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 This website is no longer updated and links to external websites and some internal pages may not work.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

Policy for Establishing Separate Air Quality Designations for Areas of Indian Country Memorandum

This 2011 memorandum provides EPA's policy regarding designating areas of Indian country separately from adjacent areas for the National Ambient Air Quality Standards (NAAQS), when requested by the relevant tribe for a particular area of Indian country (as defined at 18 U.S.C. § 1151).

For more information on the NAAQS, visit the 2008 Ozone NAAQS page.

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