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 This website is no longer updated and links to external websites and some internal pages may not work.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 »

Clean Air Markets

Considerations for Identifying Maintenance Receptors Memo

This memo presents information that states may consider as they evaluate the status of monitoring sites that the Environmental Protection Agency (EPA) identified as potential maintenance receptors with respect to the 2015 ozone National Ambient Air Quality Standards (NAAQS) based on EPA’s 2023 modeling. States may use this information when developing state implementation plans (SIPs) for the 2015 ozone NAAQS addressing the good neighbor provision in Clean Air Act (CAA) section 110(a)(2)(D)(i)(I).

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