If wildfire impacts are significant, contributing to exceedances of the standard, states should consider RACM for this source. Fires play an important ecological role across the globe, benefiting those plant and animal species that depend upon natural fires for propagation, habitat restoration, and reproduction. Fires are one tool that can be used to reduce fuel load, unnatural understory, and tree density, helping to reduce the risk of catastrophic wildfires. The use of prescribed fire can influence the occurrence of catastrophic wildfires which may reduce the probability of fire-induced ozone impacts and subsequent public health effects. RACM for wildfire may include addressing the wildland fuels through fuels management and including the use of prescribed fire in systems that are ecologically fire dependent. Where appropriate, states may consider developing plans for addressing wildland fuels in collaboration with land managers and owners. RACM for prescribed fires should also be considered. Information is available from DOI and the USDA Forest Service on smoke management programs and basic smoke management practices and may be considered when determining RACM for prescribed fires. RACM must be determined for each area on a case-by-case basis.
c. Comments and Responses
      Comment: One commenter suggested amending RACM guidance to follow the same common-sense approach proposed for RACT; i.e., if studies show that reducing anthropogenic VOC emissions in an area has little effect on ground-level ozone concentrations, RACM analyses should not be required for that pollutant.
      Response: We note that existing EPA guidance already provides some assistance to states with identifying the type of measures that might be considered for RACM (See General Preamble, 57 FR 13549, April 16, 1992). If a state demonstrates that implementation of VOC emission reduction measures will not contribute to an area's reasonable further progress or to attainment, then additional control of VOC emissions does not need to be further considered for RACM purposes. Thus, the EPA concludes that it need not amend RACM guidance to address this comment.
E. Does the 2008 ozone NAAQS result in any new vehicle I/M programs?
	Based on current designations and classifications for the 2008 ozone NAAQS, no new vehicle I/M programs are currently required. In the proposal for this rulemaking, the EPA provided information on potential ways a state could design and implement an I/M program, either because it was required to implement a program due to a future reclassification for the 2008 ozone NAAQS, as a result of a nonattainment designation and classification under a future standard, or because an area decided to implement an I/M program even though it was not otherwise required. That discussion is not repeated here; therefore, please refer to the proposal (78 FR 34194-34196). Although the EPA is finalizing its proposal to revise the I/M SIP due date to align it with other SIP due dates (see section III.A of this preamble), no other changes are being made to the EPA's existing regulations and guidance on vehicle I/M programs.
F. How does transportation conformity apply to the 2008 ozone NAAQS?
1. What is transportation conformity?
      Transportation conformity is required under CAA section 176(c) to ensure that transportation plans, transportation improvement programs (TIPs) and federally supported highway and transit projects are consistent with ("conform to") the purpose of the SIP. Conformity to the purpose of the SIP means that transportation activities will not cause new air quality violations, worsen existing violations, or delay timely attainment of the relevant NAAQS or interim reductions and milestones. Transportation conformity applies to areas that are designated nonattainment, and to those former nonattainment areas that have been redesignated to attainment since 1990 and have a CAA section 175A maintenance plan ("maintenance areas") for transportation-related criteria pollutants: carbon monoxide, ozone, nitrogen dioxide and particulate matter.
      The EPA's Transportation Conformity Rule (40 CFR 51.390 and part 93, subpart A) establishes the criteria and procedures for determining whether transportation activities conform to the SIP. The EPA first promulgated the Transportation Conformity Rule on November 24, 1993 (58 FR 62188), and subsequently published several amendments. For example, the EPA published a final rule on July 1, 2004 (69 FR 40004) that provided transportation conformity procedures for state and local agencies under the 1997 ozone NAAQS, among other things. Parties involved in implementing transportation conformity include state and local transportation and air quality agencies, metropolitan planning organizations (MPOs) and the U.S. Department of Transportation (the DOT) (40 CFR 93.102). For further information on transportation conformity rulemakings, policy guidance and outreach materials, see the EPA's website at http://www.epa.gov/otaq/stateresources/transconf/index.htm.
2. When would transportation conformity apply to areas designated nonattainment for the 2008 ozone NAAQS?
      Transportation conformity for the 2008 ozone NAAQS applied 1 year after the effective date of nonattainment designations for the NAAQS. CAA section 176(c)(6) and 40 CFR 93.102(d) provide a 1-year grace period from the effective date of an initial designation of nonattainment before transportation conformity applies in the area for a particular pollutant and standard. For areas designated nonattainment effective July 20, 2012, the 1-year grace period ended on July 20, 2013. For any area subsequently redesignated to nonattainment (from unclassifiable or attainment), the 1-year grace period runs from the effective date of the redesignation. The grace period requirements differ depending on whether the nonattainment area is a metropolitan area or an isolated rural area.
      In metropolitan areas, which are defined as urbanized areas that have a population greater than 50,000 and a designated MPO responsible for transportation planning per 23 U.S.C. 134, within 1 year after the effective date of the nonattainment designation, the area's MPO and the DOT must make a conformity determination with regard to the area's transportation plan and TIP for the 2008 ozone NAAQS under the transportation conformity regulations ( 40 CFR 51.390 and part 93, subpart A). The conformity requirements for "donut areas," including the application of the 1-year conformity grace period, are generally the same as those for metropolitan areas. If, at the end of the grace period, the MPO and the DOT have not made a transportation plan and TIP conformity determination for the relevant pollutant and standard, the area would be in a conformity "lapse." During a conformity lapse, only certain projects can receive additional federal funding or approvals to proceed. The practical impact of a conformity lapse will vary from area to area.
      Isolated rural nonattainment areas are areas that do not contain or are not part of an MPO (40 CFR 93.101). Conformity requirements for isolated rural nonattainment areas can be found at 40 CFR 93.109(g). An isolated rural area would be required to make a conformity determination only at the point when a new transportation project needs funding or approval. This point may occur significantly after the 1-year grace period has ended. See the EPA's July 1, 2004, final rule for further background on how the EPA has implemented this conformity grace period for the 1997 ozone NAAQS in metropolitan, donut and isolated rural areas (69 FR 40008-40014).
3. Does transportation conformity apply for the 1997 ozone NAAQS once that NAAQS is revoked?
      The CAA only requires transportation conformity in areas that are designated nonattainment or maintenance for a given pollutant and standard. Therefore, transportation conformity would no longer apply for purposes of the 1997 ozone NAAQS as of the time that standard (and thus an area's designation for that standard) is revoked. Accordingly, existing 1997 ozone NAAQS nonattainment and maintenance areas, regardless of their designation for the 2008 ozone NAAQS, would no longer be required to demonstrate transportation conformity for the 1997 ozone NAAQS after the 1997 ozone NAAQS is revoked. The D.C. Circuit ruled that the EPA violated the CAA when it attempted to revoke the 1997 ozone NAAQS for transportation conformity purposes only in the Classifications Rule for the 2008 ozone NAAQS. The attempted revocation would have become effective on July 20, 2013, 1 year after the effective date of designations for the 2008 ozone NAAQS. (77 FR 30160) The D.C. Circuit Court of Appeals said nothing to suggest that the EPA could not revoke the standard for all purposes, as it is doing today. See South Coast, (upholding revocation of standard so long as anti-backsliding measures are introduced).  Under our current Transportation Conformity Rule, the latest approved or adequate emission budgets for a previous ozone NAAQS (i.e., the 1997 or the 1-hour ozone NAAQS) would continue to be used in conformity determinations for the 2008 ozone NAAQS until emission budgets are established and found adequate or are approved for the 2008 ozone NAAQS. (77 FR 14981-2)
4. What impact will the implementation of the 2008 ozone NAAQS have on a state's
Transportation Conformity SIP?
      States with previously approved Transportation Conformity SIPs should not need to revise those SIPs, unless they need to do so to ensure that existing state regulations apply in areas newly designated nonattainment for the 2008 ozone NAAQS. However, if this is the first time that transportation conformity will apply in a state, such a state is required to submit a SIP revision within 12 months of the effective date of the nonattainment designation that covers the three specific transportation conformity requirements that are delineated in CAA section 176(c)(4)(E). These specific requirements are consultation procedures and written commitments to control or mitigation measures associated with conformity determinations for transportation plans, TIPs or projects. 40 CFR 51.390. Additional information and guidance can be found in EPA's "Guidance for Developing Transportation Conformity State Implementation Plans" (http://www.epa.gov/otaq/stateresources/transconf/policy/420b09001.pdf).
G. What requirements for general conformity apply to the 2008 ozone NAAQS??
1. Summary of the Proposal
      The EPA did not propose to make revisions to the General Conformity Regulations. However, we did recommend that as areas develop their SIPs for the 2008 ozone NAAQS, state and local air quality agencies work with federal agencies with major facilities that are subject to the General Conformity Regulations to establish an emissions budget for those facilities in order to facilitate future conformity determinations. Significant tracts of land under federal management may also be included in nonattainment area boundaries. The role of fire in these areas should be assessed and emissions budgets developed in concert with those federal land management agencies. Where appropriate, states may consider developing plans for addressing wildland fuels in collaboration with land managers and owners. Information is available from DOI and USDA Forest Service on the ecological role of fire and on smoke management programs and basic smoke management practices and may be considered as potential mitigation measures to lessen the impacts of wildfires. We also stated in the proposal that for the ozone precursors VOC and NOx, the existing de minimis emission levels contained in 40 CFR 93.153(b)(1) will continue to apply to the 2008 ozone NAAQS. We also stated in the proposal that general conformity for the 2008 ozone NAAQS would apply 1 year after the effective date of nonattainment designations for that NAAQS because section 176(c)(6) provides a 1-year grace period from the effective date of initial designations before general conformity determinations are required in areas newly designated nonattainment for a particular pollutant and standard. In such areas we encourage states to consider in any baseline inventory used and/or submitted to include emissions expected from projects to general conformity, including emissions from wildland fire that may be reasonably expected in the area.
      Since we proposed to revoke the 1997 ozone NAAQS at the time the final SIP Requirements Rule is published in the Federal Register, we stated in the proposal that general conformity requirements under the 1997 ozone NAAQS would end after the 2008 ozone NAAQS general conformity requirements begin.
2. Final Action and Rationale
      The EPA is taking no action to revise General Conformity Regulations. For reasons explained in section IV of this rule, we are revoking the 1997 ozone NAAQS 30 days after publication of this final rule. Accordingly, the general conformity requirements for the 1997 ozone NAAQS will end when the NAAQS is revoked, and the general conformity requirements for the 2008 ozone NAAQS are applicable 1 year after the effective date of nonattainment designations for the 2008 NAAQS. The EPA believes the existing General Conformity Regulations (40 CFR part 93) remain appropriate for the 2008 ozone NAAQS. States with approved general conformity SIPs should not need to revise their SIPs unless they need to do so to ensure they are consistent with the April 5, 2010, revisions to the general conformity regulations or to ensure the existing regulations apply in the appropriate newly designated areas.
H. What are the requirements for contingency measures in the event of failure to meet a milestone or to attain?
1. Summary of Proposal
      The EPA proposed that the contingency measures required for Moderate and above areas under CAA sections 172(c)(9) and 182(c)(9) must provide for the implementation of specific measures if the area fails to attain or to meet any applicable milestone. These measures must be submitted for approval into the SIP as adopted measures that would take effect without further rulemaking action by the state or the Administrator upon a determination that an area failed to attain or to meet the applicable milestone. Per the EPA guidance, contingency measures should represent 1-year's worth of progress, amounting to reductions of 3 percent of the baseline emissions inventory for the nonattainment area, which would be achieved while the state is revising its plans for the area.
      Regarding the content of the contingency measures, the EPA's prior guidance specifies that some portion of the contingency measures must include VOC reductions. As explained in the proposal, this previous limitation is no longer necessary in all cases.  In particular, Moderate and above areas that have completed the initial 15 percent VOC reduction required by CAA section 182(b)(1)(A)(i), can meet the contingency measures requirement based entirely on NOx controls if that is what the state's analyses have demonstrated would be most effective in bringing the area into attainment. There would be no minimum VOC requirement. Also, the EPA proposed continuing its long-standing policy that allows promulgated federal measures to be used as contingency measures as long as they provide emission reductions in the relevant years in excess of those needed for attainment or RFP.
      The EPA also proposed an implementation approach for Extreme nonattainment areas whereby plan provisions meeting the requirements of section 182(e)(5) (referred to as the "black box"), including the requirements concerning contingency measures, therein, may satisfy the section 172(c)(9) and 182(c)(9) contingency measure requirements for the area provided the state has already adopted all reasonable candidate measures in the applicable SIP to satisfy RACM, RFP, and all other requirements necessary for attainment in the area.
2. Final Action and Rationale
      The EPA is finalizing the proposed requirements that contingency measures must be submitted for approval into the SIP as required by the CAA and must provide for the implementation of specific measures without any further rulemaking action if the area fails to attain or meet any applicable milestone, with limited exceptions for Extreme nonattainment areas relying on plan provisions approved under section 182(e)(5), as discussed below. Regarding content of the 1-year's worth of emissions covered by the contingency measures, the EPA is finalizing its proposal to allow the 3 percent emissions reductions of the contingency measures, to be based entirely on NOx controls if the area has completed the initial 15 percent ROP VOC reduction required by CAA section 182(b)(1)(A)(i) and the state's analyses have demonstrated that NOx substitution would be most effective in bringing the area into attainment.
      The EPA will continue to allow the use of federal measures providing ongoing reductions into the future to be used meet contingency measure requirements for the 2008 ozone NAAQS, consistent with the EPA's longstanding policy. The EPA has previously approved the use of federal measures to meet contingency measure requirements in actions approving 1-hour and 8-hour ozone SIPs.
      With respect to Extreme ozone nonattainment areas, section 182(e)(5) allows the agency to exercise discretion in approving Extreme area attainment plans that rely, in part, on the future development of new control technologies or improvements of existing control technologies, where certain conditions are met. This discretion can be applied as long as the state has demonstrated that: all reasonably available control measures, including RACT, have been included in the plan; the area's RFP demonstration during the first 10 years after designation does not rely on anticipated future technologies; and the state has submitted enforceable commitments to timely develop and adopt contingency measures to be implemented if the anticipated future technologies do not achieve planned reductions. The EPA is finalizing its proposal to allow states to submit, for Extreme nonattainment areas, enforceable commitments to develop and adopt contingency measures meeting the requirements of 182(e)(5) to satisfy the requirements for both attainment contingency measures in sections 172(c)(9) and 182(c)(9). These enforceable commitments must obligate the state to submit the required contingency measures to the EPA no later than three years before any applicable implementation date, in accordance with section 182(e)(5). We note that this does not, however, relieve states from obligations to submit contingency plans as required by sections 172(c)(9) and 182(c)(9) for periods in the first 10 years after designation.
3. Comments and Responses
      Comment: Commenters urged the EPA to provide flexibility to states when adopting, subject to EPA approval, contingency measures into the SIP that are ready for implementation should the area fail to either meet milestones or attain. Commenters requested that the EPA allow air quality improvement measurements to be taken into consideration for purposes of evaluating the level of emission reductions necessary to meet the contingency measure requirements when providing "approximately" 1 year's worth of progress for contingency measures. Commenters indicated that a similar air quality improvements approach has been used in approving PM2.5 contingency measures.
      Response: The EPA's long-standing interpretation is that a 3 percent emissions reduction from the RFP baseline, rather than a specific ozone concentration improvement, is the minimum contingency measure adoption requirement under subpart 2. The EPA did not propose to alter this guidance. However, we note that if the contingency measures are ever triggered for an area, states may take air quality considerations into account in determining whether a subset of measures amounting to less than 3 percent emissions reduction are all that is necessary to be implemented to cure the identified failure. The implementation of PM2.5 NAAQS is governed by statutory and regulatory requirements that are separate from, and not identical to, ozone implementation and provide flexibility for states to consider the degree of air quality improvement that may be needed in developing RFP plans and contingency measures.
	Comment: Several commenters supported, and no commenters objected to using section 182(e)(5) authority to approve contingency measure plans for Extreme nonattainment areas where the attainment plan is based on development of new or improved control measures.
      Response: We appreciate the supportive comments. We recognize that all areas must meet the contingency plan requirements of sections 172(c)(9) and 182(c)(9). We agree that CAA section 182(e)(5) provides the agency discretion to approve an Extreme area attainment plan that relies, in part, on the future development of new control technologies or improvements of existing control technologies. This authority can be exercised as long as the state has demonstrated that: all reasonably available control measures, including RACT, have been included in the plan; the area's RFP demonstration during the first 10 years after designation does not rely on anticipated future technologies; and the state has submitted enforceable commitments to timely develop and adopt contingency measures in the event that anticipated future technologies do not achieve planned reductions.
      Comment: One commenter argued that an Extreme nonattainment area seeking to rely on the section 182(e)(5) "black box" should be required to demonstrate that it has adopted all feasible controls, even if they do not advance attainment by a year and regardless of whether they constitute "reasonably available control measures," and that the EPA should "change its interpretation of RACT and RACM, which currently allows areas to avoid adopting and implementing feasible measures."
      Response: The EPA believes that both its long-standing interpretation of RACM and its focus on whether control measures are "reasonably available" provide an appropriate framework for determining when to exercise the discretion provided by section 182(e)(5). As noted in the proposal, the determination of whether a SIP contains all RACM requires an area-specific analysis establishing that there are no additional economically and technically feasible control measures (alone or cumulatively) that will advance the attainment date by 1 year. This requires close review of any measure that a commenter identifies as reasonably available for implementation in the area in light of local circumstances, and of measures being implemented in other states. 78 FR 34187, at 34194 (June 6, 2013). This interpretation of RACM has been upheld in court (e.g., Sierra Club v. EPA, 294 F.3d 155, 162-163 (D.C. Cir. 2002)). Thus, the EPA believes that it is appropriate to require that an area seeking to rely on the anticipated development of new technology demonstrate that its plan includes all control measures that come within this definition of "reasonably available." The EPA does not believe it is necessary for an area to demonstrate the use of measures that go beyond that definition in order to meet contingency measure requirements.
I. How do the NSR requirements apply for the 2008 ozone NAAQS?
1. Major NSR Requirements for the 2008 Ozone NAAQS
      The NSR programs established in parts C and D of title I of the CAA contain specific requirements for the preconstruction review and permitting of new or modified major stationary sources of air pollutants. In attainment and unclassifiable areas outside the OTR, the requirements under part C apply for the prevention of significant deterioration (PSD) program. In nonattainment areas and throughout the OTR, the requirements under part D apply for the nonattainment NSR program. We commonly refer to the PSD and nonattainment NSR programs together as the "major NSR programs."
      The regulations for the major NSR programs are contained in 40 CFR 51.166 and 52.21 for PSD, and 51.165, 52.24 and part 51, Appendix S for nonattainment NSR. Among other things, in unclassifiable and attainment areas outside of the OTR, the PSD program requires a new major source, or a major modification to an existing major source, to obtain a permit that satisfies PSD requirements, including the application of best available control technology (BACT) for "each pollutant subject to regulation under [the CAA]," conducting an air quality impact analysis, and complying with requirements related to the protection of Class I areas.
      As part of the required air quality impact analyses, section 165(a)(3) of the CAA provides that the owner or operator of a proposed facility must, among other things, demonstrate that "emissions from construction or operation of such facility will not cause, or contribute to, air pollution in excess of any ... national ambient air quality standard in any air control region." The EPA has generally interpreted this statutory requirement, and the corresponding regulations implementing EPA's federal PSD permitting program at 40 CFR 52.21(k) and establishing minimum requirements for PSD programs approved into SIPs at 40 CFR 51.166(k), to include a demonstration for any NAAQS that is in effect at the time a final permit decision is issued. See, e.g., 73 FR 28321, 28324, 28340 (May 16, 2008); 78 FR 3253 (Jan. 15, 2013); Memorandum from Stephen D. Page, Director, Office of Air Quality Planning & Standards, entitled "Applicability of the Federal Prevention of Significant Deterioration Permit Requirements to New and Revised National Ambient Air Quality Standards," to the EPA Regional Air Division Directors and Deputies (April 1, 2010).
      In the proposal, the EPA indicated that, since the May 27, 2008, effective date of the 2008 ozone NAAQS, permit applications for new major stationary sources and major modifications have been subject to the PSD program requirements for ozone under two sets of circumstances: First, prior to the designation of areas for the 2008 ozone NAAQS, sources locating in areas designated attainment or unclassifiable for the 1997 ozone NAAQS; and second, on and after the July 20, 2012, effective date of area designations for the 2008 ozone NAAQS, sources locating in areas designated as attainment or unclassifiable for both the 1997 and 2008 ozone NAAQS. If, however, an area was designated attainment or unclassifiable for the 2008 ozone NAAQS on and after July 20, 2012, but was designated nonattainment for the 1997 ozone NAAQS, consistent with the PSD regulations at 40 CFR 51.166(i)(2) and 52.21(i)(2), the nonattainment designation would require application of nonattainment NSR for permits issued to new and modified sources locating in that area that trigger major NSR requirements for ozone until the revocation of the 1997 ozone NAAQS is effective. In this rulemaking, the EPA is revoking the 1997 ozone NAAQS for all purposes. Accordingly, as explained in section IV.A of this preamble, as of 30 days after the publication of this rule in the Federal Register, the area designations for the 1997 ozone NAAQS will no longer be considered current designations; thus, all areas designated attainment for the 2008 ozone NAAQS will be subject to PSD requirements. In the proposal, the EPA explained that this result was based on its interpretation of the PSD regulations at 40 CFR 51.166(i)(2) and 52.21(i)(2), but recognized that those provisions did not expressly say that a nonattainment designation for a revoked standard does not trigger the exemption from PSD requirements contained in those provisions. 78 FR 34216-17. Accordingly, the EPA requested comment on whether amendment of 40 CFR 51.166(i)(2) and 52.21(i)(2) is necessary to achieve that outcome and on how such an amendment, if any, should be worded. After additional consideration, we believe there is a need for us to amend these provisions to further clarify the application of the exemption they contain. Therefore, the EPA is amending its PSD regulations at 40 CFR 51.166(i)(2) and 52.21(i)(2) as a logical outgrowth of the proposal and the submitted comments to clarify that historical designations for a revoked NAAQS should not be considered in determining whether PSD requirements apply for that pollutant once the revocation becomes effective in an area.
      For any area that is designated nonattainment for the 2008 ozone NAAQS, the historical designations and classifications resulting from the revoked 1997 ozone NAAQS will continue to serve to identify nonattainment NSR anti-backsliding requirements (i.e., major source thresholds and emissions offset ratios) that need to be taken into account in issuing nonattainment NSR permits to major stationary sources and
major modifications. As indicated previously, the designations and classifications for the revoked standard should not be regarded as current designations and classifications once the revocation takes effect. For example, in implementing the emissions offset requirements for nonattainment NSR, offset ratios based on the classification for the revoked standard, to the extent more stringent than the ratios for the 2008 ozone NAAQS classification, must be used for anti-backsliding purposes. However, for purposes of determining whether a prospective offset can be obtained from a nonattainment area other than the one in which a new or modified source would be located, the requirements under section 173(c)(1) of the CAA must be satisfied. Section 173(c)(1) requires, in part, that the nonattainment area from which the offset is obtained must have "an equal or higher nonattainment classification than the area in which the [new or modified] source is located...." After the revocation takes effect, the historical classification for the revoked NAAQS, to the extent that it is lower than the classification in the nonattainment area where a new or modified source would be located, would not preclude obtaining the offset from that area, so long as (1) the current classification for the ozone NAAQS for that area is equal to or higher than the current classification of the nonattainment area where the new or modified source is locating and (2) the other requirements under section 173(c)(1) of the CAA are satisfied.
      Some states may have already in their SIP a nonattainment NSR program consistent with part D of the CAA that can be applied to new nonattainment areas. In such situations, permitting authorities should have begun applying the nonattainment NSR requirements in permitting actions for new and modified major sources that trigger major source permitting requirements for ozone in new nonattainment areas starting from the effective date of the 2008 ozone designations (July 20, 2012).
      For a newly designated (or redesignated) nonattainment area for the 2008 ozone NAAQS in a state with a SIP that specifically lists the areas in which nonattainment NSR requirements under part D apply, or in a state that currently has no approved nonattainment NSR program, there will be an interim period between the July 20, 2012 designation date and the date when the EPA approves the state's amended SIP, which must be revised to adequately address the nonattainment NSR requirements for the 2008 ozone NAAQS contained in this final rule. In the proposal, we explained that during this interim period, nonattainment NSR requirements for the 2008 NAAQS are governed by the EPA's Emission Offset Interpretative Ruling codified in Appendix S to 40 CFR part 51. Among other things, in general, Appendix S requires new or modified major sources in nonattainment areas to meet the lowest achievable emission rate (LAER) and obtain sufficient offsetting emissions reductions to assure that the new or modified major sources will not interfere with the area's progress toward attainment. In addition, a new section VII of Appendix S has been added as part of this final rule to set forth the anti-backsliding requirements that must be addressed in order to issue a nonattainment NSR permit under Appendix S. That language for section VII is being finalized with only minor modifications to what was proposed. Readers should refer to 40 CFR part 51, Appendix S for a better understanding of the Appendix S permitting requirements.
      In the proposal, the EPA explained that the time period for the NSR waiver provision contained in section VI of Appendix S, enabling permitting authorities in specified circumstances to issue nonattainment NSR permits that do not require LAER or emissions offsets as are otherwise required under section IV of appendix S, was limited by the court's ruling in NRDC v. EPA, 571 F.3d 1245 (D.C. Cir. 2009). The court's ruling was the result of a petition filed in response to the EPA's Phase 2 Rule for the 1997 ozone NAAQS in which the EPA revised 40 CFR 52.24(k). The revision to paragraph (k) eliminated language stating that if a nonattainment area did not have an approved nonattainment NSR program within 18 months after designation, Appendix S would no longer apply and a construction ban would apply instead. 70 FR 71612 (November 29, 2005). The effect of the revision was to extend the applicability of Appendix S, including the section VI waiver provision, to cover the full period from the date of designation to the date on which the EPA approved the nonattainment NSR SIP for a new NAAQS.
      In NRDC v. EPA (571 F.3d 1245 (D.C. Cir. 2009)), the court vacated "the elimination of the 18-month time limit for NSR waivers under Appendix S" on the grounds that it violated section 172(e) of the CAA (571 F.3d at 1276). As a result of the court's vacatur of the extension of the 18-month time limit for section VI of Appendix S, no section VI waivers may be granted beyond 18 months from the date of designation for any NAAQS.
      Several commenters requested that the EPA clarify how the court's decision affects the implementation of Appendix S as an interim nonattainment NSR program. While most commenters understood that the vacatur applied only to the removal of the 18-month deadline for the section VI waiver, one commenter seemed to interpret the vacatur to apply to appendix S in its entirety.
	To clarify, there is now a distinction between the length of time during which waivers may be granted under section VI of Appendix S and the length of time the remainder of Appendix S applies as an interim nonattainment NSR program. No section VI waivers may be granted beyond 18 months from the date of designation. The remainder of Appendix S, however, is not subject to an 18-month time limitation. It will remain as the basis for air agencies to issue nonattainment NSR permits in new ozone nonattainment areas until the EPA approves a state's nonattainment NSR program for the 2008 ozone NAAQS under the SIP for the area. Specifically, section IV of Appendix S contains preconstruction requirements for proposed sources and modifications, which reflect the requirements contained in part D of the CAA for ozone nonattainment areas. The requirements in section IV should be met consistent with the anti-backsliding requirements contained in new section VII of Appendix S.
2. Offset Requirements and Policy
      To satisfy requirements under section 173 of the Act, new and modified major sources in nonattainment areas must secure emissions reductions (i.e., "offsets") to compensate for a proposed emissions increase. Offsets are generated by emissions reductions that meet specific creditability criteria set forth by the SIP consistent with EPA regulations. See, 40 CFR 51.165(a)(3)(ii)(A)-(J) and part 51 Appendix S section IV.C.  One commenter suggested that nonattainment NSR major source construction and major modification offsets should be available outside the nonattainment area (from attainment areas) due to the possibility that new sources would develop in attainment areas in close proximity to the boundary of the ozone nonattainment area with subsequent impact on the nonattainment area. Further, the commenter seemed to suggest that emissions reductions from these close proximity sources should also be allowed to be used as offsets within the adjacent nonattainment area. The commenter's suggestion fails to address the statutory requirements for offsets and, more specifically, does not confront the statutory provisions restricting where offsets can be obtained from. In accordance with the requirements under section 173(c)(1) of the CAA, emissions offsets must be obtained from the same nonattainment area, except that the state may allow a source to obtain offsets from another nonattainment area if (1) that area has an equal or higher nonattainment classification than the nonattainment area in which the source requiring the offsets is located, and (2) emissions from that other area contribute to a violation of the NAAQS in the nonattainment area in which the source requiring the offsets is located. Accordingly, the EPA does not intend to revise the existing requirements as to where emissions offsets may be obtained to allow use of offsets from attainment areas.
3. Facilitating New Source Growth in Nonattainment Areas
a. Offset Banks
      States can help facilitate continued economic development in a nonattainment area by establishing offset banks or registries. Such banks or registries can help new or modified major stationary source owners meet offset requirements by streamlining identification and access to available emissions reductions. Some states have established offset banks to help ensure a consistent method for generating and transferring NOx and VOC offsets. Offsets in these areas are generated by emissions reductions that meet specific creditability criteria set forth by the SIP consistent with EPA regulations. See existing 40 CFR 51.165(a)(3)(ii)(A)-(J) and part 51 Appendix S section IV.C.
b. Interprecursor Offset Substitution
      In the proposal, the EPA recognized that states could establish interprecursor offset substitution provisions, which would create additional flexibility in meeting offset requirements by allowing NOx emissions reductions to satisfy VOC offset requirements and vice versa. See 78 FR at 34201. The EPA received no adverse comments on whether to allow such interprecursor trading for ozone and no comment suggested that such trading is not or should not be allowed for ozone. In fact, all comments addressing the EPA's statements in the proposal concerning interprecursor trades for ozone for nonattainment NSR permitting were in support of allowing NOx emissions reductions to satisfy VOC offset requirements and vice versa.
      Although there were no adverse comments relating to the EPA's ability to allow interprecursor trading for ozone, the EPA recognizes that the current language of 40 CFR 51.165(a)(11) and part 51 Appendix S IV.G.5 could be read to limit interprecursor trading to PM2.5, and thus to preclude this kind of interprecursor trading for ozone precursors (NOx and VOC). However, the EPA has issued previous guidance that clearly allows for such interprecursor trading for ozone precursors. While the EPA did not specifically propose to amend the nonattainment NSR regulations to address interprecursor trading for ozone, the proposal indicated the EPA's intent to continue to allow states to establish provisions that allow for such interprecursor trading for ozone precursors.
      As noted previously, the EPA received no adverse comments on the interprecursor aspect of the proposal. Commenters did, however, indicate support for ensuring in the final rulemaking that interpollutant trading would continue to be allowed, and one commenter indicated support for measures similar to what was authorized in the final 2008 PM2.5 NAAQS implementation rule, (see 73 FR 28321) which revised the regulations and Appendix S to allow for interprecursor trading for PM2.5 precursors.
      Accordingly, the EPA is taking action in this final rulemaking to amend the regulatory text in both section 51.165 and Appendix S as a logical outgrowth of the proposal and the submitted comments to ensure that the offset provisions of both rules are consistent with our proposal and our ongoing position to allow such trades for the ozone precursors (VOC and NOx). See revised 40 CFR 51.165(a)(11) and part 51 Appendix S IV.G.5. These changes in the regulatory text are intended to clarify that interprecursor trading continues to be an option for the ozone precursors VOC and NOx, as long as such trades are consistent with existing policy and legal requirements; these revisions are not intended to change the underlying requirements for such trades. Please refer to the Response to Comments document in the docket for this rulemaking for more detailed information and responses to comments with respect to interprecursor trading concerns.
c. Economic Development Zones (EDZs)
	Section 173(a)(1)(B) of the CAA authorizes the Administrator, in consultation with the Secretary of Housing and Urban Development (HUD), to identify areas within nonattainment areas as "zone[s] to which economic development should be targeted." Under this section, new or modified major stationary sources that locate in such a zone are relieved of the NSR requirement to obtain emission offsets if (1) the relevant SIP includes an NSR nonattainment program that has established emission levels for new and modified major sources in the zone ("growth allowance"), and (2) the emissions from new or modified stationary sources in the zone will not cause or contribute to emission levels that exceed such growth allowance. Section 172(c)(4) of the CAA requires that the growth allowance be consistent with the achievement of reasonable further progress, and that it will not interfere with attainment of the applicable NAAQS by the applicable attainment date for the nonattainment area. The EPA is willing to work with HUD and states to identify potential areas that could be identified as EDZs.
4. Deadline for Submitting Nonattainment NSR Program SIPs for 2008 ozone NAAQS

As explained in section III.A of this preamble, several commenters noted that the EPA's proposed rulemaking did not address the SIP submittal deadline for the nonattainment NSR program for the 2008 ozone NAAQS. As explained in section III.A, the final rule includes a deadline of 3 years from the effective date of designation for states to submit their nonattainment NSR program SIPs for the 2008 ozone NAAQS. The rationale for this deadline appears in section III.A of this preamble.
J. What are the emission inventory and emission statement requirements?
1. Emission Inventory Requirements
a. Summary of the Proposal
	We proposed that states should rely on their 3-year cycle inventory as described by the Air Emissions Reporting Requirements (AERR) to meet 182(a)(3)(A) periodic inventory obligations and that the emissions reporting requirements of the AERR be applied to determine all of the data elements required for such inventories (see, e.g., Tables 2A, 2B, 2C and 2D of 40 CFR part 51, subpart A, Appendix A). We also proposed to follow our existing guidance, titled "Public Hearing Requirements for 1990 Base-Year Emissions Inventories for Ozone and Carbon Monoxide Nonattainment Areas" in implementing certain SIP adoption and submission procedures for the emissions inventory requirements under CAA sections 182(a)(1) and 182(a)(3)(A) for purposes of the 2008 ozone NAAQS.
b. Final Action and Rationale
      We are generally finalizing as proposed, although in light of comments received we made small changes to address reporting of ozone season day and partial county emissions not currently addressed in the AERR, as explained below. CAA section 182(a)(3)(A) requires that states submit periodic emission inventories no later than the end of each 3-year period after submission of the base year inventory for the nonattainment area. This requirement applies to Marginal and above ozone nonattainment areas. Thus, states must submit this periodic inventory no later than the end of each 3-year period after submission of the base year inventory for the nonattainment area. The periodic inventory required by this final rule must include ozone season day emissions of VOC and NOx for point, nonpoint and mobile sources (on-road and non-road) and fire-related event emissions. On December 4, 2008, the EPA promulgated the AERR rule (40 CFR 51, subpart A). The AERR requires states to submit comprehensive statewide 3-year cycle annual emission inventories (2008, 2011, 2014, etc.) for a number of pollutants  (see list provided at 40 CFR 51.15(a)) regardless of an area's attainment status. During the submission of the 3-year cycle inventories in accordance with the AERR, states may also submit ozone season day emissions to meet the periodic inventory requirement of this rule. If the periodic inventory required by this rule is not included in the AERR submission, then it must be submitted to the EPA through other mechanisms in coordination with the Regional Office. Emission inventory elements submitted per the AERR that are relied on in the SIP also need to be adopted through the SIP submittal requirements per. Section 51.100 et seq.
      We are finalizing the requirement that states use the reporting requirements of the AERR to determine the data elements required for such inventories, while including an additional requirement to report ozone season day emissions, as defined in this final rule, rather than the AERR requirement for annual emissions for both the base year inventory for the nonattainment area and the periodic inventory. Additionally, the EPA has included within section 51.1100(bb) and (cc) of this final rule definitions pertaining to base year inventory and the ozone season day emissions, in response to several significant comments as explained in section III.J.1.c. Accordingly, a base year inventory for the nonattainment area is due no later than 2 years after the effective date of designations, and the emissions included in this inventory must be ozone season day emissions as defined in section 51.1100(cc) of this rule. A periodic inventory must be submitted on intervals no later than the end of each 3-year period after submission of the base year inventory for the nonattainment area.
      The EPA has concluded that ozone season day emissions are the most appropriate temporal basis for developing the emissions to be included in this inventory, rather than summer day emissions as required by past implementation rules or the AERR. The EPA believes that summer day emissions required previously are an insufficient nomenclature, since in some areas nonattainment may be due to ozone exceedances in months other than summer months (e.g., wintertime), and necessitate focusing planning efforts on emissions occurring during the most relevant time period. Other than changing the name to be more inclusive, the definition of the emissions to be included is essentially the same as the previous definition. Ozone season day emissions means an average day's emissions for a typical ozone season work weekday section as defined in section 51.1100(cc). The state will select, subject to EPA approval, the particular month(s) in the ozone season and the day(s) in the work week to be represented. The selection of days should be coordinated with the conditions assumed in the development of RFP plans and/or emissions budgets for transportation conformity to allow comparability of daily emissions estimates. The days should represent the conditions that contribute to high ozone that led to a nonattainment designation.
      For all inventories submitted to the EPA for this rule, states must use the reporting requirements of the AERR to determine which sources are reported as point sources as well as the detail (i.e., data elements) required for such inventories, with the exception of the emissions values. The emissions values must be ozone season day emissions rather than the AERR requirement for annual emissions for both the base year inventory for the nonattainment area and the periodic inventory.
      Inventories of partial-county nonattainment areas must match the spatial extent of the nonattainment area to include only emissions within the nonattainment area. The EPA acknowledges the challenges associated with partial county inventories and has prepared an updated draft of the emissions inventory guidance (see below) to provide additional information for air agencies to use in preparing partial county emissions. The base year inventory for the nonattainment area is used as the baseline for RFP plans to achieve emissions reductions within the nonattainment area. As explained more fully in section III.C of this preamble, the EPA has determined that emissions reductions in areas outside the nonattainment area cannot be included in the area's RFP demonstration. Thus, the EPA has concluded that for nonattainment areas with partial county boundaries, all inventories must be developed to reflect the partial county boundaries. This requirement partly supersedes the requirement to use the AERR data elements, such that for nonpoint and mobile sources, the county field required by the AERR should be replaced by a separate identifier to indicate the partial county nonattainment area. Because of this partial difference in requirements, periodic inventories for partial county nonattainment areas cannot be reported to the EPA as part of a state's AERR/NEI triennial inventory submission. Instead, states must make available the inventory data to the EPA as electronic files in some other electronic media, such as FTP, zip drives, or DVDs.
      For all inventories that are used in developing RFP plans or attainment demonstrations, mobile source emissions should be estimated using the latest emissions models, data and planning assumptions available at the time the SIP is developed. The latest approved models should be used to estimate emissions from on-road and non-road sources, in combination with the latest available estimates of vehicle miles traveled (VMT), vehicle population, and/or equipment activity. States are advised to check the EPA web pages for the currently approved mobile source models and to consult with the EPA Office of Transportation and Air Quality and their Regional Office to determine the versions of models to use for their SIPs for the 2008 ozone NAAQS. For on-road mobile emissions in states other than California, the current approved version of MOVES, as well as links to the Federal Register Notice approving that version, and links to guidance documents with much more detail on when and how MOVES should be used can be found at: http://www.epa.gov/otaq/models/moves/index.htm. For California, consult with the EPA Region 9 Office for the information on the latest approved version of the EMFAC (EMissions FACtors) model. Emissions from non-road equipment should be estimated with the latest official version of the EPA's NONROAD model, and other appropriate methods for estimating emissions from sources not covered by these models. Links to Federal Register notices and policy guidance memos on the latest approved versions of MOVES and NONROAD can be found at http://www.epa.gov/otaq/models.htm.
      Additional information is available to states for all emissions sources and quality assurance in the form of guidance. States should consult the latest version of the guidance document "Emission Inventory Guidance for Implementation of Ozone and Particulate Matter National Ambient Air Quality Standards (NAAQS) and Regional Haze Regulations," EPA - 454/R - 05 - 001 (latest final November 2005; revised draft April 2014) and any subsequent updates to that guidance that the EPA makes available (which can be found at http://www.epa.gov/ttn/chief/eidocs/eiguid/index.html). States should submit inventories that are appropriate for each nonattainment area and consistent with the EPA's guidance.
      As indicated previously, some inventories submitted to meet the requirements of section 182(a)(1) and 182(a)(3)(A) may be used in the development of RFP plans and/or attainment demonstrations. The EPA expects that the base year inventory for the nonattainment area will serve as the RFP plan baseline. As such, the EPA requires the methodologies used to develop these inventories to be clearly documented and the inventories themselves to be subject to public participation requirements and formal approval/disapproval by the EPA.
	The EPA is not finalizing the proposed approach, where we advised that states could follow our existing September 29, 1992, guidance, titled, "Public Hearing Requirements for 1990 Base-Year Emissions Inventories for Ozone and Carbon Monoxide Nonattainment Areas" in implementing certain SIP adoption and submission procedures for the emissions inventory requirements under CAA sections 182(a)(1) and 182(a)(3)(A) for purposes of the 2008 ozone NAAQS. In that guidance, the EPA indicated it could provide states with a time-limited "de minimis" deferral of the CAA's state public hearing requirement for the emissions inventory SIP revision required to be submitted for each nonattainment area within 2 years of the date of designation. The EPA continues to believe that there are valid policy reasons to provide such a deferral since the inventories alone do not have significant regulatory context without the accompanying area-specific RFP plans or attainment plans, which are not required to be submitted until the 3[rd] year after designations at the earliest. However, as a general matter the CAA clearly requires that SIP submittals, including emissions inventories (see CAA sections 182(a)(1) and 182(a)(3)(A)), must meet the requirements of CAA section 110(a)(2), which includes the requirement that the state provide reasonable notice and public hearing for SIP submittals. As there is nothing in these CAA provisions that provides for waiver or delay of the public notification and hearing requirements specified in CAA section 110(a) de minimis or otherwise, we no longer believe it is appropriate to advise states to follow the 1992 guidance. We instead remind states that the EPA's implementing regulations at 40 CFR Part 51 (Requirements for Preparation, Adoption, and Submittal of Implementation Plans) provide flexibility for states to streamline SIP-related public notification and hearing procedures (for example, only holding a public hearing if one is requested, per 40 CFR § 51.102), and we encourage states to take advantage of those provisions in meeting the emissions inventory requirements under CAA sections 182(a)(1) and 182(a)(3)(A).
c. Comments and Responses
      Commenters provided a variety of comments on issues relating to emissions inventories. A full accounting of those comments and the EPA's detailed responses are further explained in the Response to Comments document contained in the docket. Significant comments were made that resulted in small changes from the proposed rule. In particular, commenters noted that the proposed rule failed to clearly indicate the need for seasonal or summer day emissions values in the required inventories and for use in the RFP plan. Different commenters suggested different terms, time periods, and emissions bases to use in the inventories and plans, including summer day, typical summer day, high ozone season day, and maximum daily. These comments and others noted the discrepancy with this rule and proposed changes to the AERR, in that seasonal emissions were not expressly required by either the proposed ozone requirements rule or the proposed AERR changes. As a result of these comments, the EPA has included the requirement in this rule as a logical outgrowth for ozone season day emissions, as defined in this final rule, to be used in emission inventories submitted for ozone SIPs. One commenter noted that partial county areas are not expressly addressed in the emissions inventory requirements and pointed out that it will be burdensome for states to create partial county inventories. The EPA addresses partial county emissions in this final rule by specifically defining the emissions to be included as "within the boundaries of the nonattainment area" and clarifies in this preamble that such partial county estimates are still needed to comply with the CAA requirements for inventories and RFP plans.
2. Source Emission Statements
	States must develop emission reporting programs, called emission statement programs, for VOC and NOx sources in accordance with CAA section 182(a)(3)(B). The required state program and associated regulation defines how states obtain emissions data directly from facilities and report it to the EPA. States should coordinate their emission statement regulations with the requirements laid out in this rule, which includes coordination with requirements of the AERR.
      The EPA published guidance on source emission statements in a July 1992 memorandum titled, "Guidance on the Implementation of an Emission Statement Program." A memorandum titled, "Emission Statement Requirements Under 8-hour Ozone NAAQS Implementation," dated March 14, 2006, clarified that the source emission statement requirement under the CAA was applicable to all areas designated nonattainment for the 1997 ozone NAAQS and classified as Marginal or higher under subpart 2, part D, title I of the CAA. This requirement similarly applies to all areas designated nonattainment for the 2008 ozone NAAQS. Most areas that need an emission statement program already have one in place due to a nonattainment designation for an earlier ozone NAAQS. If an area has a previously approved emission statement rule in force for the 1997 ozone NAAQS or the 1-hour ozone NAAQS that covers all portions of the nonattainment area for the 2008 ozone NAAQS, such rule should be sufficient for purposes of the emissions statement requirement for the 2008 ozone NAAQS. The state should review the existing rule to ensure it is adequate and, if it is, may rely on it to meet the emission statement requirement for the 2008 ozone NAAQS. In cases when an existing emission statement requirement is still adequate to meet the requirements of this rule, states can provide the rationale for that determination to the EPA in a written statement in the SIP to meet this requirement. States should identify the various requirements and how each is met by the existing emission statement program. In cases when an emission statement requirement is modified for any reason, states must provide the revisions to the emission statement as part of their SIP.
K. What are the ambient monitoring requirements?
	The EPA's ambient monitoring requirements are contained in 40 CFR part 58. Monitoring rule amendments published on October 17, 2006, (71 FR 61236) established minimum ozone monitoring requirements based on population and levels of ozone in an area to better prioritize monitoring resources. The minimum monitoring requirements are contained in Table D-2 of Appendix D to part 58. The Photochemical Assessment Monitoring Station (PAMS) program, required by CAA section 182(c)(1), collects enhanced ambient air measurements in ozone nonattainment areas classified as Serious, Severe, or Extreme. The monitoring rule amendments published on October 17, 2006, reduced the minimum PAMS requirements. The revisions were intended to require the retention of the minimum common PAMS network elements necessary to meet the objectives of every PAMS program, while freeing up resources for states to tailor other features of their own PAMS networks to suit their specific data needs. This final rule makes no changes to these existing requirements.
L. How can an area qualify for a 1-year attainment deadline extension?
1. Summary of the Proposal
      Section 181(a)(5) of the CAA addresses the conditions under which an area may be eligible for a 1-year extension of its attainment date. Because that statutory provision was written for an exceedance-based standard, such as the 1-hour ozone NAAQS, the EPA established through the Phase 1 Rule (40 CFR 51.907) an interpretation that would apply to a concentration-based standard, such as the 1997 ozone NAAQS. We proposed the same approach as set forth in section 51.907 for purposes of the 2008 ozone NAAQS, which like the 1997 ozone NAAQS is a concentration-based standard.
2. Final Action
      The EPA is finalizing the proposed approach. An area that fails to attain the 2008 ozone NAAQS by its attainment date would be eligible for the first 1-year extension if, for the attainment year, the area's 4[th] highest daily maximum 8-hour average is at or below the level of the standard. The area would be eligible for the second 1-year extension if the area's 4[th] highest daily maximum 8-hour value, averaged over both the original attainment year and the first extension year, is at or below the level of the standard. Thus, to be eligible for the first 1-year extension, the 4[th] highest daily maximum 8-hour value for an area would need to be at or below 0.075 ppm. The area would be eligible for the second extension if the area's 4th highest daily maximum 8-hour value, averaged over both the original attainment year and the first extension year, is less than or equal to 0.075 ppm.
3. Rationale
	This approach is the same approach used for implementing the 1997 ozone NAAQS. The EPA believes this approach makes sense for the 2008 ozone NAAQS as well.
4. Comments and Responses
	The EPA received no adverse comments on the proposed action.
M. How will the EPA identify rural transport areas?
1. Summary of Proposal
	The CAA Amendments of 1990 contained section 182(h) that provides a "rural transport" determination for ozone nonattainment areas that are rural in nature and can demonstrate that sources in the area do not make a significant contribution to ozone concentrations measured in the area or in other areas. These areas are subject to Marginal nonattainment area requirements, regardless of the area's classification under section 181(a). This classification was created for rural nonattainment areas whose ozone problem is the result of ozone and/or precursors transport into the area that is so overwhelming that the contribution of local emissions to ozone concentrations above the level of the NAAQS is relatively minor and that emissions within the area do not significantly contribute to ozone measured in other areas.
	The criteria in CAA section 182(h) make use of the terms "Metropolitan Statistical Area" (MSA) and "Consolidated Metropolitan Statistical Area" (CMSA) as defined by the U.S. Bureau of the Census. In 2000, OMB issued new standards for defining statistical areas to replace the pre-existing MSA and CMSA definitions (65 FR 82228; December 27, 2000). Under the 2000 standards, MSAs are defined as having a central county or counties with an urbanized area of at least 50,000 people, plus adjacent outlying counties having a high degree of economic integration with the central county, as measured through worker commuting ties. Multiple counties are included in a MSA if at least 25 percent of employed residents in the central county commute to work in one or more adjacent counties. The term CMSA was retired in 2003 with the introduction of Core Based Statistical Area concepts. We proposed to interpret the references to both MSA and CMSA in section 182(h) to refer to the new Census Bureau definition for the term MSA.
2. Final Action and Rationale
	We are finalizing, as proposed, the interpretation of the references to both MSA and CMSA in section 182(h) to refer to OMB's current definition of MSA. Accordingly, to qualify as a rural transport nonattainment area, the nonattainment area's boundary could not include or be adjacent to a current OMB-defined MSA. Under this approach, any nonattainment area associated with a Census-defined micropolitan area (areas with central county or counties containing an urban cluster of 10,000-49,999 people plus adjacent counties having a high degree of economic and social integration as measured through worker commuting) or an area too sparsely populated to be included in a census-defined statistical area, may be able to qualify as a rural transport nonattainment area. An area seeking to be classified as a rural transport nonattainment area would also need to meet the other criteria specified in section 182(h).
      The EPA believes this interpretation of CAA section 182(h) is consistent with the original scope of section 182(h) as promulgated in 1990 and provides maximum flexibility for areas to qualify for this determination where appropriate. We did not receive any adverse comments on our proposed interpretation.
N. What are the special requirements for multi-state nonattainment areas?
      Each state within a multi-state ozone nonattainment area is responsible for meeting all the requirements relevant to that area. Section 182(j)(1)(A) requires that states should "take all reasonable steps to coordinate substantively and procedurally" on SIP development. States should coordinate on topics such as determining the appropriate modeling domain, baseline year, projection years and meteorological episodes. In addition, they should coordinate modeling efforts and, as required by section 182(j)(1)(B), the attainment demonstration must be based on photochemical grid modeling or another method determined by the EPA to be at least as effective.
      Section 182(j)(2) recognizes that in certain instances, one or more states within a multi-state nonattainment area may not submit an attainment plan by the required date, thus interfering with the ability of the area as a whole to demonstrate attainment. In such case, section 182(j) provides that even though the area as a whole would not be able to demonstrate attainment, the sanction provisions of section 179 shall not apply in the portion of the nonattainment area located in a state that submitted all other provisions of an attainment plan and demonstrated that it could have demonstrated attainment but for the failure of the other state to cooperate. The EPA did not propose any changes to its prior interpretations of these sections of the CAA (See 70 FR 71612), and no comments were received on these provisions. Therefore, these interpretations will continue to apply for purposes of the 2008 ozone NAAQS.
O. How will the EPA address interstate and international ozone transport?
1. Interstate Transport
      The EPA recognizes that many states are affected by transported ozone and ozone precursors from upwind states, and that transported pollution may contribute significantly to air pollution that exceeds the NAAQS in those states. The CAA establishes states' responsibilities to address interstate transport through two provisions. First, section 110(a)(2)(D)(i) obligates states to include provisions in their infrastructure SIPs to prohibit any source or other type of emissions activity in one state from contributing significantly to nonattainment, or interfering with maintenance, of the NAAQS in another state, from interfering with required provisions preventing significant deterioration of air quality or from interfering with measures to protect visibility in another state. Second, section 126 directs states to include provisions to establish a notification process in their infrastructure SIPs through which downwind jurisdictions can be alerted to specific sources of transported pollution. The EPA issued its "Guidance on Infrastructure State Implementation Plan Elements Under the Clean Air Act Sections 110(a)(1) and 110(a)(2)," on September 13, 2013, on the required elements of the section 110 infrastructure SIP submittal for the 2008 ozone NAAQS. This guidance does not, however, address the requirements of CAA section 110(a)(2)(D)(i). The proposal for this rulemaking, and this final rule, also do not address these requirements relating to transport. The EPA will address the transport requirements in a separate action.
      Where interstate transported emissions contribute to an exceedance or violation and come from natural sources such as wildfires, air agencies can use the provisions in the EPA's Exceptional Events Rule (40 CFR 50.14) to request exclusion of affected data. Once EPA concurs with an air agency's request, the event-influenced data are officially noted and removed from the data set used to calculate official design values.
      Because of previously expressed stakeholder feedback regarding implementation of the Exceptional Events Rule and specific stakeholder concerns regarding the analyses that can be used to support ozone-related exceptional event demonstrations, the EPA intends to propose revisions to the Exceptional Events Rule in a future notice and comment rulemaking effort and will solicit public comment at that time. Additionally, the EPA intends to develop guidance to address implementing the Exceptional Events Rule criteria for wildfires that could affect ambient ozone concentrations. Depending on the nature and scope of international emission events affecting air quality in the U.S., the EPA may be able to assist states in developing approvable exceptional events demonstrations.
2. International Transport
	Most ozone air quality problems in the United States are due primarily to emission sources within the United States. However, domestic ozone air quality can also be affected by sources of emissions located across United States borders in Canada and Mexico, and from other continents. These contributions to U.S. ozone concentrations from sources outside of the United States can affect to varying degrees the ability of some areas to attain and maintain the 2008 ozone NAAQS. The EPA will continue to work with our domestic and international partners to better understand the extent and implications of transboundary flows of air pollutants and, where possible, to mitigate their impact on U.S. domestic air quality.
a. Summary of the Proposal
	Section 179B of the CAA allows the EPA to approve an attainment demonstration for a nonattainment area if: (1) the attainment demonstration meets all other applicable requirements of the CAA; and (2) the submitting state can satisfactorily demonstrate that "but for emissions emanating from outside of the United States," the area would attain and maintain the ozone standard. The EPA proposed that this could include consideration of any emissions from North American or intercontinental sources.
b. Final Action and Rationale
	The EPA is finalizing this action as proposed. The EPA believes that the best approach for addressing the potential impacts of international transport on nonattainment is for states to work with the relevant EPA Regional Office on a case-by-case basis to determine the most appropriate information and analytical methods for each area's unique situation. We will work with states that are developing plans pursuant to section 179B, and ensure the states have the benefit of the EPA's developing understanding of international transport of ozone and its precursors.
	Although monitored data cannot be excluded for a determination of whether an area has attained a NAAQS based solely on the fact the data are affected by emissions from outside the U.S., such data may be excluded from consideration if they were significantly influenced by exceptional events as described in CAA section 319(b). Where international transport meets the criteria and procedural requirements contained in the EPA's Exceptional Events Rule (40 CFR 50.14), it may be addressed by that rule.
c. Comments and Responses
	Comment: One commenter supported the EPA's interpretation of CAA section 179B to include consideration of any emissions from any non-United States source and requested confirmation that the EPA's interpretation may be applied to areas other than those adjoining international borders. The commenter believed that section 179B does not limit this option to areas, regardless of classification and believed that the EPA did not provide an explanation for why it proposed limiting the availability of a determination under section 179B for Marginal classified areas.
	Response: The EPA appreciates the commenter's support. The EPA has interpreted the Act such that section 179B allows the EPA to approve an attainment demonstration if the state can satisfactorily demonstrate that ``but for emissions emanating from outside of the United States,'' the area would attain and maintain the ozone standard. The EPA has historically evaluated these demonstrations on a case-by-case basis, based on the individual circumstances.  The EPA does not believe this provision is restricted to areas adjoining international borders. Also, in the proposal the EPA indicated that for areas classified as Moderate and above, the modeling and other elements of the attainment demonstration must show timely attainment of the NAAQS but for the emissions from outside of the U.S. However, if a Marginal area (which is not otherwise required to submit an attainment demonstration) were to submit to the EPA a demonstration that they could attain the standard but for international emissions, the EPA would be able to evaluate that demonstration similarly to demonstrations submitted by higher classified areas.
P. How will the section 182(f) NOx provisions be handled?
1. Summary of the Proposal
	We proposed, consistent with the approach taken in the Phase 2 Rule for the 1997 ozone NAAQS and the 2005 updated guidance, that a previously granted NOx exemption (or waiver) under the 1-hour or 1997 ozone NAAQS would not automatically apply for purposes of implementing the 2008 ozone NAAQS.
2. Final Action and Rationale
	We are finalizing this approach as proposed. A state with a previously approved NOx waiver for the 1-hour or 1997 ozone NAAQS would need to submit a new request for an exemption that is supported by analyses specific to the 2008 ozone NAAQS. The new request should consider any relevant information developed after the 1-hour or 1997 8-hour ozone NAAQS waivers were granted.
	The EPA believes that while it may be appropriate in certain circumstances to grant NOx waivers, these waivers should be based upon applications and analyses specifically focused on the circumstances relevant for attainment of the 2008 ozone NAAQS, rather than a previous ozone NAAQS, since the standards for granting a waiver relate to attainment of the relevant NAAQS.
      As states evaluate whether to seek a NOx waiver, the EPA encourages them to include consideration of air quality effects that may extend beyond the designated nonattainment area. A petition requesting a NOx exemption for the 2008 ozone NAAQS must contain adequate documentation that the provisions of section 182(f), some of which relate to attainment impacts in other areas, are met. The January 14, 2005 memo provides guidance on appropriate documentation for a waiver request for application to the 8-hour ozone program. The EPA believes this guidance is sufficient to cover the 2008 ozone NAAQS.
3. Comments and Responses
      Comment: One commenter stated that the EPA should avoid granting NOx exemptions for nonattainment areas that use NOx controls from other programs to demonstrate attainment and/or to address other provisions of the CAA.
      Response: In order to request a NOx exemption, a state must submit a petition specific to the 2008 ozone NAAQS. This petition must specifically address the provisions of section 182(f). The EPA will grant NOx exemptions only through notice- and-comment rulemaking where the public will have an opportunity to address whether the petition complies with the provisions of section 182(f). In granting waivers, the EPA will take into consideration existing NOx controls in an area.
Q. Emissions Reduction Benefits of Energy Efficiency/Renewable Energy Policies and Programs, Land Use Planning and Travel Efficiency
1. Energy Efficiency/Renewable Energy Policies and Programs
      Energy efficiency and renewable energy (EE/RE) policies and programs are adopted by federal, state and local governments to lower energy demand through the use of more energy efficient equipment, technologies and practices and to transition to cleaner energy. These policies help reduce electricity generation from fossil-fueled sources, which, in turn, can result in lower emissions of NOx (as well as other criteria pollutants, hazardous air pollutants and greenhouse gases). Energy efficiency policies offer cost savings benefits, and can be a cost-effective strategy to help achieve air quality goals. The EPA encourages state adoption of these policies and programs to benefit nonattainment areas and to reduce the impact of ozone transport on downwind areas.
      In July 2012, the EPA released the "Roadmap for Incorporating Energy Efficiency/Renewable Energy Policies and Programs into State and Tribal Implementation Plans (SIPs/TIPs)"  to clarify guidance on the incorporation of EE/RE measures in SIPs/TIPs. The Roadmap is a "living" document that will be updated periodically as new information becomes available. The Roadmap describes four pathways that states can use for considering air pollution reductions from EE/RE policies and programs in SIPs and TIPs. Valid EE/RE policies and programs that meet the applicable requirements of section 182(c)(9) can also be used as contingency measures.
	In addition to the Roadmap, the EPA is providing training and technical assistance to state, tribal and local agencies, as well as tools for quantifying the emissions impacts of EE/RE policies and programs (i.e., the AVoided Emissions genERation Tool, AVERT), and energy savings information for state-level EE policies and programs. The EPA is also working with states to develop examples that illustrate how reductions from specific EE/RE policies and programs could be quantified and considered in SIPs.
2. Land Use Planning
      States may also wish to consider strategies that foster more efficient urban and regional development patterns as a long-term air pollution control measure. Resources include the HUD DOT EPA Sustainable Communities Partnership, as well as the policy and technical guidance documents on land use available on the EPA's Office of Transportation and Air Quality website.  These documents provide communities with the information they need to better understand the link between air quality, transportation and land use activities, and how certain land use activities have the potential to help local areas achieve and maintain healthy air quality. The documents also include methods to help communities account for the air quality benefits of their local land use activities in their air quality plans. If wildfire impacts are significant in a particular area, air agencies and communities may be able to lessen the impacts of wildfires by working collaboratively with land managers and land owners to employ various mitigation measures including taking steps to minimize fuel loading in areas vulnerable to fire. The EPA will provide additional guidance as needed, and will continue to work with states on incorporating these types of programs into their SIPs.
3. Travel Efficiency
      Areas may also consider incorporating travel efficiency strategies, such as new or expanded mass transit options, commuter strategies, system operations (e.g., eco-driving, ramp metering), pricing (e.g., parking taxes, congestion pricing, intercity tolls), speed limit restrictions and multimodal freight strategies in their SIPs. In March of 2011, the EPA released two documents that we believe will prove to be useful to states that want to evaluate emissions reductions that may be available from travel efficiency strategies. The first document is titled, "Potential Changes in Emissions Due To Improvements in Travel Efficiency." This report provides information on the effectiveness of travel efficiency measures for reducing emissions of NOx, VOC and PM2.5 at the national scale. The second document is titled, "Transportation Control Measures: An Information Document for Developing and Implementing Emission Reduction Programs." This document provides information on transportation control measures that have been implemented across the country for a variety of purposes, including reducing emissions related to criteria pollutants. These documents are available on the EPA's Office of Transportation and Air Quality website.
R. Efforts to Encourage a Multi-pollutant Approach When Developing 2008 Ozone SIPs
 1. Summary of the Proposal
   The EPA stated in the proposal that from a planning and resource perspective, we believe it can be efficient for states to develop integrated control strategies that address multiple pollutants rather than separate strategies for each pollutant or NAAQS individually. The EPA also provided states with recommendations and considerations to take into account when developing a comprehensive approach. The EPA requested comment on what incentives or assistance we might be able to provide to encourage states to integrate their planning activities.
 2. Final Action and Rationale
       From a planning and resource perspective, the EPA continues to believe that multi-pollutant control strategy planning can be efficient for states. An integrated air quality control strategy that reduces multiple pollutants can help ensure that reductions are efficiently achieved and produce the greatest overall air quality benefits. However, multi-pollutant approaches are not required as part of this rule.
       States may also find it desirable to assess the impact of ozone, PM2.5 and/or regional haze control strategies on toxic air pollutants regulated under the CAA or under state air toxics initiatives. Given the relationships that exist between toxic air pollutants and the formation of ozone and PM2.5, states and sources may find that controls can be selected to meet goals for ozone and/or PM2.5 attainment as well as those of specific toxic air pollutant programs.
      We recommend that states and tribes wishing to take a comprehensive approach consider the following activities:
* Choose or develop models for use in the attainment demonstration that can assess the air quality and ecosystem impacts of measures to reduce ozone precursors, secondary fine particles, pollutants that contribute to regional haze and, where appropriate, toxic air pollutants and other related pollutants that can impact ecosystems.
* Conduct an integrated assessment of the impact controls have on ambient levels of ozone, PM2.5, regional haze and, where applicable, toxic air pollutants, greenhouse gases, ecosystem protection and environmental justice considerations.
* Use common data bases and analytical tools, where possible.
3. Comments and Responses
      Comment: Several commenters supported the use of a multi-pollutant approach. One commenter encouraged the EPA to allow states to take credit for programs that may not yet have been fully implemented. Another commenter noted the constraints in the CAA, which focuses on a pollutant-by-pollutant approach, and another commenter stated that they prefer a single pollutant approach.
      Response: The EPA supports multi-pollutant planning, where possible. Regarding the comment encouraging the EPA to allow states to take credit for programs that may not yet have been fully implemented, please see Section III.B in the preamble for details regarding the EPA's final policy on this subject.
      The EPA also supports considering the co-benefits of emissions reductions on multiple pollutants. We acknowledge that there are CAA constraints that may limit the incentive for multi-pollutant planning, and clarify that single-pollutant planning is acceptable under the Act.
S. What are the requirements for the OTR?
      The EPA proposed to adopt for the 2008 ozone NAAQS the same requirements applicable to the OTR that were codified in 40 CFR 51.916 for the 1997 ozone NAAQS, except that the submission date for OTR RACT SIPs required under section 182(b)(2) would be the same as provided under the RACT section of this regulation for nonattainment areas. (See Section III.A of this preamble for additional information on SIP submittal timeframes.) We are finalizing adoption of the requirements as proposed along with the OTR RACT SIP submittal due date.
T. Are there any additional requirements related to enforcement and compliance?
	The EPA did not propose any specific regulatory provisions related to compliance and enforcement. Section 172(c)(6) requires nonattainment SIPs to "include enforceable emission limitations, and such other control measures, means or techniques ... as well as schedules and timetables for compliance, as may be necessary or appropriate to provide for attainment ..." The EPA's current guidance, "Guidance on Preparing Enforceable Regulations and Compliance Programs for the 15 Percent Rate-of-Progress Plans (EPA-452/R-93-005, June 1993)" is still relevant to rules adopted for SIPs under the 2008 ozone NAAQS and should be consulted for purposes of developing appropriate enforceable nonattainment plan provisions under section 172(c)(6). The EPA did not solicit comment on this section and thus, none were received.
U. What are the requirements for addressing emergency episodes?
1. Summary of the Proposal
	The EPA proposed that the existing requirements for emergency episodes (40 CFR part 51, subpart H) would also apply to the 2008 ozone NAAQS.
2. Final Action and Rationale
      The EPA did not receive any adverse comments on the proposal. The EPA is finalizing the requirements for emergency episodes as proposed. The EPA believes the existing requirements for emergency episodes (40 CFR part 51, subpart H) remain appropriate for the 2008 ozone NAAQS and/or any current ozone NAAQS. If wildfire is a potential contributor to these episodes, the EPA urges implementing state and local agencies to coordinate with the land management agencies, as appropriate, in developing plans and appropriate public communications regarding public safety and reducing exposure.
V. How does the "Clean Data Policy" apply to the 2008 ozone NAAQS?
1. Summary of the Proposal
	The EPA proposed to apply the same approach with respect to the Clean Data Policy for the 2008 ozone NAAQS as it applied in the Phase 1 Rule for the 1997 ozone NAAQS. That is, a determination of attainment would suspend the obligation to submit attainment planning SIP elements for the 2008 ozone NAAQS. Such a determination would suspend the obligation to submit any attainment-related SIP elements not yet approved in the SIP, for so long as the area continues to attain the 2008 ozone NAAQS.
2. Final Action
	The EPA is finalizing this action as proposed. The EPA is replacing 40 CFR 51.918 with 40 CFR 51.1118 to consolidate in one regulation a comprehensive provision applicable to determinations of attainment for the current and former ozone NAAQS. Thus 40 CFR 51.1118 will apply to a determination of attainment that is made with respect to any revoked or current ozone NAAQS  -  the 1-hour, the 1997 or the 2008 ozone NAAQS.
3. Rationale
      The EPA continues to believe that it is appropriate for an area that has met an ozone NAAQS to suspend further attainment planning efforts for that ozone NAAQS. The new section 51.1118 sets forth the regulatory consequences of an EPA determination, made after notice-and-comment rulemaking, that an area designated nonattainment for an ozone standard has air quality attaining that standard. Upon such a determination by the EPA, the requirements for the area to submit an attainment demonstration, associated reasonably available control measures, RFP plans, contingency measures and other attainment-related planning requirements for that NAAQS, shall be suspended until such time as the area is redesignated to attainment, at which time the requirements no longer apply, or until the EPA determines that the area has again violated that ozone NAAQS, in which case the requirements are again applicable.
4. Comments and Responses
	Comment: Several commenters supported the continued use of the Clean Data Policy. One of these commenters requested that the EPA expeditiously redesignate areas using its CAA Section 107(d)(3) authority for states that have submitted "clean data" certification and redesignation/maintenance SIPs.
      Response: As stated in the policy, the requirements for an attainment demonstration, RFP and contingency measures are designed to bring an area into attainment. Once this goal has been achieved, we believe the statute no longer requires submission of plans designed to bring the area into attainment and thus it is appropriate to suspend the obligation that states submit plans to meet that goal, so long as the area continues to attain the relevant standard. The EPA Regional Offices will act on redesignating areas based on any section 175A submittals that were received in as expeditious a manner as possible.
W. How does this final rule apply to tribes?
      As we mentioned in the proposal, tribes are generally not required to submit tribal implementation plans (TIPs). However, should a tribe choose to develop a TIP, this final rule is intended to serve as a guide for addressing key implementation issues for their area of Indian country. This rule will likely be especially useful to those tribes whose areas of Indian country were designated as separate nonattainment areas from surrounding state areas.
X. What collaborative program has the EPA implemented for the 2008 ozone NAAQS?
      The EPA stands ready to assist states in implementing the 2008 ozone NAAQS. The Ozone Advance program, which began in April 2012, is an opportunity for 2008 ozone NAAQS attainment areas to work collaboratively with EPA to improve local air quality. Information on the Ozone Advance program for the 2008 ozone NAAQS is provided in a separate guidance document that is available at http://www.epa.gov/ozonepmadvance.
IV. What are the anti-backsliding requirements for the revoked 1997 ozone NAAQS?
A. What is the effective date of the revocation of the 1997 ozone NAAQS?
1. Summary of the Proposal
	The EPA proposed to exercise its authority to revoke the 1997 ozone NAAQS for all purposes upon the publication of the final SIP Requirements Rule in the Federal Register. The EPA also proposed that anti-backsliding provisions would apply to an area in accordance with its designation and, as applicable, its classification, for the 1997 (and, if applicable, 1-hour) ozone NAAQS at the time of revocation of the 1997 ozone NAAQS. The following sections discuss in detail the applicable anti-backsliding requirements and how they apply to areas with various designations and classifications for the 2008 and the soon to be revoked 1997 and the already revoked 1-hour ozone NAAQS.
2. Final Action
	The EPA is revoking the 1997 ozone NAAQS for all purposes upon the effective date of this final rule, which will be 30 days after publication of this rule in the Federal Register. When the 1997 ozone NAAQS is revoked, the anti-backsliding requirements for that NAAQS, as detailed in this final rulemaking, become applicable. The extent of continued implementation efforts for a revoked standard derives from administration of anti-backsliding requirements for the revoked standard. After the revocation of the 1997 ozone NAAQS, the EPA will no longer be able to take action to reclassify or to redesignate areas for that standard.
	After revocation of the 1997 standard, the designations (and the classifications associated with those designations) for that standard are no longer in effect, and the sole designations that remain in effect are those for the 2008 ozone NAAQS. However, the EPA is retaining the listing of the designated areas for the revoked 1997 ozone NAAQS in 40 CFR part 81, for the sole purpose of identifying the anti-backsliding requirements that may apply to the areas at the time of revocation. Accordingly, such references to historical designations for the revoked standard should not be viewed as current designations under CAA section 107(d).
3. Rationale
      This approach of establishing anti-backsliding requirements is consistent with the EPA's practice in the transition from the 1-hour to the 1997 ozone NAAQS. It is not logical to attach to an area any anti-backsliding requirements for the revoked 1997 NAAQS until that NAAQS is revoked because up until revocation, implementation of the 1997 NAAQS is still adequately governed by the relevant CAA and regulatory provisions, and the EPA can still take actions to redesignate or reclassify areas for that standard.[,] In fact, the status of many areas with respect to designation and classification for the 1997 ozone NAAQS has already changed since promulgation of the 2008 ozone NAAQS. Thus, the EPA concludes that it is reasonable to establish the date of revocation of the 1997 ozone NAAQS as the time for anti-backsliding requirements for that NAAQS to take effect, which is consistent with past practice under the Phase 1 Rule.
      The EPA believes it is appropriate to revoke rather than retain the 1997 ozone NAAQS for all purposes. This final action ensures that only one ozone NAAQS -- the more protective 2008 ozone NAAQS -- directly applies, rather than having two standards apply concurrently. In revoking any standard, the EPA provides adequate anti-backsliding requirements.
      We believe that revoking the 1997 ozone NAAQS is appropriate for all purposes. The EPA believes that the permanent retention of two standards, differing only in the ozone concentrations they allow, creates unnecessary complexity and is not necessary to provide for attainment of the more stringent NAAQS. The EPA's reason for establishing the new standards of 0.075 ppm as requisite to protect public health and welfare was its conclusion that the old standard of 0.08 ppm was not adequate. Revoking (with appropriate anti-backsliding measures) rather than retaining that 1997 ozone NAAQS will facilitate a more seamless transition to demonstrating compliance with the more health and welfare protective 2008 ozone NAAQS. This approach will ensure the most efficient use of state and local resources in working toward attainment of the standard that the EPA has determined is requisite to protect public health and welfare. Moreover, we believe that by requiring adequate anti-backsliding measures we will ensure continued momentum in states' efforts toward achieving cleaner air.
4. Comments and Responses
	Comment: One commenter recognized the EPA's authority to revoke the 1997 ozone NAAQS, but opposed the revocation because attainment of the 1997 NAAQS would advance progress toward the 2008 standard and ensures that such progress would be made sooner rather than later. The commenter indicated that the EPA's proposal to revoke the 1997 ozone NAAQS would waive key requirements for Extreme nonattainment areas under the 1997 standard before the deadline comes due. The commenter also stated that the EPA must explain the specific problems caused by retaining the 1997 (and 1-hour) ozone NAAQS and tailor the solutions to address those specific problems, citing several rulings that the commenter believed that the EPA must provide a rational basis for their action.
	Response: The anti-backsliding approach that the EPA proposed retains all applicable control requirements for the 1997 ozone NAAQS, while enabling areas, where possible, to focus planning efforts on meeting the more protective 2008 ozone NAAQS. We believe the strong anti-backsliding provisions in 40 CFR 51.1105 will ensure that controls already adopted to attain the previous NAAQS continue to be implemented until an area attains the 2008 ozone NAAQS, and will also ensure that there will be no delay in attaining the 1997 ozone NAAQS. Since it is impossible to attain the 2008 ozone NAAQS without also attaining the 1997 ozone NAAQS, retaining the 1997 ozone NAAQS would be largely superfluous from a health protection standpoint.
      The EPA agrees with the commenter that the adopted revocation approach means that the 1997 NAAQS would be revoked before the statutory maximum attainment date for areas classified as Severe and Extreme for the 1997 ozone NAAQS. We believe that Congress understood this possibility when it amended the CAA in 1990 to require the EPA to review each NAAQS every 5 years. Similarly, Congress also recognized that areas with more significant ozone problems would need more time to attain the standard, and gave these areas more time to attain the standard, with timeframes for attainment largely beyond the 5-year timeframe required for review of the NAAQS. The EPA does not agree with the commenter's characterization of revoking the NAAQS, while retaining a retinue of anti-backsliding requirements, as creating perpetual extensions for attaining old standards. The commenter's argument ignores the fact that the old standard has been supplanted by a more protective standard, and that the EPA's anti-backsliding requirements, combined with the CAA's new obligations to achieve the more stringent 2008 ozone NAAQS as expeditiously as practicable, effectively fulfill the function of the prior attainment date. In addition the EPA notes that the attainment demonstration for the prior standard is retained as an anti-backsliding measure.
      The EPA believes that integrating prior requirements with new goals facilitates coherent, effective and timely planning and controls, and minimizes the separate potentially duplicative submittal of requirements left over from obsolete standards. In this time of diminished resources, the states and the EPA need to move forward efficiently without being overburdened by unnecessary paperwork requirements arising from former standards that can detract from efficient movement towards more stringent standards.
      For these reasons, and consistent with the anti-backsliding regime previously endorsed by the D.C. Circuit, South Coast Air Quality Management Dist. v. EPA, 472 F.3d 882  for the transition from the 1-hour to the 1997 ozone NAAQS, the EPA believes that the revocation and associated anti-backsliding measures for the 2008 ozone NAAQS provide the appropriate way to move toward attaining the more protective standards in a timely and effective manner, while ensuring that progress made under previous ozone NAAQS is not lost. For additional details, please refer to the Response to Comments document.
	Comment: A number of commenters in favor of revocation of the 1997 ozone NAAQS suggested alternate dates for revocation. Several commenters wanted an earlier date for revocation, such as the promulgation date of the 2008 ozone NAAQS or the effective date of designations for the 2008 ozone NAAQS. One of these commenters questioned whether the revocation would occur on the date of publication of the rule in the Federal Register or on the effective date of the rule.
	Response: We disagree with commenters that recommended that the EPA revoke the 1997 ozone NAAQS at an earlier date. We believe that revoking the 1997 ozone NAAQS prior to the establishment of clear anti-backsliding requirements would create a gap when taking action on plans submitted by states. The EPA believes and the court has endorsed in South Coast v. EPA, 472 F.3d 882, that backstops to prevent relaxation of measures implemented for a previous NAAQS must be in place before the EPA can revoke that NAAQS. The EPA, upon considering the comment on the effective date of revocation, clarifies here that the 1997 ozone NAAQS will be revoked on the rule's effective date as set forth in the Federal Register. That is, the 1997 ozone NAAQS will be revoked 30 days after publication of the final rule in the Federal Register.
B. What are the applicable requirements for anti-backsliding purposes following the revocation of the 1997 ozone NAAQS?
1. Summary of the Proposal
	The EPA proposal stated that subpart AA, 40 CFR section 51.1100 et seq., would provide comprehensive anti-backsliding requirements for transition to the 2008 ozone NAAQS. The EPA proposed that, upon revocation of the 1997 ozone NAAQS, subpart X, 40 CFR section 51.900 et seq., would be effectively replaced by the proposed subpart AA.
      In  proposed subpart AA, 51.1100(o) specified the list of "applicable requirements" that would apply as anti-backsliding requirements for the transition from the 1997 ozone NAAQS to the 2008 ozone NAAQS. The EPA proposed as "applicable requirements" the requirements that were previously listed in section 51.900(f) (except for Stage II vapor recovery), as well as the addition of three anti-backsliding requirements that were included as a result of the South Coast v. EPA decision: nonattainment NSR thresholds and offset ratios, nonattainment contingency measures for failure to attain by the applicable deadline or to meet RFP milestones, and section 185 fee program requirements. Since the South Coast v. EPA decision, the EPA has been including these three requirements as anti-backsliding requirements for the 1-hour ozone NAAQS for the purpose of discharging its obligations to effectuate anti-backsliding for that standard. The proposed action would formally list them with the other applicable requirements.
      The applicable requirements discussed previously apply to areas that are designated nonattainment for the 2008 ozone NAAQS and remain nonattainment for a previous ozone NAAQS on the date the 1997 ozone NAAQS is revoked. For areas designated attainment for the 2008 ozone NAAQS but nonattainment for the 1997 ozone NAAQS, the EPA proposed that after the 1997 ozone NAAQS is revoked, these areas would not be required to retain in their SIPs nonattainment NSR programs for ozone. Instead, such areas would be required to implement PSD requirements for ozone. The EPA's determination that after revocation of the 1997 ozone NAAQS nonattainment NSR requirements do not apply to areas designated attainment for the 2008 ozone NAAQS is consistent with the Greenbaum v. EPA decision.
      Based on requirements in the Phase 1 rule for the 1997 ozone NAAQS, as modified in light of South Coast v. EPA, the definition of applicable requirements proposed in section 51.1100(o) included the following: 1) RACT; 2) Vehicle I/M programs; 3) Major source applicability cut-offs for purposes of RACT; 4) ROP and/or RFP reductions; 5) the Clean fuels fleet program under section 183(c)(4) of the CAA; 6) Clean fuels for boilers under section 182(e)(3) of the CAA; 7) Transportation control measures during heavy traffic hours as provided under section 182(e)(4) of the CAA; 8) Enhanced (ambient) monitoring under section 182(c)(1) of the CAA; 9) Transportation controls under section 182(c)(5) of the CAA; 10) Vehicle miles traveled provisions under section 182(d)(1)(A) of the CAA; 11) NOx requirements under section 182(f) of the CAA; 12) Attainment demonstrations; 13) Nonattainment contingency measures; 14) Nonattainment NSR requirements; and 15) Section 185 enforcement requirements for Severe and Extreme nonattainment areas for failure to attain.
      As part of the proposal, the EPA indicated that upon revocation of the 1997 ozone NAAQS, the designations for that NAAQS would have no further effect except as references for anti-backsliding purposes. References to the designations for the revoked standard in 40 CFR part 81 would be retained solely for anti-backsliding purposes for areas designated nonattainment for the 2008 ozone NAAQS, and should not be viewed as current nonattainment designations under CAA §107 within the meaning of 40 CFR 51.166(i)(2) and 52.21(i)(2) and, therefore, would not trigger the exemption from PSD requirements otherwise resulting from those provisions. The proposal also requested comment as to whether or not an amendment to 40 CFR 51.166(i)(2) and 52.21(i)(2) would be appropriate to make it clear that a nonattainment designation for a revoked NAAQS, once the revocation becomes effective in an area, would not trigger the PSD exemption in those provisions and would not prevent application of PSD requirements for that pollutant and how to word such an amendment. Alternatively, the EPA sought comment as to whether it would be sufficient for the EPA to articulate the interpretation of these provisions as described earlier in this paragraph.
2. Final Action
	The EPA is finalizing the anti-backsliding requirements as proposed, including amendments to 51.166(i)(2) and 52.21(i)(2) which address classifications for revoked NAAQS. The amended subpart AA addresses anti-backsliding requirements for both the previously revoked 1-hour ozone NAAQS and the 1997 ozone NAAQS in a consolidated and streamlined fashion. Areas designated nonattainment for the 2008 ozone NAAQS and also designated nonattainment for the 1997 ozone NAAQS at the time of revocation of the 1997 ozone NAAQS will be subject to section 51.1100(o). As proposed, areas designated attainment for the 2008 ozone NAAQS and nonattainment for the 1997 ozone NAAQS when the 1997 ozone NAAQS is revoked will become subject to PSD requirements rather than nonattainment NSR requirements once the revocation is effective.
	Also as proposed, three items are being added to the list of applicable requirements: nonattainment contingency measures, nonattainment NSR requirements (clarified to refer to major source thresholds and offset ratios), and section 185 requirements for Severe and Extreme areas. As proposed, Stage II vapor recovery is not being included in the list of applicable requirements for the reasons described above.
	Based on feedback received during the comment period, the EPA is specifically including two additional items in the list of applicable requirements: RACM and section 182(e)(5) contingency measures. These provisions were implicitly included in the attainment demonstration but are listed separately for clarification. As such, the complete list of applicable requirements in section 51.1100(o) is: 1) RACT; 2) Vehicle I/M programs; 3) Major source applicability cut-offs for purposes of RACT; 4) ROP and/or RFP reductions; 5) the Clean fuels fleet program under section 183(c)(4) of the CAA; 6) Clean fuels for boilers under section 182(e)(3) of the CAA; 7) Transportation control measures during heavy traffic hours as provided under section 182(e)(4) of the CAA; 8) Enhanced (ambient) monitoring under section 182(c)(1) of the CAA; 9) Transportation controls under section 182(c)(5) of the CAA; 10) Vehicle miles traveled provisions under section 182(d)(1)(A) of the CAA; 11) NOx requirements under section 182(f) of the CAA; 12) Attainment demonstrations; 13) Nonattainment contingency measures; 14) Nonattainment NSR major source thresholds and offset ratios; 15) Section 185 requirements for Severe and Extreme areas for failure to attain; 16) RACM; and 17) Contingency measures for SIPs invoking section 182(e)(5) of the CAA.
3. Rationale
	As detailed in the proposal, the EPA already treats nonattainment contingency measures, nonattainment NSR major source thresholds and offset ratios, and section 185 requirements for Severe and Extreme areas as being included in the list of applicable requirements that apply to areas for anti-backsliding purposes under the revoked 1-hour NAAQS, consistent with the South Coast v. EPA decision. Their explicit inclusion in this list is to formalize their place in the list of applicable requirements. Similarly, Stage II vapor recovery is not included in this list due to the May 16, 2012 determination that the requirement is waived, and that an area currently implementing a Stage II control program can, under certain circumstances, remove it from the SIP. These changes to the list of applicable requirements reflect policies already being implemented by the EPA.
	Similarly, areas designated attainment for the 2008 ozone NAAQS and nonattainment for the 1997 ozone NAAQS when the 1997 ozone NAAQS is revoked will become subject to PSD rather than nonattainment NSR once the revocation takes effect. An area that is attainment for the 2008 ozone NAAQS is attaining the most current and health protective ozone standard. The EPA believes that Congress did not intend to hold such an area to the requirements for an old standard when the area has met a newer, more stringent standard of the same form. Such areas will implement PSD for the 2008 ozone NAAQS once the revocation of the 1997 ozone NAAQS takes effect, notwithstanding any remaining references to nonattainment designations for the 1997 ozone NAAQS in 40 CFR part 81. The references to the designations for the revoked standard in 40 CFR part 81 are retained solely for anti-backsliding purposes for areas designated nonattainment for the 2008 ozone NAAQS. Accordingly, such references to historical nonattainment designations for the revoked standard should not be viewed as current nonattainment designations under CAA § 107 within the meaning of 40 CFR 51.166(i)(2) and 52.21(i)(2) and, therefore, do not trigger the exemption from PSD requirements otherwise resulting from those provisions.
	Upon reviewing comments, the EPA decided that sufficient arguments were provided to append two additional items to the list of applicable requirements in 51.1100(o). Those two items are RACM and 182(e)(5) contingency measures. The EPA views this as a clarification, rather than as an addition of control elements. Attainment demonstration SIPs are already listed as an applicable requirement. RACM is an integral part of an approvable attainment demonstration. Similarly, contingency measures will become a required element of 51.1100(o) consistent with the South Coast v. EPA decision. Adding contingency measures associated with section 182(e)(5) to the list is a clarification, rather than an imposition of an additional requirement.
4. Comments and Responses
	Comment: A commenter pointed out that, with regard to applicable requirements, federal measures and locally implemented measures are held to two separate standards. The commenter used the example of Stage II vapor recovery. The EPA removed Stage II vapor recovery from the list of applicable requirements. However, locally implemented control measures included in a SIP for a previous NAAQS must be retained in perpetuity.
	Response: The EPA disagrees with the commenter. SIP-approved control measures, whether federal programs or locally implemented measures, may not be modified unless the modification meets the requirements of CAA section 110(l) and, if applicable, section 193. For purposes of anti-backsliding, Stage II control programs are no longer mandatory because the EPA has determined under the statutory provisions of section 202(a)(6) that another federal program, onboard refueling vapor recovery (ORVR) technology, is in widespread use, rendering Stage II controls largely redundant. However, in an area where a Stage II control program is already adopted into the SIP, it cannot be removed from the SIP unless the conditions of CAA sections 110(l) and 193 are met. Therefore, it is subject to the same treatment as any locally implemented SIP-adopted control measure.
	Comment: A commenter stated that no planning requirements from the 1997 ozone NAAQS should apply once that NAAQS is revoked. The commenter based this on two arguments. First, CAA section 172(e) applies to control requirements and not state planning requirements. Second, the commenter argued that the decision in South Coast v. EPA has limited applicability because the court was faced with two ozone standards that differed in form and level, and in this situation the two standards are of the same form.
	Response: The EPA agrees that the transition from the 1997 ozone NAAQS to the 2008 ozone NAAQS calls for a re-evaluation of the provisions necessary to protect against backsliding and ensure continued progress toward achieving healthy air quality. However, we do not agree that South Coast v. EPA has limited application to informing appropriate anti-backsliding requirements for a revoked 1997 NAAQS simply because the 2008 NAAQS has the same form as the 1997 NAAQS. With only one exception, the seventeen "applicable requirements" that will be listed in new 40 CFR 51.1100(o) are all control requirements, consistent with South Coast v. EPA. To the extent that any of these control requirements have not been implemented in a 1997 nonattainment area by the time the 1997 NAAQS is revoked, consistent with South Coast v. EPA the state must ensure these controls are adopted into the SIP and implemented, if applicable. The one applicable requirement that involves both planning and control elements is the attainment demonstration requirement. Since the attainment demonstration is part of the basis for establishing that the RACM requirement (a control requirement consistent with South Coast) is satisfied, the EPA believes it is appropriate to retain this as an applicable anti-backsliding requirement to ensure timely progress toward attainment of the 1997 NAAQS, especially for areas classified in the highest classifications where the statutory attainment dates for the 1997 NAAQS extend well into the future (e.g., 2019 for Severe and 2024 for Extreme areas). The EPA encourages states to synchronize their planning and emissions control efforts for attainment of the 2008 ozone NAAQS with any unfulfilled anti-backsliding requirements associated with the revoked 1997 ozone NAAQS. As a reminder, a Clean Data Determination for the 1997 ozone NAAQS can suspend the associated attainment demonstration requirement for as long as the area continues to attain the 1997 NAAQS.
	Comment: A commenter pointed out that there are several control measures that continue to apply to areas after a standard is revoked. The commenter argued that, for consistency, the EPA should include these items in the list of applicable requirements. For example, RACT is listed as an applicable requirement, but not RACM. The commenter argued that RACM should be listed as an applicable requirement. Similarly, transportation conformity, "other control measures" as necessary for attainment under CAA section 172(c)(6), and contingency measures for CAA section 182(e)(5) measures should be retained as applicable requirements, according to the commenter.
	Response: The EPA agrees in part with the commenter, that it is appropriate to list both RACM and section 182(e)(5) contingency measures as "applicable requirements" in the final rule in section 51.1100(o). RACM is a component of the attainment demonstration and is a requirement of the CAA. The EPA reviews each SIP submission from a state to ensure that sufficient information is provided for the EPA to determine whether the state has adopted all RACM necessary for attainment as expeditiously as practicable and provided for implementation of those measures as expeditiously as practicable. For areas remaining in nonattainment for the 1997 ozone NAAQS and designated nonattainment for the 2008 ozone NAAQS, the EPA does not believe that revocation of the NAAQS should halt or delay the planned implementation of control measures. These measures, while adopted pursuant to the 1997 ozone NAAQS, will also assist the areas in attaining the 2008 ozone NAAQS.
      Similarly, for Extreme areas relying on CAA section 182(e)(5), the EPA agrees that the contingency measures required for that program should be held to the same requirements as contingency measures for sections 172(c) and 182(c) of the CAA. Thus the EPA is adding 182(e)(5) contingency measures to the list of applicable requirements in 51.1100(o).
However, the EPA does not agree with the commenter that conformity needs to be retained as an applicable requirement. Transportation and general conformity are retained as requirements for all areas designated nonattainment for the 2008 ozone NAAQS. For areas designated attainment for the 2008 ozone NAAQS, these areas are meeting the most stringent, health-protective NAAQS and thus have no remaining conformity requirements because they are designated attainment for the 2008 ozone NAAQS and the designations for the 1997 ozone NAAQS which trigger conformity requirements are revoked. Transportation and general conformity apply only in areas designated as nonattainment or redesignated to attainment with an approved CAA section 175A maintenance plan. (CAA section 176(c)(5)). Upon the effective date of the revocation of the 1997 ozone NAAQS the only relevant designation for ozone for conformity purposes will be an area's designation for the 2008 ozone NAAQS. Areas that are designated attainment for the 2008 ozone NAAQS are not subject to transportation or general conformity requirements regardless of their designation for the 1997 ozone NAAQS at the time of revocation of that NAAQS. (CAA section 176(c)(5)). Similarly, "other control measures" necessary for attainment are already covered by the attainment demonstration, and cannot be removed without satisfying CAA section 110(l).
	Comment: A commenter disagreed with what it described as the EPA's proposal to allow areas that were designated nonattainment for the 1997 ozone NAAQS or the 1-hour NAAQS before those standards were revoked to terminate any nonattainment NSR or 185 fee requirements once the 1997 ozone NAAQS is revoked and the area has been designated or redesignated attainment for the 2008 ozone NAAQS or a redesignation substitute has been approved for the revoked standard. The commenter argues that allowing such an area to remove nonattainment NSR or 185 fee requirements from the SIP is contrary to the NRDC v. EPA ruling.
	Response: The court ruled in NRDC v. EPA that it would be improper for the EPA to relieve an area that has not attained a standard from requirements imposed for failure to attain that standard. The EPA's "redesignation substitute" proposal does not do that. It relieves areas that demonstrate that they are in fact attaining a standard from obligations arising from failure to attain that standard as well as all anti-backsliding requirements applicable for any prior revoked standard without the need for a formal redesignation. Nothing in the 2009 NRDC v. EPA decision  forecloses that approach. The EPA also rejects any suggestion that an area would remain subject to NSR or 185 fees after it is designated as an attainment area and any prior standards for which it was designated nonattainment have been revoked. Areas cannot be redesignated to attainment for ozone unless they have attained all current standards and met all anti-backsliding requirements applicable for prior revoked standards. Moreover, nonattainment NSR is not a requirement in attainment areas and 185 by its own terms does not apply to an area that has been designated "an attainment area for ozone."
C. Application of Transition Requirements to Nonattainment and Attainment Areas
	This section discusses how the transition requirements apply to various types of areas. The general principle is to apply transition requirements depending on how the area is designated  -  attainment or nonattainment  -  for the 2008 ozone NAAQS, while taking into account the area's status with respect to prior standards. In the subsequent sections, for purposes of determining an area's transition requirements, we first look to the area's designation and classification for the 2008 ozone NAAQS. We then determine the area's designation and classification status for the 1997 ozone NAAQS as of the effective date the 1997 ozone NAAQS is revoked. Finally, where appropriate, we determine whether anti-backsliding requirements for the 1-hour ozone NAAQS apply in the area and, if so, we determine the area's designation and classification status for the 1-hour ozone NAAQS as of the date the 1-hour NAAQS was revoked. Appendix B of this rule contains a list of areas subject to anti-backsliding requirements.
1. Requirements for Areas Designated Attainment for the 2008 Ozone NAAQS and Maintenance for the 1997 Ozone NAAQS
a. Summary of the Proposal
	For this category, the EPA proposed that an area's approved section 175A maintenance plan for the revoked 1997 ozone NAAQS satisfies both its obligations for maintenance under section 110(a)(1) for the 2008 ozone NAAQS and its obligation to submit a second approvable maintenance plan under section 175A for the revoked 1997 ozone NAAQS.
b. Final Action
	The EPA is finalizing this as proposed. For areas designated attainment for the 2008 ozone NAAQS and maintenance for the 1997 ozone NAAQS (as of the date of revocation of the 1997 ozone NAAQS), the area's approved section 175A maintenance plan for the revoked 1997 ozone NAAQS satisfies both its obligations for maintenance under section 110(a)(1) for the 2008 ozone NAAQS and its obligation to submit a second approvable maintenance plan under section 175A for the revoked 1997 ozone NAAQS.
c. Rationale
	All areas in this category were already subject to a section 175A maintenance plan for the revoked 1997 ozone NAAQS, and have been both redesignated to attainment for the 1997 ozone NAAQS (as well as any other revoked ozone NAAQS) and designated attainment for the more stringent 2008 ozone NAAQS. The approved section 175A maintenance plan for the 1997 ozone NAAQS satisfied the anti-backsliding requirements of these areas for the prior 1-hour NAAQS. Any further 110(a)(1) maintenance plan requirement under the 2008 ozone NAAQS would be unnecessarily burdensome. No revision to the section 175A maintenance plans for these areas can be approved unless it complies with the anti-backsliding checks in CAA sections 110(l) and 193. The EPA believes that there is no justification for additional maintenance plan demonstration burdens to be imposed on these areas solely because at one time they were designated nonattainment under the revoked 1997 ozone NAAQS. This approach recognizes and reflects that these areas were redesignated to attainment for the 1997 ozone NAAQS prior to its revocation, and have been designated attainment for the 2008 ozone NAAQS.
d. Comments and Responses
	Comment: One commenter opposed this action for several reasons. First, the commenter stated that the EPA cannot dispense with the statutory responsibility of areas by excusing compliance with CAA section 110(a)(1). Second, the commenter believes that demonstrating long-term compliance via an approved 175A maintenance plan for the 1997 ozone NAAQS is not sufficient to demonstrate continued compliance with the 2008 ozone NAAQS. The commenter maintained that even with an approved 175A plan for the 1997 ozone NAAQS, emissions can continue to increase. There is nothing in the approved 175A plan that will be activated should the area start to violate the 2008 ozone NAAQS.
      Response: The EPA disagrees with the commenter. The EPA is not ignoring the maintenance provision of section 110(a)(1), but rather evaluating what is sufficient to address that provision under the circumstances of transition to a new more stringent NAAQS for an area designated attainment for that more stringent NAAQS. With the control measures included in their SIPs and in approved section 175A maintenance plans, those areas have already achieved sufficient emissions reductions to bring them into attainment for both the 1997 ozone NAAQS and the more stringent 2008 ozone NAAQS. These SIP control measures cannot be weakened without satisfying section 110(l) and in some cases also section 193, which effectively serve as anti-backsliding provisions. The EPA is not relieving areas designated attainment of the requirement under section 110(a)(1) to maintain the more stringent 2008 ozone NAAQS, but rather, the EPA is allowing the approved PSD plan for the 2008 ozone NAAQS to suffice as a maintenance showing for these areas. These are areas that already have many controls in place, including approved section 175A maintenance plans ensuring that the areas can maintain the level of the prior standard.
      While these approved 175A maintenance plans were established for maintenance of the 1997 ozone NAAQS, and accordingly help prevent backsliding for that revoked NAAQS, they also provide a foundation for maintenance of the 2008 ozone NAAQS, which, in combination with other active requirements for the 2008 ozone NAAQS, contribute to maintenance of the new standard. The emissions reductions for one NAAQS build upon the emissions reductions from previous NAAQS. The EPA concludes that no additional measures beyond the prior 175A maintenance plans and the PSD plans for the 2008 standard should be necessary to provide for maintenance in these areas. The EPA will work with states as necessary to address any future air quality concerns and maintenance needs for these areas.
2. Areas Designated Attainment for the 2008 Ozone NAAQS and Nonattainment for the 1997 Ozone NAAQS
a. Summary of the Proposal
      The EPA proposed two approaches for this category. The EPA proposed as its preferred approach for areas designated attainment for the 2008 ozone NAAQS and nonattainment for the 1997 ozone NAAQS (as of revocation of the 1997 ozone NAAQS) that the state not be required to adopt any outstanding applicable requirements for the area for the revoked 1997 standard. This approach was similar to the approach followed in the Phase 1 Rule. The EPA also proposed, in a departure from the Phase 1 Rule, that the approved PSD SIPs for these areas satisfy the obligation to submit an approvable maintenance plan for the 2008 ozone NAAQS under section 110(a)(1).
      The second, and less preferred, alternative proposed by the EPA for these areas was that the state be required to demonstrate maintenance for the 2008 ozone NAAQS via a "maintenance showing." This maintenance showing would be due 3 years after the effective date of designations for the 2008 ozone NAAQS and would be in a form other than a formal SIP revision. The maintenance showing would contain a demonstration of continued maintenance of the 2008 ozone NAAQS in the area for 10 years from the effective date of the area's designation as attainment for the 2008 ozone NAAQS. The EPA committed to providing guidance regarding the specific elements of the maintenance showing if this route were chosen.
b. Final Action
	The EPA is finalizing the preferred option: for areas designated attainment for the 2008 ozone NAAQS and nonattainment for the 1997 ozone NAAQS (as of revocation of the 1997 ozone NAAQS) states are not required to adopt any outstanding applicable requirements for the revoked 1997 standard. Approved PSD SIPs for these areas satisfy the obligation to submit an approvable maintenance plan for the 2008 ozone NAAQS under section 110(a)(1).
c. Rationale