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 This website is no longer updated and links to external websites and some internal pages may not work.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

Air Emissions Inventories

Where is more information available about emissions estimation methods used by the EPA?

For criteria air pollutants and precursors as well as for hazardous air pollutants, the methods are described in the technical support document (TSD) for the latest National Emissions Inventory (NEI) available from the main NEI page.

For greenhouse gas emissions, you can find greenhouse gas inventory methods from the latest “Inventory of U.S. Greenhouse Gas Emissions and Sinks,” which is available on the Sources of Greenhouse Gas Emissions page.