SUPPLEMENTARY INFORMATION:

Throughout this document, “we,” “us,” and “our” refer to the EPA.

Table of Contents

I. Summary of the Proposed Action

II. Public Comment

III. Final Action

IV. Statutory and Executive Order Reviews

I. Summary of the Proposed Action

On May 14, 2026, the EPA proposed to determine, based on complete (or otherwise validated), quality-assured, and certified data, meeting the requirements of 40 CFR part 50, appendix N for 2023 through 2025, that the Portola PM_2.5 nonattainment area attained the 2012 annual PM_2.5 NAAQS by its December 31, 2025 attainment date.^[1]

In accordance with 40 CFR 51.1015, we also proposed to issue a CDD for the Portola PM_2.5 nonattainment area for the 2012 annual PM_2.5 NAAQS based on the 2023-2025 data.^[2]

The EPA's proposal explained that if we were to finalize the CDD, the requirements for the area to submit attainment planning provisions to meet the requirements for an attainment plan for the 2012 annual PM_2.5 NAAQS, including an attainment demonstration, reasonable further progress plan, quantitative milestones, quantitative milestone reports, and contingency measures, would be suspended until such time as: (1) the area is redesignated to attainment, after which such requirements are permanently discharged; or (2) the EPA determines that the area has re-violated the PM_2.5 NAAQS, at which time the state shall submit such attainment plan elements for the Serious nonattainment area by a future date to be determined by the EPA and announced through publication in the Federal Register at the time the EPA determines the area is violating the 2012 PM_2.5 NAAQS.^[3] The requirements to submit emissions inventories, best available control measures, including control technologies, and a nonattainment new source review permitting program for the Serious nonattainment area will remain in effect.

Finally, the EPA's proposal explained that the CDD does not constitute a redesignation to attainment. The Portola PM_2.5 nonattainment area will remain designated nonattainment for the 2012 annual PM_2.5 NAAQS until such time as the EPA determines, pursuant to sections 107 and 175A of the Clean Air Act (CAA), that the Portola PM_2.5 nonattainment area meets the CAA requirements for redesignation to attainment, including an approved maintenance plan showing that the area will continue to meet the 1997 annual PM_2.5 NAAQS for 10 years.^[4]

Please see our May 14, 2026 proposed rulemaking for additional background and a detailed explanation of the rationale for our proposed action.^[5]

II. Public Comment

The public comment period for the proposed rulemaking opened on May 14, 2026,^[6] the date of its publication in the Federal Register , and closed on June 15, 2026. During this period, the EPA received one comment submission that discussed diesel generator exhaust associated with data centers around the nation. As this action only concerns the Portola PM_2.5 nonattainment Area, and because there are no data centers in this area, this comment is not germane to our action and does not require a response. The comment is included in the docket for this action.

III. Final Action

For the reasons discussed in detail in our proposed action, the EPA is finalizing our determination that the Portola PM_2.5 nonattainment area has attained the 2012 annual PM_2.5 NAAQS by the December 31, 2025 attainment date, based on complete, quality-assured, and certified ambient air quality monitoring data for the 2023-2025 monitoring period.^[7] The EPA is taking this final action pursuant to CAA section 179(c)(1).

Preliminary data available in the EPA's Air Quality System (AQS) for 2026 (January through March) indicate that the Portola nonattainment area continues to show concentrations consistent with attainment of the 2012 annual PM_2.5 NAAQS; ^[8] therefore, as provided in 40 CFR 51.1015, we are also finalizing a CDD. Consequently, the requirements for the state to submit any SIP revisions related to attainment of the 2012 annual PM_2.5 NAAQS for this ( printed page 52250) area, including an attainment demonstration, reasonable further progress plan, quantitative milestones, quantitative milestone reports, and contingency measures, will be suspended for so long as the area continues to attain this NAAQS. This final determination that the Portola nonattainment area has attained the 2012 annual PM_2.5 NAAQS does not constitute a redesignation of the area to attainment. The designation status of the Portola nonattainment area will remain “Serious” nonattainment for the 2012 annual PM_2.5 NAAQS until such time as the EPA determines, pursuant to sections 107 and 175A of the CAA, that the area meets the CAA requirements for redesignation to attainment, including an approved maintenance plan showing that the area will continue to meet the standard for 10 years.

IV. Statutory and Executive Order Reviews

Additional information about these statutes and Executive Orders can be found at www.epa.gov/​laws-regulations/​laws-and-executive-orders.

A. Executive Order 12866: Regulatory Planning and Review and Executive Order 13563: Improving Regulation and Regulatory Review

This action is not a significant regulatory action and was therefore not submitted to the Office of Management and Budget (OMB) for review.

B. Executive Order 14192: Unleashing Prosperity Through Deregulation

This action is not an Executive Order 14192 regulatory action because this action is not significant under Executive Order 12866.

C. Paperwork Reduction Act (PRA)

This action does not impose an information collection burden under the PRA because this action does not impose additional requirements beyond those imposed by state law.

D. Regulatory Flexibility Act (RFA)

I certify that this action will not have a significant economic impact on a substantial number of small entities under the RFA. This action will not impose any requirements on small entities beyond those imposed by state law.

E. Unfunded Mandates Reform Act (UMRA)

This action does not contain any unfunded mandate as described in UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect small governments. This action does not impose additional requirements beyond those imposed by state law. Accordingly, no additional costs to state, local, or Tribal governments, or to the private sector, will result from this action.

F. Executive Order 13132: Federalism

This action does not have federalism implications. It will not have substantial direct effects on the states, on the relationship between the national government and the states, or on the distribution of power and responsibilities among the various levels of government.

G. Executive Order 13175: Coordination With Indian Tribal Governments

This action does not have Tribal implications as specified in Executive Order 13175. As there are no federally recognized Tribes within the Portola nonattainment area,^[9] the final determination of attainment by the attainment date and CDD do not apply to Tribal areas, and the final rule would not impose a burden on Indian reservation lands or other areas where the EPA or an Indian Tribe has demonstrated that a Tribe has jurisdiction within the Portola nonattainment area. Thus, this final rule 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.

H. Executive Order 13045: Protection of Children From Environmental Health Risks and Safety Risks

The EPA interprets Executive Order 13045 as applying only to those regulatory actions that concern environmental health or safety risks that the EPA has reason to believe may disproportionately affect children, per the definition of “covered regulatory action” in section 2-202 of the Executive Order. This action is not subject to Executive Order 13045 because it does not concern an environmental health risk or safety risk.

I. Executive Order 13211: Actions That Significantly Affect Energy Supply, Distribution, or Use

This action is not subject to Executive Order 13211, because it is not a significant regulatory action under Executive Order 12866.

J. National Technology Transfer and Advancement Act (NTTAA)

Section 12(d) of the NTTAA directs the EPA to use voluntary consensus standards in its regulatory activities unless to do so would be inconsistent with applicable law or otherwise impractical. The EPA believes that this action is not subject to the requirements of section 12(d) of the NTTAA because application of those requirements would be inconsistent with the CAA.

K. Congressional Review Act (CRA)

This action is subject to the CRA and the EPA will submit a rule report to each House of the Congress and to the Comptroller General of the United States. This action is not a “major rule” as defined by 5 U.S.C. 804(2).

L. Petitions for Judicial Review

Under section 307(b)(1) of the CAA, petitions for judicial review of this action must be filed in the United States Court of Appeals for the appropriate circuit by October 13, 2026. Filing a petition for reconsideration by the Administrator of this final rule does not affect the finality of this rule for the purposes of judicial review, nor does it extend the time within which a petition for judicial review may be filed, and shall not postpone the effectiveness of such rule or action. This action may not be challenged later in proceedings to enforce its requirements (see section 307(b)(2)).

For the reasons stated in the preamble, the Environmental Protection Agency amends part 52, chapter I, title 40 of the Code of Federal Regulations as follows:

91 FR 52249