case, each MPO must meet its own subarea budgets. See Part 4 of the
Multi-jurisdictional Guidance for more information.
20 In general, for subsequent conformity determinations, the individual MPOs can make conformity
determinations independently as long as all other MPOs in the area have a conforming transportation plan
and TIP in place. If one subarea is in a conformity lapse, conformity determinations for new or revised
plans and TIPs cannot be made in other subareas until the lapse ends.
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3.5 Using an interim emissions test to determine 2008 ozone conformity
As mentioned in Sections 3.2 and 3.3, some 2008 ozone areas will need to use one or
both of the interim emissions tests(40 CFR 93.119(b)). For example, the interim
emissions test(s) must be used if an area does not have adequate or approved budgets for
any ozone NAAQS that it can use for an analysis year. This is expected to be the case for
all analysis years of the conformity determination in ozone areas that are "brand new" to
ozone conformity (that is, have not previously been designated nonattainment for any
previous ozone NAAQS (40 CFR 93.109(c)(3))). The interim emissions test(s) may also
be required in areas with existing ozone budgets that do not cover the entire 2008 ozone
area (Scenario 3 areas, 40 CFR 93.109(c)(2)(iii)). The interim emissions tests include
different versions of the build/no-build test and baseline year test.
When 2008 ozone nonattainment areas must use the interim emissions test(s) for
conformity determinations conducted before adequate or approved 2008 ozone SIP
budgets are established (40 CFR 93.119):
Areas classified Moderate and above for the 2008 ozone NAAQS must conduct both of
these tests:
• The build-less-than-no-build test (40 CFR 93.119(b)(l)(i)). In this test, the
transportation emissions reflecting the proposed transportation plan or TIP in the
analysis year (the "build" or "action scenario") must be less than the emissions
from the transportation system that would result in that same analysis year from
current programs only (the "no-build" or "baseline scenario") (40 CFR
93.119(h));and
• The less-than-baseline year emissions test (40 CFR 93.119(b)(l)(ii)). In this test,
the transportation emissions reflecting the proposed transportation plan or TIP in
the analysis year (the "build" or "action scenario") must be lower than the
emissions level of motor vehicle emissions in the baseline year by any nonzero
amount. The baseline year for 2008 ozone conformity is 2011. Refer to Section
3.7 for more on the baseline year test.
Areas classified Marginal for the 2008 ozone NAAQS must choose to conduct one of
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these tests:
• The build-no-greater-than-no-build test (40 CFR 93.119(b)(2)(i)). In this test, the
transportation emissions reflecting the proposed transportation plan or TIP in the
analysis year (the "build" or "action scenario") must not be greater than the
emissions from the transportation system that would result in that same analysis
21 This would also include any 2008 ozone NAAQS areas classified less than Marginal, of which none are
at this time.
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year from current programs only (the "no-build" or "baseline scenario") (40 CFR
93.119(h));or
• The no-greater-than-baseline year emissions test (40 CFR 93.119(b)(2)(ii)). In
this test, the transportation emissions reflecting the proposed transportation plan
or TIP in the analysis year (the "build" or "action scenario") must not be greater
than the level of motor vehicle emissions in the baseline year. Refer to Section
3.7 for more on the baseline year test.
Where 2008 ozone areas that must use the interim emissions test(s) contain more than
one MPO and/or a donut portion, there are additional considerations. Refer to Section
3.6 for additional information about applying interim emissions tests in multi-
jurisdictional areas.
3.6 Multi-jurisdictional 2008 ozone areas using interim emissions tests
Any multi-jurisdictional area using one or both of the interim emissions tests will want to
refer to Part 2 of the Multi-jurisdictional Guidance, which covers conformity
determinations and regional emissions analyses before SIP budgets are adequate or
approved, and specifically addresses the following topics:
• The geographic area to be examined in a regional emissions analysis and
conformity determination before the area has adequate or approved budgets
(Section 2.3 of Multi-jurisdictional Guidance);
• How multi-jurisdictional areas can create a regional emissions analysis for the
entire nonattainment area (Section 2.4 of Multi-jurisdictional Guidance);
• The decisions to be made in the interagency consultation process (Section 2.5 of
the Multi-jurisdictional Guidance); and
• What occurs when one MPO can meet the requirements in 40 CFR 93.119 when
another MPO or donut area cannot (Section 2.6 of the Multi-jurisdictional
Guidance).
3.7 Baseline year for the baseline year test
For any NAAQS promulgated after 1997, the conformity rule at 40 CFR 93.119(e)(4)
defines the baseline year for the baseline year test as the most recent year for which
EPA's Air Emissions Reporting Rule requires submission of on-road mobile source
emissions inventories as of the effective date of designations.22 For the 2008 ozone
NAAQS, this year is 2011. Conformity determinations using the baseline year test as an
interim emissions test must therefore use 2011 as the baseline year. See
www.epa.gov/otaq/stateresources/transconf/baseline.htm for more information on
baseline years.
22 This change was made in the final Conformity Restructuring Rule (77 FR 14979).
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Note that the baseline year emissions need to be modeled rather than interpolated, based
on the latest planning assumptions, latest emissions model and appropriate methods for
estimating travel and speeds as required by 40 CFR 93.110, 93.111, and 93.122. See
Section 4.1 for more information about emissions models to be used when implementing
the 2008 ozone NAAQS.
3.8 Analysis years for 2008 ozone conformity
The years required to be analyzed for 2008 ozone conformity depends on what test(s) are
being used to demonstrate conformity for a particular area.
When using the budget test
When using the budget test for the 2008 ozone NAAQS, 40 CFR 93.122(d)(2) requires
the regional emissions analysis to be performed for:
• The attainment year for the 2008 ozone NAAQS, if it is within the timeframe of
the transportation plan and conformity determination,
• The last year of the timeframe of the conformity determination, and
• Intermediate years as necessary, such that analysis years are no more than ten
years apart.
Note that the analysis years chosen must meet 40 CFR 93.118(d)(2) for all NAAQS that
apply. During the one-year grace period for newly designated 2008 ozone areas when the
1997 ozone NAAQS also applies, the 2008 ozone areas with adequate or approved 1997
ozone budgets can determine conformity for both of these NAAQS at the same time. See
Section 1.1 for the attainment years for the 2008 ozone NAAQS.
In addition, in areas that have budgets for a previous ozone NAAQS that are established
for years in the timeframe of the conformity determination, consistency with those
budgets must also be determined (40 CFR 93.118(b)). This consistency can be
demonstrated by interpolating between the years for which regional emissions analyses
are performed (40 CFR 93.118(d)(2)).23
When using an interim emissions test
Regardless of whether the area is required to use the baseline year test and/or the
build/no-build test, the required analysis years when using an interim emissions test,
based on 40 CFR 93.119(g)(l), are:
• A year no more than 5 years beyond the year in which the conformity
determination is being made;
• The last year of the timeframe of the conformity determination, and
• Intermediate years as necessary, such that analysis years are not more than ten
years apart.
23 Interpolating emissions for a particular year is only possible when an analysis has been done for a year
earlier and a year later than that year.
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When using a combination of both the budget test and an interim emissions test(s)
In cases when both the budget test and an interim emissions test(s) are used to
demonstrate conformity to the 2008 ozone NAAQS, the interagency consultation process
must be used to determine which analysis years should be selected for regional emissions
analyses. This situation may occur either because budgets are not available for some
analysis years24 or because budgets do not cover the entire 2008 ozone area. The area
may choose analysis years that satisfy both the budget and interim emissions test
requirements (40 CFR 93.118(d)(2) and 93.119(g)(l)).
The EPA Regional Office is available to discuss what analysis years apply in different
situations. See EPA contact information in Section 1.2.
3.9 Examples for 2008 ozone conformity determinations
Below are several hypothetical examples of how an area would apply the conformity tests
given different scenarios, budgets, and analysis years. These examples are presumed to
occur before the effective date of revocation for the 1997 ozone NAAQS, and in
Examples 1 and 2, these hypothetical areas have chosen to determine conformity for both
the 1997 and 2008 ozone NAAQS at the same time. The examples also note how the
analysis would change after the 1997 ozone NAAQS is revoked.
Example 1
A 1997 ozone nonattainment area is designated nonattainment for the 2008 ozone
NAAQS and is a Scenario 1 area (i.e., the boundaries of the 1997 ozone NAAQS and
2008 ozone NAAQS areas are identical). The area has 1997 ozone budgets for years
2012, 2017, and 2018. The area is classified Marginal for the 2008 ozone NAAQS with
an attainment year of 2015.
In March 2013, the MPO is making a conformity determination for both the 1997 and
2008 ozone NAAQS for its transportation plan and TIP. The transportation plan runs
through 2035. In addition to needing to analyze 2015 and 2018 (its attainment years for
the 2008 and 1997 ozone NAAQS, respectively) and 2035 (the last year of the timeframe
of the conformity determination), the area decides to analyze 2025 (an intermediate year
so that analysis years are no more than 10 years apart).
24 There can be limited cases where an area has a budget for another NAAQS of the same pollutant that
cannot be used for all analysis years because it is established for a later year. When this occurs, the interim
emissions test(s) would be used for analysis years that are earlier than the budget year. For example,
suppose there is a 2008 ozone area that is a Scenario 1 area. This area has 1997 ozone NAAQS
maintenance budgets for the year 2022, and that is the only year for which ozone budgets exist. In this
case, the 2008 ozone area must use the budget test according to 40 CFR 93.118 for 2022 and later years,
and the interim emissions test(s) according to 40 CFR 93.119 for analysis years earlier than 2022.
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This table summarizes how the conformity tests would be done for this example:
Year
2015
2017
2018
2025
2035
Analysis Required? (40 CFR 93.118(d)(2))
Yes - attainment year for 2008 ozone NAAQS
No - only "demonstrate consistency" required,
so emissions can be interpolated
Yes - attainment year for 1997 ozone NAAQS
Yes - intermediate year
Yes - last year of the transportation plan
Test Used
1997 ozone budgets for 2012
1997 ozone budgets for 2017
1997 ozone budgets for 2018
1997 ozone budgets for 2018
1997 ozone budgets for 2018
As previously noted, this table assumes this conformity determination will be completed
prior to the effective date of revocation for the 1997 ozone NAAQS (before July 20,
2013). After that date, there would be no need to analyze 2018 (this area's attainment
year for the 1997 ozone NAAQS) because conformity for the 1997 ozone NAAQS will
no longer apply. Instead, consistency with the 1997 ozone NAAQS budgets for the 2018
budget year could be determined through interpolation. The remainder of the table would
remain unchanged.
Example 2
An area is designated nonattainment for the 1997 and 2008 ozone NAAQS and was
previously a maintenance area for the 1-hour NAAQS. It is a Scenario 1 area with regard
to both previous ozone NAAQS (e.g., the boundaries of the 1-hour, 1997 and 2008 ozone
NAAQS areas are all identical). The area has adequate 1-hour ozone budgets for 2012
and 1997 ozone maintenance plan budgets for 2022. The area is classified Marginal for
the 2008 ozone NAAQS with a 2015 attainment year. The area's 1997 ozone NAAQS
attainment year is no longer in the timeframe of the transportation plan.
It is March 2013 and this area is making its 1997 and 2008 ozone conformity
determinations for its transportation plan and TIP. The transportation plan ends in 2040.
In addition to needing to analyze 2015 (its 2008 ozone NAAQS attainment year) and
2040 (the last year of timeframe of conformity determination), the area decides to analyze
2020 and 2030 (intermediate years so that analysis years are no more than 10 years
apart).
This table summarizes how the conformity tests would be done for this example:
Year
2015
2020
2022
2030
2040
Analysis Required? (40 CFR 93.118(d)(2))
Yes - attainment year for 2008 ozone
NAAQS
Yes - intermediate year
No - only "demonstrate consistency"
required, so emissions can be interpolated
Yes - intermediate year
Yes - last year of the transportation plan
Test Used
1-hour ozone budgets for 2012
1-hour ozone budgets for 2012
1997 ozone budgets for 2022
1997 ozone budgets for 2022
1997 ozone budgets for 2022
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Note that, while in this example the area chose to analyze 2020 as an intermediate year, it
could have selected a different year and still met the requirement that analysis years be no
more than ten years apart. It could have, for example, selected 2022 as an intermediate
year (in which case it would use the 1997 ozone budgets for 2022 and complete an
analysis for that year instead of demonstrating consistency) or 2025 (in which it still
would need to determine consistency with the 1997 ozone budgets in 2022).
Example 3
An area is designated nonattainment for the 2008 ozone NAAQS and classified as
Marginal. This area was not designated nonattainment for any prior ozone NAAQS and
therefore does not have any previous ozone budgets.
It is March 2013 and this area is making its initial 2008 ozone conformity determination
for its transportation plan and TIP. The transportation plan ends in 2035. In addition to
needing to analyze 2035 (the last year of the timeframe of the conformity determination),
the area decides to analyze 2015 (a year within five years of the year the conformity
determination is being made) and 2025 (an intermediate year so that analysis years are no
more than 10 years apart).
This table summarizes how the conformity tests would be done for this example:
Year
2015
2025
2035
Analysis Required? (40 CFR 93.119(g))
Yes - a year within five years of the year
the conformity determination is being
made
Yes - intermediate year
Yes - last year of the transportation plan
Test Used
Thebuild-no-greater-than-no-build
test or
The no-greater-than-baseline year
emissions test
Same as above
Same as above
Note that only one of the interim emissions tests is required because the area is classified
Marginal. The area would select from the two available tests and use the same test for all
the analysis years.
3.10 Relying on a previous ozone regional emissions analysis when making a
conformity determination for the 2008 ozone NAAQS
A 2008 ozone NAAQS area can rely upon a regional emissions analysis completed for
the 1997 ozone NAAQS, provided that it meets the requirements in 40 CFR 93.122(g).
In particular, the regionally significant projects in the transportation plan/TIP must be
consistent with those assumed in the previous regional emissions analysis, and the design
concept and scope of each regionally significant project cannot be significantly different
from that assumed in the previous regional emissions analysis. In addition, the previous
regional emissions analysis must be consistent with the requirements of 40 CFR 93.118
or 93.119, as appropriate. In particular, if the budget test is being performed, the 2008
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ozone attainment year must be included as an analysis year, and the regional emissions
analysis must demonstrate conformity to all currently applicable budgets.
If the previous emissions analysis did not analyze the 2008 ozone NAAQS attainment
year, an area cannot rely upon 40 CFR 93.122(g) for some years and perform a new
analysis just for the new attainment year. However, if nothing else has changed for
previous analysis years and emissions would be exactly the same as what would be
generated if a new analysis was performed (i.e., the planned projects, latest planning
assumptions, and emissions models have not changed), the modeling for those analysis
years would not have to be repeated. In these cases, an area could include the applicable
analyses from the previous conformity determination in its new determination.
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Section 4. Emissions Models to Be Used When Implementing the 2008
Ozone NAAQS
4. 1 What emissions model do I use when completing 2008 ozone conformity
determinations ?
The conformity rule requires that conformity determinations must be based on the latest
emissions model available (40 CFR 93. 1 1 1).
UsingMOVES2010
In March 2010, EPA announced the release of the MOtor Vehicle Emissions Simulator
(MOVES2010).25 EPA subsequently released two minor model revisions: MOVES2010a
in September 2010 and MOVES2010b in April 2012. Both of these minor revisions
enhance model performance and do not significantly affect the criteria pollutant
emissions results from MOVES2010. See www. epa. gov/otaq/model s/moves/ for more
information about MOVES2010, MOVES2010a, and MOVES2010b.
MOVES will be required for new regional conformity analyses for the 2008 ozone
NAAQS areas outside of California that begin after March 2, 2013 (or when EPA finds
adequate or approves MOVES-based 1997 or 2008 ozone NAAQS budgets for an area,
whichever comes first). Upon the release of MOVES2010, EPA established a two-year
grace period before MOVES was required to be used for regional conformity
determinations (75 FR 941 1). EPA subsequently promulgated a final rule to provide an
additional year before MOVES is required for these analyses (77 FR 1 1394). The
MOVES grace period for regional conformity analyses applies to both the use of
MOVES2010 and approved minor revisions, including MOVES2010a and
MOVES2010b.
Areas with budgets for a previous ozone NAAQS that were prepared using MOBILE
should consider the impacts of needing to use MOVES for future transportation plan and
TIP conformity determinations. Through interagency consultation, these areas can decide
whether and when SIPs and budgets can be revised with MOVES (or transportation plan
and TIPs can be revised, as appropriate) prior to the end of the regional conformity grace
period. Areas can also consider whether MOBILE6.2 should be used for the first
conformity determination for the 2008 ozone NAAQS. If so, the regional emissions
analysis must begin by March 2, 2013, the end of the MOVES2010 grace period (40 CFR
For further information on the implementation of the MOVES regional conformity grace
period, see EPA's "Policy Guidance on the Use of MOVES2010 and Subsequent Minor
Model Revisions for State Implementation Plan Development, Transportation
Conformity, and Other Purposes" (EPA-420-B-12-010, April 2012), available online at:
www.epa.gov/otaq/stateresources/transconf/policy.htmtfmodels. In addition, for
25 75 FR 9411.
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information regarding how to use MOVES for SIP development for the 2008 ozone
NAAQS, see Question 5 of EPA's "Policy Guidance on the Use of MOVES2010 and
Subsequent Minor Revisions for State Implementation Plan Development, Transportation
Conformity, and Other Purposes" (EPA-420-B-12-010; April 2012).
Using EMFAC2007
EMFAC2007 is currently the latest approved model for use in transportation conformity
analyses in California and should be used for all regional conformity analyses for the
2008 ozone NAAQS until EPA announces otherwise. EPA is aware that EMFAC2011
has been released by the California Air Resources Board and is currently reviewing that
model. However, EMFAC2011 should not be used for any conformity analyses until
EPA officially approves the model for that purpose. EPA will release additional details
about how that model is to be used for transportation conformity purposes, along with
any conformity grace period, at the time it approves the model.
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