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 This website is no longer updated and links to external websites and some internal pages may not work.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

Fact Sheet: Final CSAPR Close-Out

Fact Sheet for the Final Determination Regarding Good Neighbor Obligations for the 2008 Ozone National Ambient Air Quality Standard (CSAPR Close‐Out).

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