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AP-42 Emissions Factors (WebFIRE)

Published by U.S. EPA Office of Air and Radiation (OAR) - Office of Air Quality Planning and Standards (OAQPS) | U.S. Environmental Protection Agency | Catalog Last Checked: May 01, 2026 at 06:06 PM | Dataset Last Updated: January 01, 2014
Emissions factors have long been the fundamental tool in developing national, regional, state, and local emissions inventories for air quality management decisions and in developing emissions control strategies. More recently, emissions factors have been applied in determining site-specific applicability and emissions limitations in operating permits by federal, state, local, and tribal agencies, consultants, and industry. AP-42 is a compendium of EPA recommended emissions factors.

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