Visit for the latest Coronavirus Disease (COVID-19) updates.

You are here

In This Section:

National Emissions Inventory


The Environmental Protection Agency's (EPA) National Emissions Inventory (NEI) database contains information about sources that emit criteria air pollutants and their precursors, and hazardous air pollutants. The database includes estimates of annual air pollutant emissions from point, nonpoint, and mobile sources in the 50 states the District of Columbia, and Puerto Rico. EPA collects information about sources and releases an updated version of the NEI database every three years.

Environmental Protection Agency
Data Years Available: 
Mode of Collection: 
Selected Content: 
NEI includes data for four criteria air pollutants (substances for which EPA has set health-based standards): carbon monoxide, nitrogen oxides, sulfur dioxide, and particulate matter. The NEI also includes emissions of two substances that enable and facilitate the formation of criteria air pollutants: volatile organic compounds, and ammonia.
Population Covered: 

EPA compiles the NEI database from these primary sources: Emissions inventories compiled by state and local environmental agencies; Databases related to EPA's Maximum Achievable Control Technology (MACT) programs to reduce emissions of hazardous air pollutants; Toxic Release Inventory (TRI) data for electric generating units; EPA's Emission Tracking System / Continuous Emissions Monitoring data (ETS/CEM) and Department of Energy fuel use data; For onroad sources, the Federal Highway Administration's estimate of vehicle miles traveled and emission factors from EPA's MOBILE computer model ; For nonroad sources, EPA's NONROAD computer model; Previous emissions inventories, if states do not submit current data.

Response Rates and Sample Size: 
Interpretation Issues: