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Under the Clean Air Act, EPA is required to review and if appropriate revise the air quality criteria and primary (health-based) and secondary (welfare-based) national ambient air quality standards (NAAQS) every 5 years. On December 31, 2020, EPA published a final decision in the last review of the air quality criteria and the primary and secondary ozone NAAQS. In 2021 EPA initiated a reconsideration of the 2020 decision, seeking and receiving advice from the Clean Air Scientific Advisory Committee (CASAC) and a newly-constituted expert ozone panel. After carefully considering this advice, EPA has incorporated the reconsideration into a new review of the ozone NAAQS and the underlying air quality criteria. The new review will include the preparation of an Integrated Review Plan, an Integrated Science Assessment, and, as warranted, a Risk/Exposure Assessment, and also a Policy Assessment by EPA, with opportunities for review by EPA's CASAC and the public. Opportunities for public participation in the development of these assessments include through the offering of comments to the CASAC at public CASAC meetings and directly to the EPA. These assessments will inform the Administrator's proposed decision as to whether to retain or revise the current standards. This proposed decision will be published in the Federal Register and announced on EPA’s website, with opportunity provided for public participation, such as submission of comments to the rulemaking docket and public hearings. Additionally, opportunity is provided for Tribal consultation. The Administrator's final decisions will take into consideration these documents, CASAC advice, and public comment on the proposed decision.