An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

Ground-level Ozone Pollution

Procedures for Processing Requests to Redesignate Areas to Attainment

This memorandum consolidates EPA's guidance regarding the processing of requests for redesignation of nonattainment areas to attainment for ozone (O3), carbon monoxide (CO), particulate matter (PM), sulfur dioxide (SO2), nitrogen dioxide (NO2), and lead (Pb). Regional offices should use this guidance as a general framework for drafting Federal Register notices pertaining to redesignation requests.

You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.