EPA Proposes Cleveland OH Ozone Attainment Redesignation

Proposed Rule

Air Plan Approval; Ohio; Redesignation of the Cleveland, OH Area to Attainment of the 2015 Ozone Standards

A Proposed Rule by the Environmental Protection Agency on 04/10/2026

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• Public Inspection Published Document: 2026-06943 (91 FR 18355) Document Headings ###### Environmental Protection Agency

1. 40 CFR Parts 52 and 81
2. [EPA-R05-OAR-2025-3654; FRL-13297-01-R5]

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Proposed rule.

SUMMARY:

The Environmental Protection Agency (EPA) is proposing to act in accordance with a request from the Ohio Environmental Protection Agency (Ohio EPA) to redesignate the Cleveland, Ohio area to attainment for the 2015 ozone National Ambient Air Quality Standards (NAAQS) because the request meets the statutory requirements for redesignation under the Clean Air Act (CAA). The Cleveland area includes Cuyahoga, Geauga, Lake, Lorain, Medina, Portage, and Summit Counties. Ohio EPA submitted this request on December 8, 2025. The EPA is also proposing to approve, as a revision to the Ohio State Implementation Plan (SIP), the State's plan for maintaining the 2015 ozone NAAQS through 2038 in the Cleveland area. The EPA is also initiating the adequacy process and proposing to approve Ohio's 2032 and 2038 volatile organic compound (VOC) and oxides of nitrogen (NO X) motor vehicle emissions budgets (budgets) for the Cleveland area. Additionally, the EPA is proposing to adjust the deadline for Ohio to submit Serious SIP revisions for the Cleveland area. Finally, the EPA is proposing to approve the Enhanced motor vehicle inspection and maintenance (I/M) program certification, clean fuel vehicle program (CFVP) certification, and enhanced monitoring plan (EMP) certification SIP revisions submitted by Ohio EPA on December 19, 2025, and January 12, 2026, pursuant to section 110 and part D of the CAA, because they satisfy Serious SIP requirements for the Cleveland area under the 2015 ozone NAAQS.

DATES:

Comments must be received on or before May 11, 2026.

ADDRESSES:

Submit your comments, identified by Docket ID No. EPA-R05-OAR-2025-3654 at https://www.regulations.gov, or via email to arra.sarah@epa.gov. For comments submitted at Regulations.gov, follow the online instructions for submitting comments. Once submitted, comments cannot be edited or removed from the docket. The EPA may publish any comment received to its public docket. Do not submit to the EPA's docket at https://www.regulations.gov any information you consider to be Confidential Business Information (CBI), Proprietary Business Information (PBI), or other information whose disclosure is restricted by statute. Multimedia submissions (audio, video, etc.) must be accompanied by a written comment. The written comment is considered the official comment and should include discussion of all points you wish to make. The EPA will generally not consider comments or comment contents located outside of the primary submission (i.e. on the web, cloud, or other file sharing system). For additional submission methods, please contact the person identified in the FOR FURTHER INFORMATION CONTACT section. For the full EPA public comment policy, information about CBI, PBI, or multimedia submissions, and general guidance on making effective comments, please visit https://www.epa.gov/​dockets/​commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT:

Cecilia Magos, Air and Radiation Division (AR18J), Environmental Protection Agency, Region 5, 77 West Jackson Boulevard, Chicago, Illinois 60604, telephone number: (312) 886-7336, email address: magos.cecilia@epa.gov.

SUPPLEMENTARY INFORMATION:

Throughout this document whenever “we,” “us,” or “our” is used, we mean the EPA. This supplementary information section is arranged as follows:

I. What is the EPA proposing?

II. What is the background for these actions?

III. What are the criteria for redesignation?

IV. What is the EPA's analysis of Ohio's redesignation request?

V. Has the State adopted approvable motor vehicle emission budgets?

VI. Adjustment of SIP Submittal Deadlines

VII. Enhanced I/M

VIII. Clean Fuel Vehicle Program

IX. Enhanced Monitoring Program

X. What action is the EPA taking?

XI. Statutory and Executive Order Reviews

I. What is the EPA proposing?

The EPA is proposing to take several related actions. The EPA proposes to determine that the Cleveland area has met the requirements for redesignation under section 107(d)(3)(E) of the CAA, and the EPA is thus proposing to change the legal designation of the Cleveland area from nonattainment to attainment for the 2015 ozone NAAQS. The EPA is also proposing to approve, as a revision to the Ohio SIP, the State's maintenance ( printed page 18356) plan for the area (such approval being one of the CAA criteria for redesignation to attainment status). The maintenance plan is designed to keep the Cleveland area in attainment of the 2015 ozone NAAQS through 2038. As a part of the maintenance plan, the EPA is initiating the adequacy process and proposing to approve the newly established 2032 and 2038 motor vehicle emissions budgets for the Cleveland area. Additionally, the EPA is proposing to adjust the deadline for Ohio to submit Serious SIP revisions for the Cleveland area to no later than December 5, 2026. Finally, the EPA is also proposing to approve several elements which meet section 110 and part D of the CAA and the EPA's regulations for an area which is classified as Serious nonattainment for the 2015 ozone NAAQS. These elements include Enhanced I/M certification, CFVP certification, and EMP certification SIP revisions submitted by Ohio EPA on December 19, 2025, and supplemented on January 12, 2026.

II. What is the background for these actions?

The EPA has determined that ground-level ozone is detrimental to human health. On October 1, 2015, the EPA promulgated a revised 8-hour ozone NAAQS of 0.070 parts per million (ppm). See 80 FR 65292 (October 26, 2015). Under the EPA's regulations at 40 CFR part 50, the 2015 ozone NAAQS is attained in an area when the 3-year average of the annual fourth highest daily maximum 8-hour average concentration is equal to or less than 0.070 ppm, when truncated after the thousandth decimal place, at all of the ozone monitoring sites in the area. See 40 CFR 50.19 and appendix U to 40 CFR part 50.

Upon promulgation of a new or revised NAAQS, section 107(d)(1)(B) of the CAA requires the EPA to designate as nonattainment any areas that are violating the NAAQS, based on the most recent three years of quality assured ozone monitoring data. The Cleveland area was designated as a Marginal nonattainment area for the 2015 ozone NAAQS on June 4, 2018 (83 FR 25776) (effective August 3, 2018). On October 7, 2022 (87 FR 60897), the EPA determined that the Cleveland area did not attain the standards by the Marginal attainment date, and the area was reclassified as Moderate by operation of law. More recently, on December 17, 2024 (89 FR 101901), the EPA determined the area did not attain the standards by the Moderate attainment date, and the area was reclassified as Serious by operation of law. The EPA established Serious area SIP submission deadlines by rule at 40 CFR 51.1402(b)(1)(i). This set January 1, 2026, as the Serious area SIP submission deadline applicable to the Cleveland area. As noted in that regulatory provision, the default deadline for reclassified areas applies “unless the Administrator establishes a different deadline in a separate action.”

III. What are the criteria for redesignation?

Section 107(d)(3)(E) of the CAA allows redesignation of an area to attainment of the NAAQS provided that: (1) the Administrator (EPA) determines that the area has attained the NAAQS; (2) the Administrator has fully approved the applicable implementation plan for the area under section 110(k) of the CAA; (3) the Administrator determines that the improvement in air quality is due to permanent and enforceable reductions in emissions resulting from implementation of the applicable SIP, applicable Federal air pollutant control regulations, and other permanent and enforceable emission reductions; (4) the Administrator has fully approved a maintenance plan for the area as meeting the requirements of section 175A of the CAA; and (5) the State containing the area has met all requirements applicable to the area for the purposes of redesignation under section 110 and part D of the CAA.

On April 16, 1992 (57 FR 13498), the EPA provided guidance on redesignations in the General Preamble for the Implementation of title I of the CAA Amendments of 1990 and supplemented this guidance on April 28, 1992 (57 FR 18070). The EPA has provided further guidance on processing redesignation requests in policy memoranda, including the September 4, 1992, memorandum from John Calcagni, Director, Air Quality Management Division, entitled “Procedures for Processing Requests to Redesignate Areas to Attainment,” (Calcagni Memorandum).

IV. What is the EPA's analysis of Ohio's redesignation request?

A. Has the Cleveland area attained the 2015 ozone NAAQS?

For redesignation of a nonattainment area to attainment, the CAA requires the EPA to determine that the area has attained the applicable NAAQS (CAA section 107(d)(3)(E)(i)). An area is attaining the 2015 ozone NAAQS if it meets the 2015 ozone NAAQS, as determined in accordance with 40 CFR 50.19 and appendix U of part 50, based on three complete, consecutive calendar years of quality-assured air quality data for all monitoring sites in the area. To attain the 2015 ozone NAAQS, the 3-year average of the annual fourth-highest daily maximum 8-hour average ozone concentrations (ozone design values) at each monitor must not exceed 0.070 ppm. The air quality data must be collected and quality-assured in accordance with 40 CFR part 58 and recorded in the EPA's Air Quality System (AQS). Ambient air quality monitoring data for the 3-year period must also meet data completeness requirements. An ozone design value is valid if daily maximum 8-hour average concentrations are available for at least 90% of the days within the ozone monitoring seasons, [1 ] on average, for the 3-year period, with a minimum data completeness of 75% during the ozone monitoring season of any year during the 3-year period. See section 4 of appendix U to 40 CFR part 50.

On February 27, 2026 (91 FR 9800), the EPA proposed to determine that the Cleveland area attained the 2015 ozone NAAQS based on ozone monitoring data for the 2023-2025 period and to suspend certain planning requirements related to the attainment of the NAAQS (clean data determination or CDD). A summary of the monitoring data relied upon in that proposal is presented in Table 1. These data demonstrate that the Cleveland area is attaining the 2015 ozone NAAQS. ( printed page 18357)

| County | Monitor | 2023 4th high (ppm) | 2024 4th high (ppm) | 2025 4th high (ppm) | 2023-2025
average (ppm) |
| --- | --- | --- | --- | --- | --- |
| Cuyahoga | 39-035-0034 | 0.068 | 0.072 | 0.070 | 0.070 |
| | 39-035-0060 | 0.062 | 0.065 | 0.068 | 0.065 |
| | 39-035-0064 | 0.075 | 0.065 | 0.068 | 0.069 |
| Geauga | 39-055-0004 | 0.066 | 0.066 | 0.069 | 0.067 |
| Lake | 39-085-0003 | 0.069 | 0.071 | 0.071 | 0.070 |
| | 39-085-0007 | 0.070 | 0.069 | 0.070 | 0.069 |
| Lorain | 39-093-0018 | 0.064 | 0.061 | 0.066 | 0.063 |
| Medina | 39-103-0004 | 0.072 | 0.065 | 0.068 | 0.068 |
| Portage | 39-133-1001 | 0.070 | 0.067 | 0.070 | 0.069 |
| Summit | 39-153-0026 | 0.071 | 0.069 | 0.066 | 0.068 |
The Cleveland area's 3-year ozone design value for 2023-2025 is 0.070 ppm, [2 ] which meets the 2015 ozone NAAQS.

The EPA will not take final action to redesignate the Cleveland area to attainment if the EPA fails to finalize the CDD or if the design value of a monitoring site in the area violates the NAAQS prior to final approval of the redesignation. As discussed in section IV.D.3. below, Ohio EPA has committed to continue monitoring ozone in this area to verify maintenance of the 2015 ozone NAAQS.

B. Has Ohio met all applicable requirements of section 110 and part D of the CAA for the Cleveland area, and does Ohio have a fully approved SIP for the area under section 110(k) of the CAA?

For redesignation of an area from nonattainment to attainment of a NAAQS, the CAA requires the EPA to determine that the State has met all applicable requirements under section 110 and part D of title I of the CAA (see section 107(d)(3)(E)(v) of the CAA) and that the State has a fully approved SIP under section 110(k) of the CAA (see section 107(d)(3)(E)(ii) of the CAA). The EPA proposes to find that Ohio has met all applicable SIP requirements for purposes of redesignation under section 110 and part D of title I of the CAA (requirements specific to nonattainment areas for the 2015 ozone NAAQS). In separate actions, the EPA is proposing approval of Ohio's source specific VOC and NO X RACT determinations for sources at or above the Moderate major source threshold. Recognizing that these SIP elements must be approved on or before the date the EPA completes final rulemaking redesignating the area, the EPA proposes to determine that, providing this occurs, the EPA will have fully approved Ohio's SIP under section 110(k) of the CAA. In making these proposed determinations, the EPA ascertained which requirements are applicable for purposes of redesignation, and whether the required Ohio SIP elements are fully approved under section 110(k) and part D of the CAA. As discussed more fully below, SIPs must be fully approved only with respect to these applicable requirements of the CAA.

The EPA proposed in its CDD action to determine that the Cleveland area has attained the 2015 standard, under 40 CFR 51.1318. Providing that determination is finalized, the requirements to submit certain planning SIPs related to attainment, including attainment demonstration requirements (the reasonably available control measures (RACM) requirement of section 172(c)(1) of the CAA, the reasonable further progress (RFP) and attainment demonstration requirements of sections 172(c)(2) and (6) and 182(b)(1) of the CAA, and the requirement for contingency measures of section 172(c)(9) of the CAA) would not be applicable to the area as long as it continues to attain the NAAQS and would cease to apply upon redesignation. In addition, in the context of redesignations, the EPA has interpreted requirements related to attainment as not applicable for purposes of redesignation. For example, in the General Preamble, the EPA stated that:

“The section 172(c)(9) requirements are directed at ensuring RFP and attainment by the applicable date. These requirements no longer apply when an area has attained the standard and is eligible for redesignation. Furthermore, section 175A for maintenance plans provides specific requirements for contingency measures that effectively supersede the requirements of section 172(c)(9) for these areas.” (General Preamble, 57 FR 13498 at 13564, April 16, 1992).

See also Calcagni Memorandum at 6 (“The requirements for reasonable further progress and other measures needed for attainment will not apply for redesignations because they only have meaning for areas not attaining the standard”).

1. Ohio has met all applicable requirements of section 110 and part D of the CAA applicable to the Cleveland area for purposes of redesignation.

a. Section 110 General Requirements for Implementation Plans

Section 110(a)(2) of the CAA delineates the general requirements for a SIP. Section 110(a)(2) provides that the SIP must have been adopted by the State after reasonable public notice and hearing, and that, among other things, it must: (1) include enforceable emission limitations and other control measures, means or techniques necessary to meet the requirements of the CAA; (2) provide for establishment and operation of appropriate devices, methods, systems and procedures necessary to monitor ambient air quality; (3) provide for implementation of a source permit program to regulate the modification and construction of stationary sources within the areas covered by the plan; (4) include provisions for the implementation of part C prevention of significant deterioration (PSD) and part D new source review (NSR) permit programs; (5) include provisions for stationary source emission control measures, monitoring, and reporting; (6) include provisions for air quality modeling; and, (7) provide for public and local agency participation in planning and emission control rule development.

Section 110(a)(2)(D) of the CAA requires SIPs to contain measures to prevent sources in a State from significantly contributing to air quality problems in another State. To implement this provision, the EPA has required certain States to establish programs to address transport of certain ( printed page 18358) air pollutants, for example, the NO X SIP call, the Clean Air Interstate Rule (CAIR), and the Cross State Air Pollution Rule (CSAPR). Like many of the 110(a)(2) requirements, however, the section 110(a)(2)(D) SIP requirements are not linked with a particular area's ozone designation and classification. The EPA concludes that the SIP requirements linked with the area's ozone designation and classification are the relevant measures to evaluate when reviewing a redesignation request for the area. The section 110(a)(2)(D) requirements, where applicable, continue to apply to a State regardless of the designation of any one particular area within the State. Thus, we believe these requirements are not applicable requirements for purposes of redesignation. See 65 FR 37890 (June 15, 2000), 66 FR 53094 (October 19, 2001), 68 FR 25418, 25426 through 25427 (May 12, 2003).

In addition, the EPA believes that other section 110 elements that are neither connected with nonattainment plan submissions nor linked with an area's ozone attainment status are not applicable requirements for purposes of redesignation. The area will still be subject to these requirements after the area is redesignated to attainment of the 2015 ozone NAAQS. The section 110 and part D requirements which are linked with a particular area's designation and classification are the relevant measures to evaluate in reviewing a redesignation request. This approach is consistent with the EPA's existing policy on applicability (i.e., for redesignations) of conformity requirements, as well as with section 184 ozone transport requirements. See Reading, Pennsylvania proposed and final rulemakings, 61 FR 53174 through 53176 (October 10, 1996) and 62 FR 24826 (May 7, 1997); Cleveland-Akron-Loraine, Ohio final rulemaking, 61 FR 20458 (May 7, 1996); and Tampa, Florida final rulemaking, 60 FR 62748 (December 7, 1995). See also the discussion of this issue in the Cincinnati, Ohio ozone redesignation (65 FR 37890, June 19, 2000), and the Pittsburgh, Pennsylvania ozone redesignation (66 FR 53094, October 19, 2001).

We have reviewed Ohio's SIP and propose to find that it meets the general SIP requirements under section 110 of the CAA, to the extent those requirements are applicable for purposes of redesignation. In any case, on August 11, 2021 (86 FR 43962), the EPA approved elements of the SIP submitted by Ohio to meet the requirements of section 110 for the 2015 ozone standard.

b. Part D Requirements

Section 172(c) of the CAA sets forth the basic requirements of air quality plans for States with nonattainment areas that are required to submit them pursuant to section 172(b). Subpart 2 of part D, which includes section 182 of the CAA, establishes specific requirements for ozone nonattainment areas depending on the areas' nonattainment classifications.

The Cleveland area is classified as Serious under subpart 2 for the 2015 ozone NAAQS. As such, the area is subject to the subpart 1 requirements contained in section 172(c) and section 176. Similarly, the area is subject to the subpart 2 requirements contained in section 182(a) (Marginal nonattainment area requirements) and section 182(b) (Moderate nonattainment area requirements), and section 182(c) (Serious nonattainment area requirements). A thorough discussion of the requirements contained in section 172(c) and 182 can be found in the General Preamble for Implementation of Title I (April 16, 1992, 57 FR 13498). However, as discussed in section VI below, the EPA is proposing to adjust the deadline for Ohio to submit Serious SIP revisions for the Cleveland area to no later than December 5, 2026. Providing the EPA finalizes this SIP submittal deadline adjustment and the redesignation of the Cleveland area prior to December 5, 2026, Serious SIP requirements would not be applicable requirements for purposes of redesignation, because they will not have become due.

i. Subpart 1 Section 172 Requirements

As provided in subpart 2, for ozone nonattainment areas such as the Cleveland area, the specific requirements of section 182 apply in lieu of the attainment planning requirements that would otherwise apply under section 172(c), including the attainment demonstration and RACM under section 172(c)(1), RFP under section 172(c)(2), and contingency measures under section 172(c)(9). 42 U.S.C. 7511a(a).

Section 172(c)(3) requires submission and approval of a comprehensive, accurate and current inventory of actual emissions. This requirement is superseded by the inventory requirement in section 182(a)(1) discussed below.

Section 172(c)(4) requires the identification and quantification of allowable emissions for major new and modified stationary sources in an area, and section 172(c)(5) requires source permits for the construction and operation of new and modified major stationary sources anywhere in the nonattainment area. The EPA granted limited approval of approved Ohio's NSR program on September 8, 1993 (58 FR 47211) and granted final approval on January 10, 2003 (68 FR 1366). The EPA approved revisions to Ohio's NSR program on February 25, 2010 (75 FR 8496). Most recently, the EPA approved Ohio's certification that its SIP satisfies the nonattainment NSR requirements of the CAA for the 2015 ozone NAAQS on July 7, 2025 (90 FR 29742). Nonetheless, the EPA has determined that, since PSD requirements will apply after redesignation, areas being redesignated need not comply with the requirement that an NSR program be approved prior to redesignation, provided that the area demonstrates maintenance of the NAAQS without part D NSR. A more detailed rationale for this view is described in the October 14, 1994, memorandum from Mary Nichols, Assistant Administrator for Air and Radiation, entitled, “Part D New Source Review Requirements for Areas Requesting Redesignation to Attainment.” See rulemakings for Detroit, Michigan (60 FR 12467 through 12468, March 7, 1995); Cleveland-Akron-Lorain, Ohio (61 FR 20458, 20469-20470, May 7, 1996); Louisville, Kentucky (66 FR 53665, October 23, 2001); and Grand Rapids, Michigan (61 FR 31834 through 31837, June 21, 1996). Ohio's PSD program will become effective in the Cleveland area upon redesignation to attainment. The EPA conditionally approved Ohio's PSD program on October 10, 2001 (66 FR 51570), fully approved Ohio's PSD program on January 22, 2003 (68 FR 2909), and most recently approved revisions to Ohio's PSD program on February 25, 2010 (75 FR 8496).

Section 172(c)(6) requires the SIP to contain control measures necessary to provide for attainment of the NAAQS. Because attainment has been reached, no additional measures are needed to provide for attainment.

Section 172(c)(7) requires the SIP to meet the applicable provisions of section 110(a)(2). As noted above, we believe the Ohio SIP meets the requirements of section 110(a)(2) for purposes of redesignation.

ii. Section 176 Conformity Requirements

Section 176(c) of the CAA requires that federally supported or funded projects conform to the applicable SIP. The requirement to determine conformity applies to transportation plans, programs and projects that are developed, funded or approved under ( printed page 18359) title 23 of the United States Code (U.S.C.) and the Federal Transit Act (transportation conformity) as well as to all other federally supported or funded projects (general conformity). State transportation conformity SIP revisions must be consistent with Federal conformity regulations relating to consultation, enforcement and enforceability that the EPA promulgated pursuant to its authority under the CAA.

The EPA interprets the conformity SIP requirements [3 ] as not applying for purposes of evaluating a redesignation request under section 107(d) because State conformity rules are still required after redesignation and Federal conformity rules apply where State conformity rules have not been approved. See Wall v. EPA, 265 F.3d 426 (6th Cir. 2001) (upholding this interpretation); see also 60 FR 62748 (December 7, 1995) (redesignation of Tampa, Florida). Nonetheless, Ohio has an approved conformity SIP for the Cleveland area. See 80 FR 11133 (March 2, 2015).

iii. Subpart 2 Section 182(a), Section 182(b), Section 182(c), and Section 182(f) Requirements

Section 182(a)(1) requires States to submit a comprehensive, accurate, and current inventory of actual emissions from sources of NO X and VOC emitted within the boundaries of the ozone nonattainment area within two years of designation. The EPA approved Ohio's base year emissions inventory for the Cleveland area on March 3, 2021 (86 FR 12270) and July 7, 2025 (90 FR 29742).

Under section 182(a)(2)(A), States with ozone nonattainment areas that were designated prior to the enactment of the 1990 CAA amendments were required to submit, within six months of classification, all rules and corrections to existing VOC reasonably available control technology (RACT) rules that were required under section 172(b)(3) prior to the 1990 CAA amendments. The Cleveland area is not subject to the section 182(a)(2) RACT “fix up” requirement for the 2015 ozone NAAQS because it was designated as nonattainment for this standard after the enactment of the 1990 CAA amendments and, in any case, Ohio complied with this requirement for the Cleveland area under the prior 1-hour ozone NAAQS. See 59 FR 23796 (May 9, 1994) and 60 FR 15235 (March 23, 1995).

Section 182(a)(2)(B) requires each State with a Marginal ozone nonattainment area that implemented or was required to implement a vehicle I/M program prior to the 1990 CAA amendments to submit a SIP revision for an I/M program no less stringent than that required prior to the 1990 CAA amendments or already in the SIP at the time of the CAA amendments, whichever is more stringent. For the purposes of the 2015 ozone NAAQS and the consideration of Ohio's redesignation request for this standard, the Cleveland area is not subject to the section 182(a)(2)(B) requirement because the Cleveland area was designated as nonattainment for the 2015 ozone NAAQS after the enactment of the 1990 CAA amendments.

Regarding the source permitting and offset requirements of sections 182(a)(2)(C), 182(a)(4), and 182(b)(5), Ohio currently has a fully approved part D NSR program in place. The EPA granted limited approval of Ohio's NSR program on September 8, 1993 (58 FR 47211), and received final approval on January 10, 2003 (68 FR 1366). The EPA approved revisions to Ohio's NSR program on February 25, 2010 (75 FR 8496). Most recently, the EPA approved Ohio's certification that its SIP satisfies the nonattainment NSR requirements of the CAA for the 2015 ozone NAAQS on July 7, 2025 (90 FR 29742). In addition, the EPA conditionally approved Ohio's PSD program on October 10, 2001 (66 FR 51570), fully approved Ohio's PSD program on January 22, 2003 (68 FR 2909), and most recently approved revisions to Ohio's PSD program on February 25, 2010 (75 FR 8496). The State's PSD program will become effective in the Cleveland area upon redesignation to attainment.

Section 182(a)(3) requires States to submit periodic emission inventories and a revision to the SIP to require the owners or operators of stationary sources to annually submit emission statements documenting actual VOC and NO X emissions. As discussed below in section IV.D.4. of this proposed rule, Ohio will continue to update its emissions inventory at least once every three years consistent with the requirements of 40 CFR part 51, subpart A, and in 40 CFR 51.122. The EPA approved Ohio's emission statement SIP for the Cleveland area for the 2015 ozone NAAQS on July 11, 2017 (82 FR 31913).

Section 182(b)(1) requires the submission of an attainment demonstration and RFP plan. Ohio submitted an attainment demonstration and RFP plan for the Cleveland area on December 21, 2022. The EPA approved Ohio's RFP plan on July 7, 2025 (90 FR 29742). However, because attainment has been reached, section 182(b)(1) requirements are no longer considered to be applicable if the area continues to attain the standard. If the EPA finalizes approval of the redesignation of the area, the EPA will take no further action on the attainment demonstration submitted by Ohio.

Section 182(b)(2) requires States with Moderate nonattainment areas to implement VOC RACT with respect to each of the following: (1) all sources covered by a Control Technology Guideline (CTG) document issued between November 15, 1990, and the date of attainment; (2) all sources covered by a CTG issued prior to November 15, 1990; and (3) all other major non-CTG stationary sources. Ohio submitted a VOC RACT SIP to address the requirements applicable to Moderate nonattainment areas on March 30, 2022, and supplemented the submittal on February 1, 2023, and August 28, 2023. On January 20, 2026 (91 FR 2308) the EPA approved Ohio's submittal as satisfying the requirements of sections 182(b)(2)(A) and (B), that VOC RACT be implemented with respect to sources covered by a CTG and partially satisfying the requirement of section 182(b)(2)(C) that VOC RACT be implemented at all other major sources. Ohio subsequently submitted non-CTG VOC RACT determinations for sources at or above the Moderate major source threshold in the area on March 11, 2024, January 15, 2025, January 22, 2025, October 8, 2025, November 20, 2025, and November 25, 2025. The EPA is taking action on these VOC RACT determinations in separate rulemakings. The EPA will not finalize this redesignation unless the EPA has fully approved Ohio's Moderate VOC RACT SIP.

Section 182(b)(3) requires States to adopt Stage II gasoline vapor recovery regulations. On May 16, 2012 (77 FR 28772), the EPA determined that the use of onboard vapor recovery technology for capturing gasoline vapor when gasoline-powered vehicles are refueled is in widespread use throughout the highway motor vehicle fleet and waived the requirement that current and former ozone nonattainment areas implement Stage II vapor recovery systems on gasoline pumps.

Section 182(b)(4) requires a basic vehicle I/M program in each State with a moderate ozone nonattainment area. The EPA approved Ohio's basic I/M program of April 4, 1995 (60 FR 16986) and on January 6, 1997 (62 FR 646). The ( printed page 18360) EPA approved Ohio's I/M program certification for the Cleveland area for the Moderate classification under the 2015 ozone NAAQS on July 7, 2025 (90 FR 29742).

Section 182(c) contains the requirements for areas classified as Serious. As discussed in section VI, in this action the EPA is proposing to adjust the deadline for Ohio to submit Serious SIP revisions for the Cleveland area to no later than December 5, 2026. Provided the EPA finalizes this SIP submittal deadline adjustment and the redesignation of the Cleveland area prior to December 5, 2026, Serious SIP requirements would not be considered applicable requirements for purposes of redesignation because they will not have become due and thus are not a prerequisite to redesignation. Nonetheless, Ohio has already submitted many of the Serious SIP requirements, and the EPA is proposing to approve those submittals as follows.

Section 182(c)(1) of the CAA requires States with nonattainment areas classified Serious or higher to adopt and implement a program to improve air monitoring for ambient concentrations of ozone, NO X and VOC. For the reasons discussed in section IX, EPA is proposing to approve the Ohio's EMP certification for the 2015 ozone NAAQS.

CAA section 182(c)(3) requires States with ozone nonattainment areas classified as Serious or higher to adopt and implement an Enhanced I/M program. For the reasons discussed in section VII, below, the EPA is proposing to approve the Ohio I/M certification as meeting the section 182(c)(3) Serious Enhanced I/M requirements for the Cleveland area under the 2015 ozone NAAQS.

CAA section 182(c)(4) requires States with ozone nonattainment areas classified as Serious or higher to submit a SIP revision describing implementation of a CFVP, as described in CAA title II part C (40 CFR 88). For the reasons discussed in section VIII, the EPA is proposing to approve Ohio's certification that its current CFVP meets the Serious CFVP requirements for the Ohio area for the 2015 ozone NAAQS.

Section 182(c) of the CAA also requires States with Serious nonattainment areas to implement the VOC RACT requirements of Section 182(b)(2) with the addition that a “major source” is one that emits, or has the potential to emit, at least 50 tons per year of volatile organic compounds. Ohio has submitted part of the Serious VOC RACT requirements for the Cleveland nonattainment area. The EPA is proposing to extend the deadlines for those submittals, however, as described in section VI.

The remaining section 182(c) requirements for areas classified as Serious include: an attainment demonstration, RFP, RFP contingency measures, and a transportation control demonstration. These elements are not needed to redesignate the Ohio portion because the area has attained the 2015 ozone NAAQS. This rationale is outlined in 40 CFR 51.1318, the General Preamble, and the Calcagni memorandum at 6 (“The requirements for reasonable further progress and other measures needed for attainment will not apply for redesignations because they only have meaning for areas not attaining the standard.”). The EPA believes it is reasonable to interpret these provisions as not requiring areas that are meeting the ozone standard to make the SIP submissions to the EPA described in the provisions as long as the areas continue to meet the standard. (If such an area were to monitor a violation of the standard prior to being redesignated to attainment, however, the area would have to address the pertinent requirements and submit the SIP revisions described in those provisions to the EPA.)

Section 182(f) of the CAA establishes NO X requirements for ozone nonattainment areas. Section 182(f)(1) generally requires major sources of NO X to be covered by the same levels of emission controls as required for major sources of VOC. Since section 182(b)(2)(C) of the CAA requires areas classified as Moderate (or above) to implement RACT for major VOC sources, these ozone nonattainment areas are also required to implement NO X RACT for major sources of NO X. Ohio submitted a NO X RACT SIP at the Moderate major source threshold on March 30, 2022, and supplemented the submittal on February 1, 2023, and August 28, 2023. On January 20, 2026 (91 FR 2308), the EPA approved Ohio's SIP submissions as partially meeting the NO X RACT requirements of sections 182(b)(2) and 182(f) of the CAA at the Moderate major source threshold. For the major sources not subject to category-specific NO X RACT rules, Ohio subsequently submitted source specific NO X RACT determinations on December 5, 2023, March 28, 2024, July 28, 2025, August 25, 2025, and November 20, 2025. The EPA is taking action on Ohio's source specific Moderate NO X RACT determinations in separate rules. As noted below, providing the EPA finalizes the SIP submittal deadline adjustment and the redesignation of the Cleveland area prior to December 5, 2026, NO X RACT at the Serious major source threshold would not be an applicable requirement for purposes of redesignation because it will not have become due.

Thus, as discussed above, the EPA finds that the Cleveland, Ohio area satisfies all applicable requirements for purposes of redesignation under section 110 and part D of the CAA.

1. The Cleveland area has a fully approved SIP for purposes of redesignation under section 110(k) of the CAA.

At various times, Ohio has adopted and submitted, and the EPA has approved, provisions addressing the various SIP elements applicable for the ozone NAAQS. In separate actions, the EPA is proposing to approve Ohio's VOC and NO X RACT submissions as meeting the requirements for Moderate nonattainment areas. Providing the EPA finalizes approval of these VOC and NO X RACT submissions and finalizes the SIP submittal deadline adjustment and the redesignation of the Cleveland area prior to December 5, 2026, the EPA will have fully approved the Ohio SIP for the Cleveland area under section 110(k) for all requirements applicable for purposes of redesignation under the 2015 ozone NAAQS. The EPA may rely on prior SIP approvals in approving a redesignation request (see the Calcagni memorandum at page 3; Southwestern Pennsylvania Growth Alliance v. Browner, 144 F.3d 984, 989-990 (6th Cir. 1998); Wall v. EPA, 265 F.3d 426). Additional measures may also be approved in conjunction with a redesignation action (see 68 FR 25426 (May 12, 2003) and citations therein).

C. Are the air quality improvements in the Cleveland area due to permanent and enforceable emission reductions?

To redesignate an area from nonattainment to attainment, section 107(d)(3)(E)(iii) of the CAA requires the EPA to determine that the air quality improvement in the area is due to permanent and enforceable reductions in emissions resulting from the implementation of the SIP and applicable Federal air pollution control regulations and other permanent and enforceable emission reductions. The EPA proposes to determine that Ohio has demonstrated that that the observed ozone air quality improvement in the Cleveland area is due to permanent and enforceable reductions in VOC and NO X emissions resulting from State measures adopted into the SIP and Federal measures.

In making this demonstration, the State has calculated the change in emissions between 2017 and 2025. The reduction in emissions and the ( printed page 18361) corresponding improvement in air quality over this time period can be attributed to several regulatory control measures that the Cleveland area and upwind areas have implemented in recent years. In addition, Ohio provided an analysis to demonstrate the improvement in air quality was not due to unusually favorable meteorology. Based on the information summarized below, the EPA proposes to find that Ohio has adequately demonstrated that the improvement in air quality is due to permanent and enforceable emissions reductions.

1. Permanent and enforceable emission controls implemented.

a. Regional NO X Controls

CAIR/CSAPR. Under the “good neighbor provision” of CAA section 110(a)(2)(D)(i)(I), States are required to address interstate transport of air pollution. Specifically, the good neighbor provision provides that each State's SIP must contain provisions prohibiting emissions from within that State which will contribute significantly to nonattainment of the NAAQS, or interfere with maintenance of the NAAQS, in any other State.

On May 12, 2005 (70 FR 25152), the EPA published CAIR, which required eastern States, including Ohio, to prohibit emissions consistent with annual and ozone season NO X budgets and annual sulfur dioxide (SO 2) budgets. CAIR addressed the good neighbor provision for the 1997 ozone NAAQS and 1997 fine particulate matter (PM 2.5) NAAQS and was designed to mitigate the impact of transported NO X emissions, a precursor of both ozone and PM 2.5, as well as transported SO 2 emissions, another precursor of PM 2.5. The United States Court of Appeals for the District of Columbia Circuit (D.C. Circuit) remanded CAIR to the EPA for replacement in 2008. North Carolina v. EPA, 531 F.3d 896, modified, 550 F.3d 1176 (2008). While the EPA worked on developing a replacement rule, implementation of the CAIR program continued as planned with the NO X annual and ozone season programs beginning in 2009 and the SO 2 annual program beginning in 2010.

On August 8, 2011 (76 FR 48208), acting on the D.C. Circuit's remand, the EPA published CSAPR to replace CAIR and to address the good neighbor provision for the 1997 ozone NAAQS, the 1997 PM 2.5 NAAQS, and the 2006 PM 2.5 NAAQS. Through Federal Implementation Plans, CSAPR required electric generating units (EGUs) in eastern States, including Ohio, to meet annual and ozone season NO X budgets and annual SO 2 budgets implemented through new trading programs. After delays caused by litigation, the EPA started implementing the CSAPR trading programs in 2015, simultaneously discontinuing administration of the CAIR trading programs. On October 26, 2016 (81 FR 74504), the EPA published the CSAPR Update, which established, starting in 2017, a new ozone season NO X trading program for EGUs in eastern States, including Ohio, to address the good neighbor provision for the 2008 ozone NAAQS. The CSAPR Update was estimated to result in a 20% reduction in ozone season NO X emissions from EGUs in the eastern United States, a reduction of 80,000 tons in 2017 compared to 2015 levels. On April 30, 2021 (86 FR 23054), the EPA published the Revised CSAPR Update, which fully resolved the obligations of eastern States, including Ohio, under the good neighbor provision for the 2008 ozone NAAQS. The Revised CSAPR Update is estimated to reduce ozone season NO X emissions from EGUs by 17,000 tons beginning in 2021, compared to emissions without the rule. The reduction in NO X emissions from the implementation of CAIR and then CSAPR occurred by the attainment years.

b. Federal Emission Control Measures

Reductions in VOC and NO X emissions have occurred statewide and in upwind areas as a result of Federal emission control measures, with additional emission reductions expected to occur in the future. Further details on the various Federal emission control measures are described in the redesignation request submittal included in the docket of this action. Some of the listed Federal emission control measures include the following:

Tier 2 Emission Standards for Vehicles and Gasoline Sulfur Standards. On February 10, 2000 (65 FR 6698), the EPA promulgated Tier 2 motor vehicle emission standards and gasoline sulfur control requirements. These emission control requirements result in lower VOC and NO X emissions from new cars and light duty trucks, including sport utility vehicles. With respect to fuels, this rule required refiners and importers of gasoline to meet lower standards for sulfur, which were phased in between 2004 and 2006. By 2006, refiners and importers were required to meet a 30 ppm average sulfur level, with a maximum cap of 80 ppm. This reduction in fuel sulfur content ensures the effectiveness of low emission-control technologies. The Tier 2 tailpipe standards established in this rule were phased in for new vehicles between 2004 and 2009. At the time of promulgation of Tier 2 standards, the EPA estimated that this rule would cut NO X and VOC emissions from light-duty vehicles and light-duty trucks by approximately 76% and 28%, respectively. NO X and VOC reductions from medium-duty passenger vehicles included as part of the Tier 2 vehicle program were estimated to be approximately 37,000 and 9,500 tons per year, respectively, when fully implemented. As projected by these estimates and demonstrated in the onroad emission modeling for the Cleveland area, a portion of these emission reductions occurred during the period 2017 through 2025, i.e., after the area was designated nonattainment for the 2015 ozone NAAQS. As discussed below, the Tier 2 vehicle and gasoline sulfur standards were replaced by the Tier 3 emission standards for vehicles and gasoline sulfur standards beginning on January 1, 2017.

Tier 3 Emission Standards for Vehicles and Gasoline Sulfur Standards. On April 28, 2014 (79 FR 23414), the EPA promulgated Tier 3 motor vehicle emission and fuel standards to reduce both tailpipe and evaporative emissions and to further reduce the sulfur content in fuels. The rule was phased in between 2017 and 2025. Tier 3 sets new tailpipe standards for non-methane organic gases (NMOG) and NO X, presented as NMOG+NO X, and for particulate matter. The VOC and NO X tailpipe standards for light-duty vehicles represent approximately an 80% reduction in fleet average NMOG+NO X and a 70% reduction in per-vehicle particulate matter (PM) standards, relative to the fleet average at the time of phase-in. Heavy-duty tailpipe standards represent about a 60% reduction in both fleet average NMOG+NO X and per-vehicle PM standards. The evaporative emissions requirements in the rule will result in approximately a 50% reduction from previous standards and apply to all light-duty and onroad gasoline-powered heavy-duty vehicles. Finally, the rule lowered the sulfur content of gasoline to an annual average of 10 ppm starting in January 2017. As projected by these estimates and demonstrated in the onroad emission modeling for the Cleveland area, some of these emission reductions occurred by the attainment years and additional emission reductions will occur throughout the maintenance period, as older vehicles are replaced with newer, compliant model years.

Heavy-Duty Diesel Engine Rules. On January 18, 2001 (66 FR 5002), the EPA ( printed page 18362) issued a rule for onroad heavy-duty diesel engines that includes standards limiting the sulfur content of diesel fuel. Emissions standards for NO X, VOC and PM were phased in between model years 2007 and 2010. In addition, the rule reduced the highway diesel fuel sulfur content to 15 parts per million by 2007, leading to additional reductions in combustion NO X and VOC emissions. The EPA has estimated future year emission reductions due to implementation of this rule. The EPA estimated that by 2015 NO X and VOC emissions would decrease nationally by 1,260,000 tons and 54,000 tons, respectively, and that by 2030 NO X and VOC emissions will decrease nationally by 2,570,000 tons and 115,000 tons, respectively. As projected by these estimates and demonstrated in the onroad emission modeling for the Cleveland area, some of these emission reductions occurred by the attainment years and additional emission reductions will occur throughout the maintenance period, as older vehicles are replaced with newer, compliant model years.

Nonroad Diesel Rule. On June 29, 2004 (69 FR 38958), the EPA issued a rule adopting emissions standards for nonroad diesel engines and sulfur reductions in nonroad diesel fuel. This rule applies to diesel engines used primarily in construction, agricultural, and industrial applications. Emission standards were phased in for the 2008 through 2015 model years based on engine size. The sulfur limits for nonroad diesel fuels were phased in from 2007 through 2012. The EPA estimates that when fully implemented, compliance with this rule will cut NO X emissions from these nonroad diesel engines by approximately 90%. As projected by these estimates and demonstrated in the nonroad emission modeling for the Cleveland area, some of these emission reductions occurred by the attainment years and additional emission reductions will occur throughout the maintenance period.

Nonroad Spark-Ignition Engines and Recreational Engine Standards. On November 8, 2002 (67 FR 68242), the EPA adopted emission standards for large spark-ignition engines such as those used in forklifts and airport ground-service equipment; recreational vehicles such as off-highway motorcycles, all-terrain vehicles, and snowmobiles; and recreational marine diesel engines. These emission standards were phased in from model years 2004 through 2012. When fully implemented, the EPA estimates an overall 72% reduction in national VOC emissions from these engines and an 80% reduction in national NO X emissions. As projected by these estimates and demonstrated in the nonroad emission modeling for the Cleveland area, some of these emission reductions occurred by the attainment years and additional emission reductions will occur throughout the maintenance period as older engines are replaced with newer, compliant model years.

Category 3 Marine Diesel Engine Standards. On April 30, 2010 (75 FR 22896), the EPA issued emission standards for marine compression-ignition engines at or above 30 liters per cylinder. Tier 2 emission standards apply beginning in 2011 and are expected to result in a 15 to 25% reduction in NO X emissions from these engines. Final Tier 3 emission standards apply beginning in 2016 and are expected to result in approximately an 80% reduction in NO X from these engines. As projected by these estimates and demonstrated in the nonroad emission modeling for the Cleveland area, some of these emission reductions occurred by the attainment years and additional emission reductions will occur throughout the maintenance period as older engines are replaced with newer, complaint model years.

In its submittal, Ohio included additional permanent and enforceable Federal emission control measures that contributed to NO X and VOC emission reductions by the attainment years, and which will contribute to additional emission reductions throughout the maintenance period. Further information can be found in Chapter Five of Ohio's submittal.

c. Ohio Rules

Consumer Products Rules. On June 20, 2022, Ohio revised its consumer products rules to incorporate the Phase IV Ozone Transport Commission (OTC) model rule. Implementation was required by July 1, 2023.

Architectural and Industrial Maintenance (AIM) Coatings Rules. Effective December 16, 2022, Ohio revised its AIM rules to incorporate the OTC Phase II standards, with an implementation date of January 1, 2024.

VOC and NO X RACT. While VOC and NO X regulations have been in place in Ohio for many years, Ohio revised certain source categories to establish new or more stringent RACT controls. Revisions to Ohio's VOC and NO X RACT rules became effective March 27, 2022, and March 25, 2022, respectively.

d. Cleveland Point Source NO X Reductions.

The Avon Lake Power Plant (Facility ID: 0247030013) ceased operations in April 2022. In its submittal, Ohio EPA estimated this shutdown would reduce annual point source NO X emissions by 1,069.10 tons.

1. Emission reductions.

Ohio is using a 2017 emissions inventory to represent nonattainment level emissions (nonattainment year inventory or nonattainment inventory), which is appropriate because it was a year the area monitored nonattainment due to an exceedance of the NAAQS, and it corresponds to the base year approved by the EPA on July 7, 2025 (90 FR 29742), for Ohio EPA's Moderate attainment demonstration request and RFP demonstration. Ohio is using a 2025 emissions inventory to represent attainment level emissions (attainment year inventory or attainment inventory), which is appropriate because it is one of the years in the 2023-2025 period used to demonstrate monitored attainment with the NAAQS.

For both 2017 and 2025, Ohio has provided inventories for point, nonpoint, onroad, and nonroad sources. The point source category includes facilities that report their emissions directly to Ohio EPA, as well as sources such as airports and rail yards. Nonpoint sources, sometimes called area sources, include emissions from sources that are more ubiquitous, such as consumer products or architectural coatings. Onroad sources are vehicles that are primarily used on public roadways, such as cars, trucks, and motorcycles. Nonroad sources include engine-based emissions that do not occur on roads, such as trains or boats.

For its onroad emissions inventory, Ohio submitted an analysis developed by Ohio's Department of Transportation (ODOT), the Akron Metropolitan Area Transportation Study (AMATS), and the Northeast Ohio Areawide Coordinating Agency (NOACA), in consultation with Ohio EPA and the EPA. This analysis used the EPA's Motor Vehicle Emission Simulator (MOVES) model to generate July weekday onroad emissions informing the inventories for both 2017 and 2025. However, Ohio EPA used 2026 modeled emissions as a conservative estimate for mobile emissions used in their demonstration to represent 2025 emissions. The MOVES5 model was the latest model version available at the time the inventory was developed. NOACA, AMATS, and ODOT's analysis relied on local travel inputs including demographic data, travel demand ( printed page 18363) forecasting, road types, Vehicle Miles of Travel (VMT), Vehicle Hours of Travel, vehicle population, and vehicle age, as well as meteorological data. In appendix C of its submittal, Ohio has included a detailed narrative of ODOT, AMATS, and NOACA's methods.

For its point, nonpoint, and nonroad emissions inventories, Ohio's primary data sources were the EPA's 2017gb emissions modeling platform based on the 2017 National Emissions Inventory (NEI)—Version 2 dataset, and the EPA's 2022v1 emissions modeling platform, based on the 2020 NEI. The 2017 NEI includes emissions data only for the year 2017, and the 2022v1 modeling platform includes emissions data for the years 2026, 2032, and 2038. The 2022v1 modeling platform and 2017 NEI have been quality-assured, and documentation regarding these datasets and their methods is available on the EPA's website. [4 ]

For the 2017 inventories, Ohio EPA used the 2017gb emissions modeling platform [5 ] as the basis of its point, nonpoint, and nonroad inventories and these emissions are presented in terms of monthly or annual emissions.

To derive point inventories for 2025, Ohio EPA relied on 2023 actual point emissions to represent 2025 since at the time of the request, actual point emissions for 2024 and 2025 were not available. Ohio EPA determined that 2023 actual point source emissions would be a conservative estimate for 2025 actual point source emissions. Ohio EPA performed a review and did not find any new sources in the area and also reviewed to ensure any shutdown sources were removed. The 2023 actual point source inventory is submitted to the EPA's Emissions Inventory System (EIS). In appendix B of its submittal, Ohio has included a detailed listing of the facilities used to create the point source inventory for 2025. To derive nonpoint and nonroad inventories for 2025, Ohio EPA based 2025 emissions on 2026 projected emissions from the 2022v1 emissions modeling platform.

Ohio EPA summed the annual totals of NO X and VOC emissions for each county and each source category in tons per ozone season day (TPOSD) using conversion factors derived from the EPA's 2017gb emissions modeling platform. The derived ozone season day emissions include weekend days. Ohio EPA determined that this is appropriate because ozone values measured on weekend days have a significant impact on the monitor design values in the Cleveland area. Monitoring data from 2017 through 2022 show the Cleveland nonattainment area had between 5 and 7 days with one or more monitors recording values over the 2015 ozone standard each year, with up to 3 of those days in a year falling on a weekend. In addition, for each year from 2017 to 2022, between 5 and 18 of the 1st through 4th high values that contributed to the design value for a monitor occurred on a weekend day. As such, Ohio EPA determined that it was appropriate to include weekend emissions in the calculation of ozone season day emissions.

Ohio EPA derived ozone season day emissions in TPOSD emissions by dividing July emissions by the number of days in July where only monthly data was available. Where only annual data were available, Ohio EPA applied a conversion factor to annual emissions. Conversion factors were derived as a ratio of the 2017 average July day emissions to 2017 annual emissions, and then dividing by 31 to represent the number of days in July. Ohio EPA selected July as representative of the standard ozone season month as it is typically the warmest month and had the highest monthly emissions as a result of an analysis showing that July had the most days with high ozone values in recent years.

Using the inventories described above for all categories of sources, Ohio's submittal documents changes in NO X and VOC emissions from 2017 to 2025 for the Cleveland area. Emissions data are shown in Table 2. Data are expressed in terms of tons per ozone season day.

| | NO X | | | VOC | | |
| --- | --- | --- | | | | |
| 2017 | 2025 | Net change
(2017-2025) | 2017 | 2025 | Net change
(2017-2025) | |
| Point | 14.38 | 8.82 | −5.56 | 7.91 | 6.10 | −1.81 |
| Nonpoint | 16.49 | 17.18 | 0.69 | 116.60 | 95.78 | −20.82 |
| Onroad | 51.91 | 12.16 | −30.75 | 31.69 | 17.72 | −13.97 |
| Nonroad | 25.29 | 15.46 | −9.83 | 33.81 | 22.34 | −11.47 |
| Total | 108.07 | 62.62 | −45.45 | 190.01 | 141.94 | −48.07 |
As shown in Table 2, Ohio's inventories demonstrate that NO X and VOC emissions in the Cleveland area declined by 45.45 tons per ozone season day and 48.07 tons per ozone season day, respectively, between 2017 and 2025.

1. Meteorology and temporary adverse economic conditions.

To further support Ohio EPA's demonstration that the improvement in air quality is due to permanent and enforceable emission reductions, and not unusually favorable meteorology or temporary adverse economic conditions, the demonstration includes two analyses performed by the Lake Michigan Air Directors Consortium (LADCO).

The first LADCO analysis compared trends in ozone to trends in ozone season temperatures, examining the relationship between these two factors. LADCO utilized two different metrics of ozone, the annual fourth-high daily maximum eight-hour average (MDA8) ozone value, and the number of days in a year with MDA8 ozone greater than 70 parts per billion (ppb) for the years 2005 to 2025. The ozone values were compared with two measures of “hotness” of an ozone season: (1) average May to September temperatures and (2) the number of days with a temperature exceeding 80 °F. ( printed page 18364)

LADCO conducted a meteorological analysis based on 22 years of data collected at the Cleveland-Hopkins International Airport, WBAN 14820 meteorological station, representative of the area conditions and used for New Source Review and Prevention of Significant Deterioration air quality permit modeling applications. LADCO analyzed ozone values for May, June, July, August, and September, for years 2005 to 2025. First, the annual fourth high MDA8 ozone concentration at the Eastlake Monitor (Site ID: 39-085-0003) was compared to the average May to September temperature at the airport. Second, LADCO examined the relationship between the number of days with temperatures over 80 °F and the number of days with MDA8 ozone above 70 ppb. The data with the ozone parameters was plotted against the temperature parameters and grouped into 7-year time periods. These analyses show that over the last 22 years, the amount of ozone production for a given level of “hotness” has decreased in each subsequent time period. In contrast, temperatures have increased, with the area showing an overall warming trend. Because the correlation between temperature and ozone formation is well established, these data suggest that reductions in precursors are responsible for the reductions in ozone concentrations in the area, and not unusually favorable summer temperatures.

To further support Ohio EPA's demonstration that the improvement in air quality is not due to unusually favorable meteorology, a second analysis was performed by LADCO. A classification and regression tree (CART) analysis was conducted with 2001 through 2023 data from Cleveland area ozone sites. The goal of the analysis was to determine the meteorological and air quality conditions associated with ozone episodes, and construct trends for the days identified as sharing similar meteorological conditions. Regression trees were developed for the Cleveland area ozone data to classify each summer day by its ozone concentration and associated meteorological conditions. By grouping days with similar meteorology, the influence of meteorological variability on the underlying trend in ozone concentrations is partially removed and the remaining trend is presumed to be due to trends in precursor emissions or other non-meteorological influences. The CART analysis showed the resulting trends in ozone concentrations declining over the period examined, supporting the conclusion that the improvement in air quality was not due to unusually favorable meteorology. In appendix D of its submittal, Ohio included a detailed report of LADCO's analysis.

To determine attainment was not due to adverse economic conditions, the EPA analyzed Ohio employment status data taken from the U.S. Census Bureau's American Community Survey from 2015 through 2023, noting an overall increasing trend in employment rates in the Cleveland area. [6 ] Additionally, the gross domestic product (GDP) of the Cleveland metropolitan statistical area from 2013-2023 shows an increasing trend. [7 ] Despite increases employment and GDP, ozone concentrations in the Cleveland area show a decreasing trend, leading to attainment of the 2015 ozone NAAQS and indicating attainment of the 2015 standard was not due to temporary adverse economic conditions.

As discussed above, Ohio identified numerous Federal rules that resulted in the reduction of VOC and NO X emissions from 2017 to 2025. In addition, Ohio's analyses of meteorological variables associated with ozone formation demonstrate that the improvement in air quality in the area between the year violations occurred and the year attainment was achieved is not due to unusually favorable meteorology. The EPA reviewed employment and GDP data for the Cleveland area to verify that emissions reductions were not due to temporary adverse economic conditions but rather were consistent with a longer-term trend of decreasing ozone concentrations. Therefore, the EPA proposes to find that Ohio has shown that the air quality improvements in the Cleveland area are due to permanent and enforceable emissions reductions.

D. Does Ohio have a fully approvable ozone maintenance plan for the Cleveland area?

To redesignate an area from nonattainment to attainment, section 107(d)(3)(E)(iv) of the CAA requires the EPA to determine that the area has a fully approved maintenance plan pursuant to section 175A of the CAA. Section 175A of the CAA sets forth the elements of a maintenance plan for areas seeking redesignation from nonattainment to attainment. Under section 175A, the maintenance plan must demonstrate continued attainment of the NAAQS for at least 10 years after the Administrator approves a redesignation to attainment. Eight years after the redesignation, the State must submit a revised maintenance plan which demonstrates that attainment of the NAAQS will continue for an additional 10 years beyond the initial 10-year maintenance period. To address the possibility of future NAAQS violations, the maintenance plan must contain contingency measures, as the EPA deems necessary, to assure prompt correction of the future NAAQS violation.

The Calcagni Memorandum provides further guidance on the content of a maintenance plan, explaining that a maintenance plan should address five elements: (1) an attainment emission inventory; (2) a maintenance demonstration; (3) a commitment for continued air quality monitoring; (4) a process for verification of continued attainment; and (5) a contingency plan. In conjunction with its request to redesignate the Cleveland area to attainment for the 2015 ozone NAAQS, Ohio submitted a SIP revision to provide for maintenance of the 2015 ozone NAAQS through 2038, more than 10 years after the expected effective date of the redesignation to attainment. As discussed below, the EPA proposes to find that Ohio's ozone maintenance plan includes the necessary components and to approve the maintenance plan as a revision of the Ohio SIP.

1. Attainment Inventory

In the CDD, the EPA proposed to determine that the Cleveland area has attained the 2015 ozone NAAQS based on monitoring data for the period of 2023-2025. See 91 FR 9771 (February 27, 2026). Ohio selected 2025 as the attainment emissions inventory year to establish attainment emission levels for VOC and NO X. The attainment emissions inventory identifies the levels of emissions in the Cleveland area that are sufficient to attain the 2015 ozone NAAQS. The derivation of the attainment year emissions is discussed above in section IV.C.2. of this proposed rule. The emissions for the 2025 attainment year, by source category, are summarized in Table 2 above.

2. Has the State demonstrated maintenance of the ozone standard in the Cleveland area?

Ohio has demonstrated maintenance of the 2015 ozone NAAQS through 2038 by projecting that current and future emissions of VOC and NO X for the ( printed page 18365) Cleveland area remain at or below attainment year emission levels. A maintenance demonstration need not be based on modeling. See Wall v. EPA, 265 F.3d 426 (6th Cir. 2001), Sierra Club v. EPA, 375 F. 3d 537 (7th Cir. 2004). See also 66 FR 53094, 53099 through 53100 (October 19, 2001), 68 FR 25413, 25430-25432 (May 12, 2003).

Ohio is using emissions inventories for the years 2032 and 2038 to demonstrate maintenance. The year 2038 was selected because it is more than 10 years after the expected effective date of the redesignation to attainment, and 2032 was selected to demonstrate that emissions are not expected to spike in the interim between the 2025 attainment year and the 2038 final maintenance year.

To develop emissions inventories for the years 2032 and 2038, Ohio used the same data sources discussed above in section IV.C.2. of this proposed rule.

For its onroad emissions inventory, Ohio again relied upon the ODOT, AMATS, and NOACA's analysis, which used the EPA's MOVES5 model to generate July weekday onroad emissions for 2032 and 2038. This interagency analysis relied on local travel inputs including demographic data, travel demand forecasting, road types, VMT, Vehicle Hours of Travel, vehicle population, and vehicle age, as well as meteorological data. In appendix C of its submittal, Ohio has included a detailed narrative of ODOT, AMATS, and NOACA's methods.

For its point, nonpoint, and nonroad emissions inventories, Ohio again used the EPA's 2022v1 emissions modeling platform for the 2025 attainment year, and the 2032 and 2038 projected inventories. Both the 2032 and 2038 emissions data for the area were derived from the EPA-projected 2032 and 2038 emissions from the 2022v1 modeling platform, version 2032hc and 2038hc respectively, without modification. For both the 2032 and 2038 inventories, to convert annual emissions totals into a value of tons per ozone season day, Ohio EPA calculated conversion factors using the same methodology described in section IV.C.2. of this proposed rule.

Emissions data for the 2017 nonattainment year, 2025 attainment year, 2032 interim year, and 2038 maintenance year are shown in Tables 3 and 4 below. Data are expressed in terms of tons per ozone season day.

| | 2017 | 2025 | 2032 | 2038 | Net change
(2025-2038) |
| --- | --- | --- | --- | --- | --- |
| Point | 14.38 | 8.82 | 10.51 | 9.91 | +1.09 |
| Nonpoint | 16.49 | 17.18 | 16.47 | 16.75 | −0.43 |
| Onroad | 51.91 | 21.16 | 11.44 | 6.71 | −14.45 |
| Nonroad | 25.29 | 15.46 | 14.29 | 14.62 | −0.84 |
| Total | 108.07 | 62.62 | 52.17 | 47.99 | −14.63 |

| | 2017 | 2025 | 2032 | 2038 | Net change
(2025-2038) |
| --- | --- | --- | --- | --- | --- |
| Point | 7.91 | 6.10 | 6.74 | 6.90 | +0.80 |
| Nonpoint | 116.60 | 95.78 | 92.21 | 91.15 | −4.63 |
| Onroad | 31.69 | 17.72 | 12.17 | 8.35 | −9.37 |
| Nonroad | 33.81 | 22.34 | 22.29 | 22.37 | +0.03 |
| Total | 190.01 | 141.94 | 133.41 | 128.77 | −13.17 |
As shown in Tables 3 and 4, NO X and VOC emissions in the Cleveland area are projected to decrease by 14.63 tons per ozone season day and 13.17 tons per ozone season day, respectively, between the 2025 attainment year and 2038 maintenance year. Ohio's maintenance demonstration for the Cleveland area shows maintenance of the 2015 ozone NAAQS by providing emissions information to support the demonstration that future emissions of NO X and VOC will remain at or below 2025 emission levels when considering both future source growth and implementation of future controls.

3. Continued Air Quality Monitoring

Ohio has committed to continue to operate its ozone monitors in the Cleveland area for the duration of the maintenance period. Ohio remains obligated to meet monitoring requirements, to continue to quality assure monitoring data in accordance with 40 CFR part 58, and to enter all data into the AQS in accordance with Federal guidelines.

4. Verification of Continued Attainment

Ohio has confirmed that it has the legal authority to enforce and implement the requirements of its SIP. Ohio has further committed that it has the authority to implement the requested SIP revision, which would include the maintenance plan for the Cleveland area. This includes the authority to adopt, implement, and enforce any subsequent emission control measures determined to be necessary to correct future ozone attainment problems.

Verification of continued attainment is accomplished through operation of the ambient ozone monitoring network and the periodic update of the area's emissions inventory. Ohio will continue to operate the ozone monitors located in the Cleveland area. There are no plans to discontinue operation, relocate, or otherwise change the existing ozone monitoring network other than through ( printed page 18366) revisions in the network approved by the EPA.

In addition, to track future levels of emissions, Ohio will continue to develop and submit to the EPA updated emission inventories for all source categories at least once every three years, consistent with the requirements of 40 CFR part 51, subpart A, and in 40 CFR 51.122. The Consolidated Emissions Reporting Rule (CERR) was promulgated by the EPA on June 10, 2002 (67 FR 39602). The CERR was replaced by the Annual Emissions Reporting Requirements on December 17, 2008 (73 FR 76539). The most recent triennial inventory for Ohio was compiled for 2020, and 2023 is in progress. Point source facilities covered by Ohio's emission statement rule, Ohio Administrative Code Chapter 3745-24, will continue to submit VOC and NO X emissions on an annual basis.

5. What is the contingency plan for the Cleveland area?

Section 175A of the CAA requires that the State adopt a maintenance plan as a SIP revision that includes such contingency measures as the EPA deems necessary to assure that the State will promptly correct a violation of the NAAQS that occurs after redesignation of the area to attainment of the NAAQS. The maintenance plan must identify: the contingency measures to be considered and, if needed for maintenance, adopted and implemented; a schedule and procedure for adoption and implementation; and a time limit for action by the State. The State should also identify specific indicators to be used to determine when the contingency measures need to be considered, adopted, and implemented. The maintenance plan must include a commitment that the State will implement all measures with respect to the control of the pollutant that were contained in the SIP before redesignation of the area to attainment in accordance with section 175A(d) of the CAA.

As required by section 175A of the CAA, Ohio has adopted a contingency plan for the Cleveland area to address possible future ozone air quality problems. The contingency plan adopted by Cleveland has two levels of response, a warning level response and an action level response.

In Ohio's plan, a warning level response will be triggered when an annual fourth-highest monitored value of 0.074 ppm or higher is monitored within the maintenance area. A warning level response will require Ohio to conduct a study. The study would assess whether the ozone value indicates a trend toward a higher ozone value and whether emissions appear to be increasing. The study will evaluate whether the trend, if any, is likely to continue and, if so, the control measures necessary to reverse the trend, taking into account ease and timing of implementation, as well as economic and social considerations. Any implementation of necessary controls in response to a warning level response trigger will occur within 12 months of the conclusion of the most recent ozone season. Additionally, the warning level study will assess whether ozone values were recorded as a result of a wildfire or other event that would qualify for data exclusion under the EPA's exceptional events rule, and the appropriate action level response control measures to follow.

In Ohio's plan, an action level response would be triggered when the fourth-highest monitored value, averaged over two years of 0.071 ppm or higher is monitored within the maintenance area. The action level response will also be triggered by a violation of the NAAQS (a three-year average fourth high value exceeding 0.071 ppm). When an action level response is triggered and not found to be due to an exceptional event, malfunction, or noncompliance with a permit condition or rule requirement, Ohio in conjunction with the metropolitan organization or regional council of governments, will determine what additional control measures are needed to assure future attainment of the 2015 ozone NAAQS. Control measures selected will be adopted and implemented within 18 months from the close of the ozone season that prompted the action level. As part of this response strategy, Ohio may also consider whether new regulations not currently included as part of the maintenance provisions will be implemented in a timely manner and would thus constitute an adequate contingency measure response.

Ohio's plan has a prescriptive process for determining if an action level response was due to an exceptional event. The purpose of this process is to differentiate between exceedances that are not within the State's control (i.e., exceedances that occur despite the implementation of reasonable measures), and exceedances that are within the State's control and should be included in the trigger calculation. It is important to note that, should Ohio EPA exclude an exceedance from the contingency trigger calculation using this process, it would not constitute the EPA's concurrence under 40 CFR 50.14 that the exceedance was caused by an exceptional event. The exceedance will therefore continue to be included in design value calculations for the area unless Ohio EPA, following opportunity for public comment, submits a request for the EPA to concur on the exceedance as an exceptional event pursuant to 40 CFR 50.14, and the EPA reviews the submittal and formally concurs.

Under this process, following a contingency triggering event, Ohio EPA will review impacted monitoring data to determine if exceptional events occurred, transmit an initial notification to the EPA, prepare a report of any exceptional events, and provide that report to the EPA. [8 ] Within 5 months of the conclusion of the ozone season, Ohio will complete and submit to the EPA a list of exceedances that occurred during that previous ozone season, and Ohio will designate proposed days as potential exceptional event exceedances, flag the relevant data, and provide initial event description in AQS.

Following submittal of the ozone season reports, the EPA will review the submitted information and notify Ohio if the submitted information is insufficient to support exclusion from the contingency plan trigger calculations, in which case Ohio will begin implementation of potential contingency measures described below. Ohio has the opportunity to provide additional information to the EPA. If the EPA finds this additional information is sufficient to support the conclusion that the exceedance meets the criteria for exclusion from the contingency plan trigger calculation, the EPA will notify Ohio that the trigger calculation will be adjusted. If the resulting value is less than 0.071 ppm, implementation of the contingency plan can be halted unless triggered in a subsequent ozone season.

The EPA proposes to find the contingency provisions of the Cleveland area clearly identify specific contingency measures, contain triggering mechanisms to determine when contingency measures are needed, contain description of the process recommending and implementing contingency measures, and contain specific and appropriate timelines for action. The EPA also proposes to find ( printed page 18367) that the contingency trigger screening process, including the associated the EPA review, is reasonably designed to distinguish between exceedances that are the type that have been deemed exceptional events in the past and exceedance for which new tightened control measures might be effective. The EPA's assessment indicates that the screening process is an appropriate element of the contingency plan for the Cleveland area due to the possibility of exceedances related to wildfire smoke events impacting this area. Thus, the EPA proposes to conclude that the contingency plan in the Cleveland redesignation request is adequate to ensure prompt correction of any violation of the 2015 ozone NAAQS that occurs after redesignation, as required by section 175A(d) of the CAA.

Ohio included the following list of potential contingency measures in its maintenance plan. Ohio may choose measures beyond those on this:

1. Tighten VOC or NO X RACT rules for existing sources covered by Control Technique Guidelines issued after the 1990 CAA;

2. Application of VOC RACT on existing, smaller sources;

3. Alternative fuel and diesel retrofit programs for fleet vehicle operations;

4. VOC or NO X control on new minor sources emitting less than 100 tons per year;

5. Increased ratio of emission offsets for new sources;

6. VOC or NO X emission offsets for new and modified major sources;

7. Adoption of additional NO X RACT for existing combustion sources;

8. Trip reduction programs;

9. Traffic flow and transit improvements; and

10. New or innovative transportation measures that local governments deem appropriate that are not yet widely implemented.

To qualify as a contingency measure, emissions reductions from that measure must not be factored into the emissions projections used in the maintenance plan. Ohio EPA also included a list of potential VOC and NO X sources subject to further future control under VOC RACT and NO X RACT. Control measures are subject to necessary administrative and legal processes such as publication of notices, public comment period, and other measures as required by Ohio law for rulemaking.

The EPA has concluded that Ohio's maintenance plan adequately addresses the five basic components of a maintenance plan: attainment inventory, maintenance demonstration, monitoring network, verification of continued attainment, and a contingency plan. In addition, as required by section 175A(b) of the CAA, Ohio has committed to submit to the EPA an updated ozone maintenance plan eight years after redesignation of the Cleveland area to cover an additional ten years beyond the initial 10-year maintenance period. Thus, the EPA finds that the maintenance plan SIP revision submitted by Ohio for the Cleveland area meets the requirements of section 175A of the CAA, and the EPA proposes to approve it as a revision to the Ohio SIP.

V. Has the State adopted approvable motor vehicle emission budgets?

A. Motor Vehicle Emission Budgets

Under section 176(c) of the CAA, new transportation plans, programs, or projects that receive Federal funding or support, such as the construction of new highways, must “conform” to (i.e., be consistent with) the SIP. Conformity to the SIP means that transportation activities will not cause or contribute to any new air quality violations, increase the frequency or severity of any existing air quality problems, or delay timely attainment or any required interim emissions reductions or any other milestones. Regulations at 40 CFR part 93 set forth the EPA policy, criteria, and procedures for demonstrating and ensuring conformity of transportation activities to a SIP. Transportation conformity is a requirement for nonattainment and maintenance areas.

Under the CAA, States are required to submit, at various times, control strategy SIPs for nonattainment areas and maintenance plans for areas seeking redesignations to attainment of the ozone standard and maintenance areas. See the SIP requirements for the 2015 ozone standard in the EPA's December 6, 2018 (83 FR 62998), implementation rule. These control strategy SIPs (including RFP and attainment plans) and maintenance plans must include motor vehicle emissions budgets for criteria pollutants, including ozone, and their precursor pollutants (VOC and NO X) to address pollution from onroad transportation sources. The budgets are the portion of the total allowable emissions that are allocated to highway and transit vehicle use that, together with emissions from other sources in the area, will provide for attainment or maintenance. See 40 CFR 93.101.

Under 40 CFR part 93, a budget for an area seeking a redesignation to attainment must be established, at a minimum, for the last year of the maintenance plan. A State may adopt budgets for other years as well. The budget serves as a ceiling on emissions from an area's planned transportation system. The budget concept is further explained in the preamble to the November 24, 1993 (58 FR 62188), Transportation Conformity Rule. The preamble also describes how to establish the budget(s) in the SIP and how to revise the budget(s), if needed, after initially establishing a budget in the SIP.

As discussed earlier, Ohio's maintenance plan includes NO X and VOC budgets for the Cleveland area for 2032, which is an interim year, as well as 2038, which is the last year of the maintenance period. The EPA has reviewed Ohio's NO X and VOC budgets for the area and, in this action, is proposing to approve them. [9 ] We are also starting the adequacy review process for these budgets to determine if they meet the adequacy criteria in the transportation conformity regulations (40 CFR 93.118(e)(4)). Ohio's December 8, 2025, maintenance plan submission, including the budgets for this area, is available for public comment via this proposed rulemaking. The submission was endorsed by the Governor's designee and Ohio provided opportunity for a public hearing. The budgets were developed as part of an interagency consultation process which includes Federal, State, and local agencies. The budgets were clearly identified and precisely quantified. These budgets, when considered together with all other emissions sources, are consistent with maintenance of the 2015 ozone NAAQS.

( printed page 18368)
| | 2032 Interim year | | | 2038 Maintenance year | | |
| --- | --- | --- | | | | |
| Projected onroad
emissions | Safety margin allocation | Total budget | Projected onroad
emissions | Safety margin allocation | Total budget | |
| NO X | 11.44 | 1.72 | 13.16 | 6.71 | 1.01 | 7.72 |
| VOCs | 12.60 | 1.89 | 14.49 | 8.63 | 1.29 | 9.92 |
As shown in Table 5, the 2032 and 2038 budgets exceed the estimated 2032 and 2038 onroad sector emissions. To accommodate future variations in VMT in the area, Ohio EPA allocated to the mobile sector a portion of the safety margin, as described further below. [10 ] Ohio has demonstrated that the Cleveland area can maintain the 2015 ozone NAAQS in the 2038 maintenance year with mobile source emissions of 7.72 tons per ozone season day of NO X and 9.92 tons per ozone season day of VOCs. Similarly, the Cleveland area can maintain the 2015 ozone NAAQS in the 2032 interim year with mobile source emissions of 13.16 tons per ozone season day of NO X and 14.49 tons per ozone season day of VOCs. Despite partial allocation of the safety margin, emissions will remain under emission levels in the 2025 attainment year.

The EPA is initiating the adequacy process and proposing to approve the budgets for use to determine transportation conformity in the Cleveland area, because the EPA has determined that the area can maintain attainment of the 2015 ozone NAAQS for the relevant maintenance period with mobile source emissions at the levels of the budgets.

B. What is a safety margin?

A “safety margin” is the amount by which the total projected emissions from all sources of a given pollutant are less than the total emissions that would satisfy the applicable requirement for maintenance. 40 CFR 93.101. As noted in Tables 3 and 4, the emissions in the Cleveland area are projected to have safety margins of 14.63 tons per ozone season day for NO X and 13.17 tons per ozone season day for VOC in 2038 (the difference between emissions in the 2025 attainment year, and projected emissions in the 2038 maintenance year, for all sources in the Cleveland area). Similarly, there is a safety margin of 10.45 tons per ozone season day for NO X and 8.53 tons per ozone season day for VOC in 2032. Even if emissions exceeded projected levels by the full amount of the safety margin, the counties would still demonstrate maintenance since emission levels would equal those in the attainment year.

As shown in Table 5 above, Ohio is allocating a portion of that safety margin to the mobile source sector. Specifically, in 2032, Ohio is allocating 1.72 tons per ozone season day and 1.39 tons per ozone season day of the NO X and VOC safety margins, respectively. In 2038, Ohio is allocating 1.01 tons per ozone season day and 1.29 tons per ozone season day of the NO X and VOC safety margins, respectively. Ohio is not requesting allocation to the budgets of the entire available safety margins reflected in the demonstration of maintenance. In fact, the amount allocated to the budgets represents only a portion of the 2032 and 2038 safety margins. Therefore, even though the State is requesting budgets that exceed the projected onroad mobile source emissions for 2032 and 2038 contained in the demonstration of maintenance, the increase in onroad mobile source emissions that can be considered for transportation conformity purposes is within the safety margins of the ozone maintenance demonstration. Further, once allocated to mobile sources, these safety margins will not be available for use by other sources.

VI. Adjustment of SIP Submittal Deadlines

A. Sixth Circuit Court of Appeals decision in Sierra Club

                v.
                 EPA

As discussed in III., section 107(d)(3)(E) of the CAA contains the criteria for redesignation. CAA section 107(d)(3)(E)(v) specifically requires that “the State containing such area has met all requirements applicable to the area under section [110] of this title and part D of this subchapter.” The EPA's interpretation of that provision since passage of the 1990 CAA Amendments has been that requirements with submission deadlines occurring after the State's submission of its redesignation request are not “applicable” under CAA section 107(d)(3)(E)(v) for purposes of evaluating the approvability of the redesignation.

On May 19, 2023, the EPA redesignated the Detroit area to attainment of the 2015 ozone NAAQS. The EPA relied on its longstanding interpretation of the CAA section 107(d)(3)(E)(v) in finding that Michigan had satisfied that requirement, because the State had met all applicable requirements that were due as of the time of the State's submission requesting redesignation. The EPA's redesignation of the Detroit ozone nonattainment area was challenged, partially based on the argument that the CAA required Michigan to have met all applicable requirements due as of the time the EPA issued the final redesignation, rather than the requirements due as of the time Michigan submitted its redesignation application.

On December 5, 2025, the Sixth Circuit Court of Appeals vacated the EPA's redesignation of the Detroit area. The Court held that Michigan was required to have met all requirements due at the time of the EPA's redesignation action, not just the requirements that had been due as of the time of submittal of the redesignation request. See Sierra Club v. EPA, 161 F.4th 934 (6th Cir. 2025).

B. Proposed Adjustment of Serious SIP Submittal Deadlines

As noted, the EPA's interpretation of CAA section 107(d)(3)(E)(v) has informed State and Federal implementation of redesignations for more than three decades. Preparation of a redesignation request requires many months, and sometimes years, of State resources. Technical information supporting the change in designation must be assembled, including development of appropriate emission inventories and/or modeling, an implementation plan providing for the area's continued maintenance must be prepared, and the request itself must be ( printed page 18369) drafted and assembled. Ohio had already devoted considerable resources towards preparing its request to redesignate the Cleveland nonattainment area to attainment when the 6th Circuit issued its decision. And, understandably, it had done so under the long-standing pre- Sierra Club framework that had governed redesignations and the expectations of what States were required to submit in order for areas to have their redesignation requests granted. Therefore, the redesignation request submitted to the EPA on December 8, 2025, did not address Serious area SIP requirements, because the deadline for those requirements was January 1, 2026, a date which fell after the submission of the State's request.

The EPA is therefore taking these circumstances into account in proposing to adjust the deadline for certain Serious area SIP requirements for the Cleveland area. The Agency has previously made similar adjustments to implementation deadlines in response to an adverse court decision. See 79 FR 31566 (June 2, 2014). In that instance, the EPA had for many years implemented particulate matter standards under subpart 1 of the CAA, and the D.C. Circuit held that the Agency had erred in doing so, and that the CAA required the implementation of those standards to be governed by subpart 4 instead. In response to that adverse decision, rather than find that States were immediately in default of subpart 4 obligations, the EPA established prospective, relatively expedited deadlines for States to comply with any outstanding subpart 4 requirements. See 78 FR 69806, 69809 (Nov. 21, 2013) (proposing a SIP submission deadline of December 31, 2014 on the basis that it “provides a relatively brief but reasonable amount of time for States to ascertain whether and to what extent any additional submissions are needed for a [particulate matter] nonattainment area, and to develop, adopt and submit any such SIPs”). The D.C. Circuit found that the Agency acted within its authority in establishing new deadlines “in the novel circumstances of this case, [where] all affected parties have been long acting on the mistaken assumption that a different framework . . . controls.” Wildearth Guardians v. EPA, 830 F.3d 529, 539 (D.C. Cir. 2016).

In establishing new deadlines in the PM 2.5 rule at issue in Wildearth Guardians, the EPA relied upon its general rulemaking authority under CAA section 301(a), which authorizes the Administrator to promulgate such regulations as are necessary to carry out his functions under the CAA. The Court held that the rule represented “a reasonable exercise of the EPA's gap-filling authority” in that it retained the CAA's attainment deadline for the areas, “even though that date was fast approaching by the time of the Rule's promulgation,” and “[m]oreover, the agency's plan submission deadline . . . was less than two years after the NRDC decision [requiring implementation of the PM 2.5 NAAQS under subpart 4] and some six months after the [final publication of] the Rule.” Id. at 541. The Court noted that the “short timeframe suggests a reasonable effort to expedite compliance with the Subpart 4 framework without imposing unfair obligations on states.” Id.

Here, the EPA is proposing to alter deadlines for reasons similar to the EPA's action establishing new deadlines for PM 2.5 SIPs. Additionally, the EPA has specific authority over reclassified ozone nonattainment areas under CAA section 182(i) to “adjust any applicable deadlines (other than attainment dates) to the extent such adjustment is necessary or appropriate to assure consistency among the required submissions.” The January 1, 2026, Serious area SIP submission deadline applicable to the Cleveland area was established by rule at 40 CFR 51.1402(b)(1)(i). [11 ] As noted in that regulatory provision, the default deadline for reclassified areas applies “unless the Administrator establishes a different deadline in a separate action.”

The EPA is therefore proposing under its statutory and regulatory authority to establish a different Serious SIP submission deadline for the Cleveland area. This one-time adjustment of the Serious area SIP submission deadline for the reclassified Cleveland ozone nonattainment area) is necessary and appropriate to address Ohio's reasonable expectations, based on the existing framework of CAA required submissions since the passage of the 1990 CAA Amendments, that it had prepared a complete and approvable redesignation request prior to the Serious area SIP submittal deadline. This proposed adjustment will allow the State to make any submissions it determines necessary. The EPA proposes to adjust the deadline for Ohio to submit Serious SIP revisions for the Cleveland area to no later than December 5, 2026, one year after the Sixth Circuit's decision.

VII. Enhanced I/M

A. Requirements and Background

CAA section 182(c)(3) requires States with ozone nonattainment areas classified as Serious to implement an Enhanced motor vehicle I/M program. The goal of I/M programs is to identify and ensure repair of high-emitting vehicles operating in nonattainment areas in order to reduce emissions of ozone precursors and support attainment of the NAAQS. [12 ] The CAA generally requires I/M programs for areas across the country that meet certain criteria such as air quality status, population, and/or geographic location. The CAA also directed the EPA to establish minimum performance standards for Enhanced I/M programs. States have flexibility to design their own Basic and Enhanced I/M programs if they can show that their program is as effective as the model program used in the respective performance standard. The EPA's requirements for Enhanced I/M programs are found in 40 CFR part 51, subpart S.

As a result of the Cleveland area's reclassification to Serious effective January 16, 2025 (89 FR 101901), Ohio is required to implement an Enhanced I/M program meeting requirements of CAA section 182(c)(3).

The EPA approved the Cleveland area's I/M program as contained in “I/M Program Rules and Regulations”, Title 3745, Chapter 26 of the Ohio Administrative Code (OAC 3745-26) as part of a state-wide I/M program approval on April 4, 1995, 60 FR 16989, and approved revisions to the program on January 6, 1997, 62 FR 646. OAC 3745-26-12 requires that beginning January 1, 1996, the Ohio EPA Director implement and supervise an Enhanced I/M program to comply with the CAA in the necessary counties of each ozone nonattainment area across the State. Ohio's I/M SIP identifies Cleveland-area counties designated for the area's Enhanced I/M program known as “E-Check”.

B. Ohio's I/M Program Components

Consistent with the I/M regulations at 40 CFR 51.351, a State with an existing I/M program needs to conduct and submit a performance standard modeling analysis as well as make any necessary program revisions as part of their Serious area SIP submission to ensure their I/M program operates at or above the Enhanced I/M performance ( printed page 18370) standard level for the 2015 ozone NAAQS. In addition to passenger vehicles, the State must demonstrate that its Enhanced I/M program includes inspection of on-board diagnostic (OBD) systems for all subject OBD-equipped light-duty vehicles and light-duty trucks, consistent with CAA section 182(c)(3)(C)(vii) and 40 CFR 51.373. In addition, the State needs to demonstrate that it meets the Enhanced I/M requirement to conduct supplemental onroad testing of at least 0.05% of the subject vehicle population. The State must also demonstrate that it meets the biennial performance evaluation reporting requirement for Enhanced I/M programs. Lastly, the State must demonstrate that its Enhanced I/M program waiver repair expenditures meet or exceed the applicable Enhanced I/M minimum expenditure threshold established under 40 CFR 51.360.

The State may determine through the performance standard modeling analysis that an existing SIP-approved program would meet the applicable performance standard for purposes of the 2015 ozone NAAQS without modification. In its December 19, 2025, submittal, Ohio EPA certified that the existing SIP-approved I/M program at OAC 3745-26 meets the Enhanced I/M program requirements of CAA section 182(c)(3) and 40 CFR part 51, subpart S for the Cleveland Serious nonattainment area under the 2015 ozone NAAQS. Our review of Cleveland's Enhanced I/M program demonstration will be discussed in the next section.

C. Evaluation of Ohio's I/M Certification

1. Enhanced I/M Performance Standard

Ohio continues to implement the SIP-approved Enhanced vehicle I/M program in the Cleveland-Akron-Lorain nonattainment area. Ohio utilized the EPA's October 2022 guidance, “Performance Standard Modeling for New and Existing Vehicle Inspection and Maintenance (I/M) Programs Using the MOVES Mobile Source Emissions Model,” to demonstrate that their program operates at or above the Enhanced I/M performance standard. Accordingly, because the Cleveland area is required to implement an Enhanced I/M program for the 2015 ozone NAAQS as a result of its reclassification to Serious effective January 16, 2025 (89 FR 101901, December 17, 2024), Ohio must demonstrate that its existing SIP-approved program operates at or above the Enhanced I/M performance standard specified in 40 CFR 51.351(i).

Ohio conducted an Enhanced I/M performance standard modeling (PSM) analysis comparing emission rates produced by Ohio's existing I/M program with those produced by the Federal model Enhanced I/M program specified in 40 CFR 51.351(i). To meet the Enhanced I/M performance standard, the emission rates produced by the actual I/M program must be equal to or less than those of the Federal model program, within the allowable compliance margin of 0.02 grams per mile (gpm) for VOC and NO X.

The Cleveland area's Serious attainment date is August 3, 2027. Ohio selected analysis year 2026 for its PSM analysis, which corresponds to the ozone season immediately preceding the attainment date and is consistent with the EPA's October 2022 PSM guidance. Ohio conducted the modeling analysis using MOVES5.0.0, which was the most current version of the EPA's mobile source emissions model available when the analysis was initiated.

In consultation with the EPA, Ohio selected Lorain County and Summit County as representative counties for the Cleveland-Akron-Lorain nonattainment area. Lorain County represents the NOACA portion of the area, which includes Cuyahoga, Geauga, Lake, Lorain, and Medina Counties. Summit County represents the AMATS portion of the area, which includes Portage and Summit Counties. This representative-county approach is consistent with the EPA guidance.

| County | Pollutant | OH I/M program VOC emission rate | Enhanced I/M VOC performance standard
benchmark | Enhanced I/M VOC performance standard
benchmark plus allowable buffer | Does existing
program meet

enhanced I/M

performance
standard? |
| --- | --- | --- | --- | --- | --- |
| Lorain | VOC | 0.2631 | 0.2624 | 0.2824 | Yes. |
| | NO X | 0.1103 | 0.1077 | 0.1277 | Yes. |
| Summit | VOC | 0.2169 | 0.2163 | 0.2363 | Yes. |
| | NO X | 0.0967 | 0.0943 | 0.1143 | Yes. |
Table 6 summarizes the comparison between emission rates produced by Ohio's existing Enhanced I/M program and the Federal model Enhanced I/M performance standard benchmark for analysis year 2026. As shown in Table 6, the emission rates produced by Ohio's Enhanced I/M program are within the allowable 0.02 gpm compliance margin of the Federal model Enhanced I/M performance standard benchmark for both VOC and NO X. Therefore, Ohio's modeling results demonstrate that its existing SIP-approved Enhanced I/M program operates at or above the Enhanced I/M performance standard specified in 40 CFR 51.351(i) for the 2015 ozone NAAQS.

Based on our review of Ohio's modeling methodology, input assumptions, and results, the EPA proposes to find that Ohio satisfies the Enhanced I/M performance standard requirements of CAA section 182(c)(3) and 40 CFR part 51, subpart S for the Cleveland Serious ozone nonattainment area under the 2015 ozone NAAQS.

2. Onroad Testing

One of the obligations of an Enhanced I/M program is to perform supplemental onroad testing of in-use vehicles for a small percentage of the area's fleet of motor vehicles. CAA section 182(c)(3)(B)(i) directs the EPA to establish “a performance standard achievable by a program combining emission testing, including onroad emission testing. . .” Additionally, for Enhanced I/M areas, CAA section 182(c)(3)(C)(i) requires States' Enhanced I/M programs to include “onroad testing devices” as a necessary element. CAA requirements for onroad testing devices are established at 40 CFR 51.531(b), which defines onroad testing as “. . . testing of vehicles for conditions impacting the emission of HC, CO, NO X, and/or CO 2 emissions on any road or roadside in the nonattainment area or the I/M program area” and that 0.5% of the subject fleet . . . or 20,000 vehicles, ( printed page 18371) whichever is less, per inspection cycle” must be tested. In its December 19, 2025, submittal, Ohio provided Ohio EPA contract requirements demonstrating that Envirotest, the current inspection contractor, is contractually required to conduct supplemental onroad testing in the Cleveland area consistent with 40 CFR 51.351(b), which requires testing of at least 0.5% of the subject fleet or 20,000 vehicles per inspection cycle, whichever is less. Ohio's submittal provided the E-Check contract indicating that Envirotest currently exceeds the 0.5% onroad testing minimum.

3. Biennial Performance Evaluation

CAA section 182(c)(3)(C) requires that all States subject to Enhanced I/M must “. . . biennially prepare a report to the Administrator which assesses the emission reductions achieved by the program required under this paragraph based on data collected during inspection and repair of vehicles. The methods used to assess the emission reductions shall be those established by the Administrator.” Specific Enhanced I/M biennial program evaluation requirements are established in 40 CFR 51.353. 40 CFR 51.353(c) requires a State to quantify the emission reduction benefits of the program and to determine if the program is meeting the CAA Enhanced I/M requirements on a biennial basis. Further, 40 CFR 51.366(e) requires States to report any changes made in program design, funding, personnel levels, procedures, regulations, and legal authority, and to report any identified weaknesses or problems in the program within the two-year reporting period along with any corrective measures taken to resolve those issues.

Ohio's December 19, 2025, submittal demonstrates that the State meets the CAA requirements for biennial program evaluation in its latest 2023-2024 Ohio E-Check Biennial Report. [13 ] The biennial report was conducted in accordance with the EPA's technical guidance “Guidance on Biennial Performance Evaluation Requirements for Enhanced Vehicle Inspection and Maintenance (I/M) Programs”, EPA-420-B-22-042, December 2022. [14 ] Ohio performed its biennial Enhanced I/M program evaluation using the EPA's MOVES3 mobile source emissions model, which is in accordance with the EPA's technical guidance. Ohio's 2023-2024 biennial program evaluation reported no changes to its program design, funding, personnel levels, procedures, regulations, or legal authority over the reporting time period. Ohio's 2023-2024 biennial program evaluation reported no weaknesses or problems identified over the reporting period. The EPA's review of Ohio's December 19, 2025, submittal finds that Ohio meets the CAA biennial program evaluation requirements for an Enhanced I/M program under the Serious 2015 ozone NAAQS.

4. I/M Test Repair Waivers

40 CFR 51.360 requires States to provide for issuance of I/M test waivers to motorists under certain criteria, provided that the motorist has made repair expenditures that meet the cost thresholds outlined in paragraphs (6) and (7) of the rule. Ohio's December 19, 2025, submittal demonstrates that the State has the authority to issue I/M test waivers to motorists that meet the required cost thresholds consistent with 40 CFR 51.360. Therefore, the EPA's review of Ohio's December 19, 2025, submittal finds that Ohio meets the CAA requirements for Enhanced I/M test repair waivers.

5. Enhanced I/M Program Demonstration Conclusion

Based on our review of Ohio's December 19, 2025, submission, including the performance standard modeling demonstration, onroad testing documentation, biennial evaluation report, and waiver provisions, the EPA proposes to find that Ohio's current SIP-approved Enhanced I/M program satisfies the requirements of CAA section 182(c)(3) and 40 CFR part 51, subpart S for the Cleveland Serious ozone nonattainment area under the 2015 ozone NAAQS.

VIII. Clean Fuel Vehicle Program

CAA section 182(c)(4) requires States with ozone nonattainment areas classified as Serious or higher to submit a SIP revision describing implementation of a CFVP, as described in CAA title II part C (40 CFR 88). CAA section 182(c)(4) included numerical standards for the CFVP that were intended to encourage innovation and reduce emissions for fleets of motor vehicles in certain nonattainment areas as compared to conventionally fueled vehicles available at the time. As originally adopted, those Clean Fuel Fleet standards were substantially more stringent than the standards that applied to vehicles and engines generally. Now that the EPA has begun implementing Tier 3 emission standards in 40 CFR part 86, subpart S, the Clean Fuel Fleet standards are either less stringent than or equivalent to the standards that apply to vehicles and engines generally. On July 29, 2021 (86 FR 34308), the EPA published a final rule in which the EPA determined that vehicles and engines certified to current emission standards under 40 CFR part 86 or 1036 are deemed to also meet the Clean Fuel Fleet standards as Ultra Low-Emission Vehicles. Since vehicle emission standards have only become more stringent since the EPA issued that determination, the CAA section 182(c)(4) CFVP requirements remain satisfied without the need for further action by the State. The currently approved ozone SIP for the Cleveland area meets the Clean Fuel Fleets requirement based on the EPA's June 29, 2021, rulemaking. Ohio demonstrated that a CFVP does not need to be implemented in the Cleveland area. The EPA agrees with Ohio and proposes to find that Ohio meets the Clean Fuel Fleets requirement for Serious ozone areas.

IX. Enhanced Monitoring Program

Section 182(c)(1) of the CAA requires States with nonattainment areas classified serious or higher adopt and implement a program to improve air monitoring for ozone, NO X, and VOC. The EPA initiated the Photochemical Assessment Monitoring Stations (PAMS) program in February 1993 to meet this CAA requirement. The PAMS program required the establishment of an enhanced monitoring network in all ozone nonattainment areas classified as serious, severe, or extreme.

Since that time, the EPA concluded that requiring enhanced monitoring for ozone nonattainment areas classified as moderate or above is appropriate for the purposes of monitoring ambient air quality and better understanding ozone pollution. In the EPA's revision to the ozone standard on October 26, 2015, the EPA relied on the authority provided in sections 103(c), 110(a)(2)(B), 114(a) and 301(a)(1) of the CAA to expand the PAMS applicability to areas other than those that are serious or above ozone nonattainment and substantially revise the PAMS requirements in 40 CFR part 58 appendix D (80 FR 65292). Specifically, this rule required States with moderate and above ozone nonattainment areas to develop and implement an EMP. These plans should detail enhanced ozone and ozone precursor monitoring activities to be performed to better understand area-specific ozone issues.

To meet this requirement, Ohio submitted its Cleveland ozone EMP as part of the 2024-2025 Ohio EPA Air ( printed page 18372) Monitoring Network Plan, which has been approved by the EPA. As stated in their December 19, 2025, submittal, Ohio will continue to meet the CAA 182(c)(1) EMP requirements by including the plan in subsequent Ambient Air Monitoring Network Plans and to update the plan as necessary. These network plans are subject to the EPA's review and approval on an annual basis. Therefore, the EPA is proposing to approve Ohio EPA's certification that the Cleveland area has satisfied the EMP requirements of the CAA section 182(c)(1) for the 2015 ozone NAAQS.

X. What action is the EPA taking?

The EPA will not take final action to redesignate the Cleveland area to attainment if the EPA fails to finalize the CDD or if the design value of a monitoring site in the area violates the NAAQS prior to final approval of the redesignation. The EPA is proposing to determine that, with the EPA's approval of the CDD and Ohio's moderate RACT submittals, the Cleveland area will have met the requirements for redesignation under section 107(d)(3)(E) of the CAA. The EPA is thus proposing to change the legal designation of the Cleveland area from nonattainment to attainment for the 2015 ozone NAAQS in accordance with Ohio EPA's December 8, 2025, request. The EPA is proposing to approve the State's plan for maintaining the 2015 ozone NAAQS in the Cleveland area through 2038 (such approval being one of the CAA criteria for redesignation to attainment status). As part of the maintenance plan, the EPA is initiating the adequacy process and proposing to approve the newly established 2032 and 2038 motor vehicle emissions budgets for the Cleveland area. The EPA is also proposing to adjust the deadline for Ohio to submit Serious SIP revisions for the Cleveland area to no later than December 5, 2026. Finally, pursuant to section 110 and part D of the CAA, the EPA is proposing to approve the Enhanced I/M certification, CFVP certification, and EMP certification SIP revisions submitted by Ohio EPA on December 19, 2025, and supplemented on January 12, 2026.

XI. Statutory and Executive Order Reviews

Under the CAA, redesignation of an area to attainment and the accompanying approval of a maintenance plan under section 107(d)(3)(E) are actions that affect the status of a geographical area and do not impose any additional regulatory requirements on sources beyond those imposed by State law. A redesignation to attainment does not in and of itself create any new requirements, but rather results in the applicability of requirements contained in the CAA for areas that have been redesignated to attainment. Moreover, the Administrator is required to approve a SIP submission that complies with the provisions of the CAA and applicable Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in reviewing SIP submissions, the EPA's role is to approve State choices, provided that they meet the criteria of the CAA. Accordingly, the proposed actions to approve Ohio's SIP submissions merely approve State law as meeting Federal requirements and do not impose additional requirements beyond those imposed by State law. For these reasons, this action:

• Is not a significant regulatory action subject to review by the Office of Management and Budget under Executive Order 12866 (58 FR 51735, October 4, 1993);
• Is not subject to Executive Order 14192 (90 FR 9065, February 6, 2025) because SIP actions are exempt from review under Executive Order 12866;
• Does not impose an information collection burden under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
• Is certified as not having a significant economic impact on a substantial number of small entities under the Regulatory Flexibility Act (5 U.S.C. 601 et seq.);
• Does not contain any unfunded mandate or significantly or uniquely affect small governments, as described in the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4);
• Does not have federalism implications as specified in Executive Order 13132 (64 FR 43255, August 10, 1999);
• Is not subject to Executive Order 13045 (62 FR 19885, April 23, 1997) because it approves a State program;
• Is not a significant regulatory action subject to Executive Order 13211 (66 FR 28355, May 22, 2001); and
• Is not subject to requirements of section 12(d) of the National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 note) because application of those requirements would be inconsistent with the CAA. In addition, the SIP is not approved to apply on any Indian reservation land or in any other area where the EPA or an Indian Tribe has demonstrated that a Tribe has jurisdiction. In those areas of Indian country, the rulemaking does not have Tribal implications and will not impose substantial direct costs on Tribal governments or preempt Tribal law as specified by Executive Order 13175 (65 FR 67249, November 9, 2000).

List of Subjects

40 CFR Part 52

• Environmental protection
• Air pollution control
• Incorporation by reference
• Intergovernmental relations
• Nitrogen dioxide
• Ozone
• Reporting and recordkeeping requirements
• Volatile organic compounds

40 CFR Part 81

• Environmental protection
• Air pollution control
• National parks
• Wilderness areas Dated: March 30, 2026.

Anne Vogel,

Regional Administrator, Region 5.

Footnotes

1.

                     The ozone season is defined by State in [40 CFR 58](https://www.ecfr.gov/current/title-40/part-58), appendix D. The ozone season for Ohio is March-October. 
                    See [80 FR 65292](https://www.federalregister.gov/citation/80-FR-65292), [65466](https://www.federalregister.gov/citation/80-FR-65466) through [65467](https://www.federalregister.gov/citation/80-FR-65467) (October 26, 2015).

Back to Citation 2.

                     The monitor ozone design value for the monitor with the highest 3-year averaged concentration.

Back to Citation 3.

                     CAA section 176(c)(4)(E) requires States to submit revisions to their SIPs to reflect certain Federal criteria and procedures for determining transportation conformity. Transportation conformity SIPs are different from SIPs requiring the development of motor vehicle emissions budgets, such as control strategy SIPs and maintenance plans.

Back to Citation 4. https://www.epa.gov/​sites/​default/​files/​2021-02/​documents/​nei2017​tsd​full_​jan2021.pdf and https://www.epa.gov/​air-emissions-modeling/​2022v1-emissions-modeling-platform-technical-support-document.

Back to Citation 5.

                     EPA, Technical Support Document (TSD): Preparation of Emission Inventories for the 2017 North American Emissions Modeling Platform, February 2022, *[https://www.epa.gov/​system/​files/​documents/​2022-03/​2017_​emismod_​tsd_​february2022_​0.pdf](https://www.epa.gov/system/files/documents/2022-03/2017_emismod_tsd_february2022_0.pdf)*.

Back to Citation 6.

                     U.S. Census Bureau. “EMPLOYMENT STATUS.” *American Community Survey, Table S2301*.

Back to Citation 7.

                     U.S. Bureau of Economic Analysis, Total Gross Domestic Product for Cleveland-Elyria, OH (MSA) [NGMP17460], retrieved from FRED, Federal Reserve Bank of St. Louis; *[https://fred.stlouisfed.org/​series/​NGMP17460](https://fred.stlouisfed.org/series/NGMP17460),* November 25, 2025.

Back to Citation 8.

                     The submitted report of additional information and analysis may include, but is not limited to, the following: ozone and ozone precursor concentration data from nearby monitoring sites, surface and upper air meteorology analyses, analysis of satellite imagery, Hazard Mapping System (HMS) smoke layer maps, HYSPLIT forward and back trajectory analyses, analysis of UW's GAM statistical modeling results, analysis of meteorology-adjusted ozone trends data, any other event-specific analyses necessary to determine the cause(s) of the monitored ozone concentrations.

Back to Citation 9.

                     See [40 CFR 93.118(f)(2)](https://www.ecfr.gov/current/title-40/section-93.118#p-93.118(f)(2)) for requirements associated with making adequacy findings through rulemaking on a submitted SIP.

Back to Citation 10.

                     Allocation of a safety margin to an area's motor vehicle emissions budgets is provided for by the transportation conformity rule. 
                    See [40 CFR 93.124(a)](https://www.ecfr.gov/current/title-40/section-93.124#p-93.124(a)).

Back to Citation 11. 40 CFR 51.1402(b)(1)(i) establishes the SIP revision deadline for reclassified areas as 18 months after the effective date of the relevant reclassification or January 1 of the attainment year, whichever is earlier. In this case, January 1, 2026, was the earlier date.

Back to Citation 12.

                     For more information, see *Overview of Vehicle Inspection and Maintenance (I/M) Programs* (EPA-420-F-21-067, October 2021) at *[https://nepis.epa.gov/​Exe/​ZyPDF.cgi?​Dockey=​P1013CC0.pdf](https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P1013CC0.pdf).*

Back to Citation 13. https://dam.assets.ohio.gov/​image/​upload/​epa.ohio.gov/​Portals/​27/​echeck/​docs/​2023-Biennial-Report_​Final.pdf.

Back to Citation 14. https://www.epa.gov/​system/​files/​documents/​2022-12/​420b22042.pdf.

Back to Citation [FR Doc. 2026-06943 Filed 4-9-26; 8:45 am]

BILLING CODE 6560-50-P

Published Document: 2026-06943 (91 FR 18355)