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 This website is no longer updated and links to external websites and some internal pages may not work.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

Ozone Designations

2015 Ozone Standards - EPA Intended Area Designations for Other Tribes

The letters below summarize EPA's intended designations for tribes that did not submit recommendations to EPA but may be potentially impacted by a nonattainment designation in the surrounding area, and for tribes with Treatment as a State status for Clean Air Act section 107(d).  

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