Environmental Protection Agency
The Environmental Protection Agency (EPA) is proposing to approve revisions to the Arizona state implementation plan (SIP) for attaining the 1971 and 2010 sulfur dioxide (SO<INF>2</INF>) national ambient air quality standards (NAAQS or "standards") in the Hayden SO<INF>2</INF> nonattainment area. These SIP revisions, collectively referred to as the "Hayden SO<INF>2</INF> Plan" or "Plan," include Arizona's attainment demonstration and other elements required under Clean Air Act (CAA or "Act") sections 110, 172, 191, and 192. In addition to an attainment demonstration, the revisions address the requirements for meeting reasonable further progress (RFP) toward attainment of the NAAQS, reasonably available control measures and reasonably available control technology (RACM/RACT), base-year and projection-year emissions inventories, nonattainment new source review (NSR), emissions limitations necessary to provide for attainment, and contingency measures. The EPA is proposing to approve the SIP revisions as meeting the CAA requirements. This action is being taken under the CAA. We are taking comments on this proposal and plan to follow with a final action.
Document Headings Document headings vary by document type but may contain the following: the agency or agencies that issued and signed a document the number of the CFR title and the number of each part the document amends, proposes to amend, or is directly related to the agency docket number / agency internal file number the RIN which identifies each regulatory action listed in the Unified Agenda of Federal Regulatory and Deregulatory Actions See the Document Drafting Handbook for more details. Environmental Protection Agency 40 CFR Part 52 [EPA-R09-OAR-2025-3821; FRL-13144-01-R9] AGENCY: Environmental Protection Agency (EPA). ACTION: Proposed rule. SUMMARY: The Environmental Protection Agency (EPA) is proposing to approve revisions to the Arizona state implementation plan (SIP) for attaining the 1971 and 2010 sulfur dioxide (SO 2 ) national ambient air quality standards (NAAQS or “standards”) in the Hayden SO 2 nonattainment area. These SIP revisions, collectively referred to as the “Hayden SO 2 Plan” or “Plan,” include Arizona's attainment demonstration and other elements required under Clean Air Act (CAA or “Act”) sections 110, 172, 191, and 192. In addition to an attainment demonstration, the revisions address the requirements for meeting reasonable further progress (RFP) toward attainment of the NAAQS, reasonably available control measures and reasonably available control technology (RACM/RACT), base-year and projection-year emissions inventories, nonattainment new source review (NSR), emissions limitations necessary to provide for attainment, and contingency measures. The EPA is proposing to approve the SIP revisions as meeting the CAA requirements. This action is being taken under the CAA. We are taking comments on this proposal and plan to follow with a final action. DATES: Comments must be received on or before April 3, 2026. ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-OAR-2025-3821, a…
Citation: 91 FR 10531
