Ozone Implementation Regulatory Actions
The Clean Air Act requires EPA to set National Ambient Air Quality Standards (NAAQS) for six criteria pollutants; ozone pollution is one of these. EPA works with partners at state, local, and tribal air quality agencies to meet these standards.
The following list provides a collection of rules and guidance documents for implementation the more recent ozone standards:
- Ozone (2015)
- Ozone (2008)
- To find implementation information and guidance documents see Ozone (1997)
- General Preamble for the Implementation of Title 1 of the Clean Air Act Amendments of 1990
To see a table of all of the Ozone NAAQS visit our Ozone National Ambient Air Quality Standards (NAAQS) page.
Proposed Ozone Reclassification State Implementation Plan Rule
June 9, 2026 - U.S. Environmental Protection Agency (EPA) proposed revisions to portions of the Biden EPA's January 2025 final rule, which required states to keep certain State Implementation Plan (SIP) requirements tied to an area's prior ozone nonattainment classification under the National Ambient Air Quality Standards (NAAQS), even after that area had been reclassified.
SIP requirements are applied to areas designated as nonattainment for the ozone NAAQS. The Trump EPA is proposing to make it so that an area’s current ozone classification, not a previous one, determines the applicable SIP requirements. This proposed change is consistent with the CAA that states an area can only be subject to a single classification at a given time. If finalized, EPA’s state, local, and Tribal air regulatory partners will be given renewed flexibility to better tailor their air quality strategies to current conditions, enhancing protections for human health and the environment, while reducing administrative confusion.
This proposed rulemaking would be applicable to all past and future reclassifications associated with the 2008, 2015, and any future ozone NAAQS. EPA is not proposing to reconsider any of the SIP submittal or implementation deadlines established in the January 2025 rulemaking.
EPA will hold a 30-day public comment period.
- Ozone Reclassification State Implementation Plan Proposed Rule
- Fact Sheet - Ozone Reclassification State Implementation Plan Proposed Rule (pdf)
Final State Implementation Plan Submittal Deadlines and Implementation Requirements for Reclassified Nonattainment Areas Under the Ozone National Ambient Air Quality Standards
September 15, 2025 – EPA is announcing that the subject of the reconsideration of the 2025 State Implementation Plan Submittal Deadlines and Implementation Requirements for Reclassified Nonattainment Areas Under the Ozone National Ambient Air Quality Standards (originally announced on June 3, 2025) will be the “leftover” SIPs requirements. As explained in the proposed rule, these are unresolved requirements applicable to the former classification after reclassification. EPA will propose to reconsider these requirements, which are codified at 40 CFR 51.1403(a)(1).
June 3, 2025 - EPA is announcing reconsideration of the 2025 State Implementation Plan Submittal Deadlines and Implementation Requirements for Reclassified Nonattainment Areas Under the Ozone National Ambient Air Quality Standards. EPA will issue a proposal in the Federal Register in the coming months, soliciting public comments.
January 3, 2025 - EPA is issuing a final rule that will streamline state planning and air quality protection requirements under the current and any future ozone National Ambient Air Quality Standards (NAAQS). This action will protect public health by clarifying steps needed to assure air quality standards are attained and maintained as required by the Clean Air Act (CAA). Specifically, EPA is establishing:
- universal default deadlines for submission of state implementation plan (SIP) revisions and for implementation of relevant control requirements that will apply for reclassified Moderate, Serious, and Severe nonattainment areas.
- that, following reclassification, a state is no longer required to submit SIP revisions addressing certain requirements related to a nonattainment area’s prior classification, referred to as “leftover” SIP requirements.
EPA is not reclassifying any ozone nonattainment areas as part of this action.
September 20, 2024: