🌬️EPA Proposes Revisions to Missouri Air Quality Standards
The Environmental Protection Agency (EPA) is proposing to approve revisions to the Missouri State Implementation Plan (SIP) related to Definitions and Common Reference Tables used in Missouri rules. EPA has also previously approved this rule as part of the air planning and permitting program. Some of the definitions are associated with those programs, even though many of the definitions pertain only to the SIP. These revisions do not impact the stringency of the SIP or have an adverse effect on air quality. The EPA's proposed approval of this rule revision is being done in accordance with the requirements of the Clean Air Act (CAA).
Learn More🌬️EPA Air Plan Approval
The Environmental Protection Agency (EPA) is updating the regulatory materials that are incorporated by reference into the Idaho State Implementation Plan (SIP). The EPA is also notifying the public of corrections and clarifying changes in the Code of Federal Regulations tables that identify the regulatory materials incorporated by reference into the Idaho SIP. This update affects the materials that are available for public inspection at the National Archives and Records Administration and the EPA Region 10 Office.
Learn More🌍Implications of New Air Quality Regulations for San Joaquin Valley
The Environmental Protection Agency (EPA) is proposing to approve the "2023 Maintenance Plan and Redesignation Request for the Revoked 1-Hour Ozone Standard" ("San Joaquin Valley Maintenance Plan" or "Plan") as a revision to the state implementation plan (SIP) for the State of California. The San Joaquin Valley Maintenance Plan includes, among other elements, an emissions inventory consistent with attainment and contingency provisions. The EPA is also proposing to find that the State of California's request to redesignate the San Joaquin Valley area from nonattainment to attainment for the revoked 1979 1-hour national ambient air quality standard (NAAQS or "standard") for ozone ("1979 ozone NAAQS," "1-hour ozone NAAQS," or "1-hour ozone standard") meets all the Clean Air Act (CAA or "the Act") criteria for redesignation. Therefore, the EPA is proposing to terminate all anti-backsliding obligations for the San Joaquin Valley area for the revoked 1-hour ozone NAAQS.
Learn More🌫️Air Plan Approval in Texas and Oklahoma
The Environmental Protection Agency (EPA) is extending the comment period for the proposed rule "Air Plan Approval; Texas and Oklahoma; Texas Regional Haze Plans for the First and Second Implementation Periods and Five-Year Progress Report; Oklahoma Regional Haze Plan for the First Implementation Period" that was published on May 23, 2025. The proposal provided for a public comment period ending June 23, 2025. The EPA is extending the comment period to July 23, 2025.
Learn More🌫️Missouri's St. Louis Area Reclassified as Serious Ozone Nonattainment
The Environmental Protection Agency (EPA) is accepting comment on a determination that the Missouri portion of the St. Louis, MO-IL bi-state nonattainment area failed to attain the 2015 8-hour ozone National Ambient Air Quality Standards (NAAQS) by the applicable attainment date. The effect of failing to attain by the applicable attainment date is that the area is reclassified by operation of law to "Serious" nonattainment for the 2015 ozone NAAQS. On November 25, 2024, the EPA published a final action in the Federal Register which determined that the St. Louis area failed to attain the 2015 ozone NAAQS by the Moderate area attainment date. That action also reclassified the area to Serious by operation of law with an effective date of December 31, 2024. On January 24, 2025, the EPA received a petition for reconsideration of that final action from the State of Missouri. On March 5, 2025, EPA Region 7 granted the petition for reconsideration and stated our intention to undergo a notice and comment rulemaking. Therefore, the EPA is accepting comment on the determination that the St. Louis area failed to attain by the attainment date. The Illinois portion of the St. Louis, MO-IL bi-state area is addressed separately.
Learn More🌫️EPA Proposes Approval of Michigan's Regional Haze Implementation Plan
The Environmental Protection Agency (EPA) is proposing to approve the Regional Haze State Implementation Plan (SIP) revision submitted by the Michigan Department of Environment, Great Lakes, and Energy (EGLE) on August 23, 2021, and supplemented on April 3, 2025, as satisfying applicable requirements under the Clean Air Act (CAA) and EPA's Regional Haze Rule (RHR) for the program's second implementation period. EGLE's SIP submission addresses the requirement that States must periodically revise their long-term strategies for making reasonable progress towards the national goal of preventing any future, and remedying any existing, anthropogenic impairment of visibility, including regional haze, in mandatory Class I Federal areas. The SIP submission also addresses other applicable requirements for the second implementation period of the regional haze program. EPA is taking this action pursuant to sections 110 and 169A of the CAA.
Learn More🌫️EPA Proposes Air Quality Regulation Approvals for Colorado Businesses
The Environmental Protection Agency (EPA) is proposing to approve state implementation plan (SIP) submittals under the Clean Air Act (CAA) that address Reasonably Available Control Technology (RACT) requirements for the 2008 ozone National Ambient Air Quality Standards (NAAQS) for the Denver Metro/North Front Range (DMNFR) ozone nonattainment area. The requirements at issue relate to the area's previous Serious nonattainment classification. The EPA is proposing approval of the RACT SIP submittals, proposing to find that the State has met the applicable CAA requirements for Serious area RACT, and proposing that the State has addressed EPA's prior disapproval concerning specific RACT determinations. In this issue of the Federal Register the EPA is concurrently making an interim final determination to defer application of CAA sanctions associated with the prior disapproval. The EPA is taking this action pursuant to the CAA.
Learn More🌫️EPA Defers Sanctions in Colorado Ozone Nonattainment Area
In the Proposed Rules section of this Federal Register, EPA is proposing approval of portions of State Implementation Plan (SIP) submissions from the State of Colorado dated June 26, 2023, May 23, 2024, May 30, 2024, and April 2, 2025. The submissions relate to Colorado Air Quality Control Commission Regulation Number 7 (Reg. 7) and Regulation Number 26 (Reg. 26), and address Colorado's SIP obligations for the Reasonably Available Control Technology (RACT) Serious ozone nonattainment area requirement for the 2008 ozone National Ambient Air Quality Standard (NAAQS). In this action, the EPA is making an interim final determination based on that proposed approval. The effect of this interim final determination is that the imposition of sanctions that were triggered by the EPA's December 8, 2023 disapproval are now deferred. Although this action is effective on publication, the EPA will take comment on this interim final determination.
Learn More🌫️California Regional Haze Plan Approval
The Environmental Protection Agency (EPA) is proposing to approve the regional haze state implementation plan (SIP) revision submitted by California on August 9, 2022 (hereinafter the "2022 California Regional Haze Plan" or "the Plan"), under the Clean Air Act (CAA) and the EPA's Regional Haze Rule for the program's second implementation period. California's SIP submission addresses the requirement that states must periodically revise their long-term strategies for making reasonable progress towards the national goal of preventing any future, and remedying any existing, anthropogenic impairment of visibility, including regional haze, in mandatory Class I Federal areas. The SIP submission also addresses other applicable requirements for the second implementation period of the regional haze program. The EPA is proposing this action pursuant to CAA sections 110 and 169A. The EPA is also withdrawing its previous proposed rule to partially approve and partially disapprove California's regional haze SIP revision as published in the Federal Register on December 19, 2024.
Learn More🚗Delaware's EPA Proposal for Vehicle Emissions Inspection Program
The Environmental Protection Agency (EPA) is proposing to approve a state implementation plan (SIP) revision submitted by the State of Delaware. This SIP revision addresses Clean Air Act (CAA) requirements for the enactment of a Basic vehicle emissions inspection and maintenance (I/M) program for the Delaware portion (i.e., New Castle County) of the Philadelphia-Wilmington-Atlantic City, Pa-NJ-MD- DE Nonattainment Area (Philadelphia NAA) for the 2015 8-hour ozone National Ambient Air Quality Standards (NAAQS).
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