The Air Emissions Trends site provides national trends of criteria pollutant and precursor emissions data based on the the National Emissions Inventory (NEI) from 1970 - the latest NEI year.

Air Trends provides geographic trend information for specific air pollutants.

Air Trends provides geographic trend information for specific air pollutants.

A web page that describes and links to EPA systems for accessing and downloading ambient (outdoor) air quality and emissions data

A web page that describes and links to EPA systems for accessing and downloading ambient (outdoor) air quality and emissions data

This web service contains layers that depict annual emissions for 2014 at the facility and county level for the following criterial pollutants: CO, Lead, NH3, NOx, PM10, PM25, SO2, and VOC. The National Emissions Inventory (NEI) is a comprehensive and detailed estimate of air emissions of criteria pollutants, criteria precursors, and hazardous air pollutants from air emissions sources. The NEI is released every three years based primarily upon data provided by State, Local, and Tribal air agencies for sources in their jurisdictions and supplemented by data developed by the US EPA. The NEI is built using the Emissions Inventory System (EIS) first to collect the data from State, Local, and Tribal air agencies and then to blend that data with other data sources. NEI point sources include emissions estimates for larger sources that are located at a fixed, stationary location. Point sources in the NEI include large industrial facilities and electric power plants, airports, and smaller industrial, non-industrial and commercial facilities. A small number of portable sources such as some asphalt or rock crushing operations are also included. Some states voluntarily also provide facilities such as dry cleaners, gas stations, and livestock facilities, which are otherwise included in the NEI as nonpoint sources. The emissions potential of each facility determines whether that facility should be reported as a point source, according to emissions thresholds set in the Air Emissions Reporting Rule (AERR). NEI Point Sources are all included in the EIS Point Data Category. NEI nonpoint sources include emissions estimates for sources which individually are too small in magnitude to report as point sources. These emissions sources are included in the NEI as a county total or tribal total (for participating tribes). Examples include residential heating, commercial combustion, asphalt paving, and commercial and consumer solvent use. NEI nonpoint sources are all included in the EIS Nonpoint Data Category.

This web service contains layers that depict annual emissions for 2014 at the facility and county level for the following criterial pollutants: CO, Lead, NH3, NOx, PM10, PM25, SO2, and VOC. The National Emissions Inventory (NEI) is a comprehensive and detailed estimate of air emissions of criteria pollutants, criteria precursors, and hazardous air pollutants from air emissions sources. The NEI is released every three years based primarily upon data provided by State, Local, and Tribal air agencies for sources in their jurisdictions and supplemented by data developed by the US EPA. The NEI is built using the Emissions Inventory System (EIS) first to collect the data from State, Local, and Tribal air agencies and then to blend that data with other data sources. NEI point sources include emissions estimates for larger sources that are located at a fixed, stationary location. Point sources in the NEI include large industrial facilities and electric power plants, airports, and smaller industrial, non-industrial and commercial facilities. A small number of portable sources such as some asphalt or rock crushing operations are also included. Some states voluntarily also provide facilities such as dry cleaners, gas stations, and livestock facilities, which are otherwise included in the NEI as nonpoint sources. The emissions potential of each facility determines whether that facility should be reported as a point source, according to emissions thresholds set in the Air Emissions Reporting Rule (AERR). NEI Point Sources are all included in the EIS Point Data Category. NEI nonpoint sources include emissions estimates for sources which individually are too small in magnitude to report as point sources. These emissions sources are included in the NEI as a county total or tribal total (for participating tribes). Examples include residential heating, commercial combustion, asphalt paving, and commercial and consumer solvent use. NEI nonpoint sources are all included in the EIS Nonpoint Data Category.

This US EPA Office of Air and Radiation, Office of Air Quality Planning and Standards, Air Quality Assessment Division, Air Quality Analysis Group (OAR, OAQPS, AQAD, AQAG) web service contains the following layers created from the 2008, 2011 and 2014 National Emissions Inventory (NEI): All Pollutants, which include hazardous air pollutants (HAPs) and criteria air pollutants (CAPs) Criteria Majors, which include CAP point source emissions ≥ 100 tons per year (except Lead which is ≥ 0.5 tons per year) Criteria Minors, which include CAP point source emissions < 100 tons per year (except Lead which is < 0.5 tons per year). Layers are drawn at all scales. The National Emission Inventory (NEI) is a comprehensive and detailed estimate of air emissions of criteria pollutants, criteria precursors, and hazardous air pollutants from air emissions sources. The NEI is released every three years based primarily upon data provided by State, Local, and Tribal air agencies for sources in their jurisdictions and supplemented by data developed by the US EPA. The NEI is built using the Emissions Inventory System (EIS) first to collect the data from State, Local, and Tribal air agencies and then to blend that data with other data sources. NEI point sources include emissions estimates for larger sources that are located at a fixed, stationary location. Point sources in the NEI include large industrial facilities and electric power plants, airports, and smaller industrial, non-industrial and commercial facilities. A small number of portable sources such as some asphalt or rock crushing operations are also included. Some states voluntarily also provide facilities such as dry cleaners, gas stations, and livestock facilities, which are otherwise included in the NEI as nonpoint sources. The emissions potential of each facility determines whether that facility should be reported as a point source, according to emissions thresholds set in the Air Emissions Reporting Rule (AERR). NEI Point Sources are all included in the EIS Point Data Category. NEI nonpoint sources include emissions estimates for sources which individually are too small in magnitude to report as point sources. These emissions sources are included in the NEI as a county total or tribal total (for participating tribes). Examples include residential heating, commercial combustion, asphalt paving, and commercial and consumer solvent use. NEI nonpoint sources are all included in the EIS Nonpoint Data Category.

This US EPA Office of Air and Radiation, Office of Air Quality Planning and Standards, Air Quality Assessment Division, Air Quality Analysis Group (OAR, OAQPS, AQAD, AQAG) web service contains the following layers created from the 2008, 2011 and 2014 National Emissions Inventory (NEI): All Pollutants, which include hazardous air pollutants (HAPs) and criteria air pollutants (CAPs) Criteria Majors, which include CAP point source emissions ≥ 100 tons per year (except Lead which is ≥ 0.5 tons per year) Criteria Minors, which include CAP point source emissions < 100 tons per year (except Lead which is < 0.5 tons per year). Layers are drawn at all scales. The National Emission Inventory (NEI) is a comprehensive and detailed estimate of air emissions of criteria pollutants, criteria precursors, and hazardous air pollutants from air emissions sources. The NEI is released every three years based primarily upon data provided by State, Local, and Tribal air agencies for sources in their jurisdictions and supplemented by data developed by the US EPA. The NEI is built using the Emissions Inventory System (EIS) first to collect the data from State, Local, and Tribal air agencies and then to blend that data with other data sources. NEI point sources include emissions estimates for larger sources that are located at a fixed, stationary location. Point sources in the NEI include large industrial facilities and electric power plants, airports, and smaller industrial, non-industrial and commercial facilities. A small number of portable sources such as some asphalt or rock crushing operations are also included. Some states voluntarily also provide facilities such as dry cleaners, gas stations, and livestock facilities, which are otherwise included in the NEI as nonpoint sources. The emissions potential of each facility determines whether that facility should be reported as a point source, according to emissions thresholds set in the Air Emissions Reporting Rule (AERR). NEI Point Sources are all included in the EIS Point Data Category. NEI nonpoint sources include emissions estimates for sources which individually are too small in magnitude to report as point sources. These emissions sources are included in the NEI as a county total or tribal total (for participating tribes). Examples include residential heating, commercial combustion, asphalt paving, and commercial and consumer solvent use. NEI nonpoint sources are all included in the EIS Nonpoint Data Category.

This US EPA Office of Air and Radiation, Office of Air Quality Planning and Standards, Air Quality Assessment Division, Air Quality Analysis Group (OAR, OAQPS, AQAD, AQAG) web service contains the following layers created from the 2008, 2011 and 2014 National Emissions Inventory (NEI): Carbon Monoxide (CO), Lead, Ammonia (NH3), Nitrogen Oxides (NOx), Particulate Matter 10 (PM10), Particulate Matter 2.5 (PM2.5), Sulfur Dioxide (SO2), Volatile Organic Compounds (VOC). Each of these layers conatin county level emissions for 2008, 2011, and 2014. Layers are drawn at all scales. The National Emission Inventory (NEI) is a comprehensive and detailed estimate of air emissions of criteria pollutants, criteria precursors, and hazardous air pollutants from air emissions sources. The NEI is released every three years based primarily upon data provided by State, Local, and Tribal air agencies for sources in their jurisdictions and supplemented by data developed by the US EPA. The NEI is built using the Emissions Inventory System (EIS) first to collect the data from State, Local, and Tribal air agencies and then to blend that data with other data sources. NEI point sources include emissions estimates for larger sources that are located at a fixed, stationary location. Point sources in the NEI include large industrial facilities and electric power plants, airports, and smaller industrial, non-industrial and commercial facilities. A small number of portable sources such as some asphalt or rock crushing operations are also included. Some states voluntarily also provide facilities such as dry cleaners, gas stations, and livestock facilities, which are otherwise included in the NEI as nonpoint sources. The emissions potential of each facility determines whether that facility should be reported as a point source, according to emissions thresholds set in the Air Emissions Reporting Rule (AERR). NEI Point Sources are all included in the EIS Point Data Category. NEI nonpoint sources include emissions estimates for sources which individually are too small in magnitude to report as point sources. These emissions sources are included in the NEI as a county total or tribal total (for participating tribes). Examples include residential heating, commercial combustion, asphalt paving, and commercial and consumer solvent use. NEI nonpoint sources are all included in the EIS Nonpoint Data Category.