National Emissions Inventory (NEI)

The National Emissions Inventory (NEI) reports detailed, comprehensive estimates of air emissions for criteria pollutants, criteria precursors, and hazardous air pollutants every three years (e.g., 2011, 2014, 2017, and 2020). The majority of the data are submitted by State, Local, and Tribal air agencies using the EPA Emissions Inventory System. These data may also be supplemented by EPA-estimates using data from sources such as the Toxic Release Inventory and other programs. The key elements reported in NEI include sources, pollutants, geographic, temporal, and emissions components that represent emissions estimates from four primary source categories: Point (large sources located at a fixed, stationary location, e.g., industrial facilities and electric power plants); Nonpoint (sources too small to report as point sources, e.g., residential heating, commercial combustion); Onroad (on road gasoline, diesel, and other fueled vehicles); and Nonroad (off-road mobile sources that use gasoline, diesel, and other fuels, e.g., equipment for construction, lawn and garden, and aircraft ground support). Starting in 2020, wild land fire emission estimates are being aggregated to annual and county levels and included as nonpoint source data. An NEI Exploration tool is available to help users examine and retrieve data of interest.