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 This website is no longer updated and links to external websites and some internal pages may not work.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

Regulations for Emissions from Vehicles and Engines

Final Rule for Control of Air Pollution From Aircraft and Aircraft Engines; Emission Standards and Test Procedures

On this page:

Rule Summary

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

EPA adopted emission standards and related provisions for aircraft gas turbine engines with rated thrusts greater than 26.7 kilonewtons. These engines are used primarily on commercial passenger and freight aircraft. The requirements were previously adopted by the International Civil Aviation Organization (ICAO). Included in the rule are two new tiers of more stringent emission standards for oxides of nitrogen (NOx). These are referred to as Tier 6 standards and Tier 8 standards. The Tier 6 standards become effective for newly-manufactured aircraft engines beginning in 2013.

Rule History

Additional Resources

Fact Sheets

Regulations for Emissions from Vehicles and Engines Home