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 This website is no longer updated and links to external websites and some internal pages may not work.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

Air Emissions Inventory Guidance for Implementation of Ozone and Particulate Matter NAAQS and Regional Haze Regulations

This document provides guidance on how to develop emission inventories to meet State Implementation Plan (SIP) requirements for complying with the 8-hour ozone national ambient air quality standard (NAAQS), the revised particulate matter (PM) NAAQS, and the regional haze regulations. It is intended for use by the EPA Regional Offices; State, local and Tribal air quality management authorities; and the general public. The guidance is designed to implement national policy on these issues.

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