Air Pollutant Emissions Trends Data
Current emission trends data (including “readme” files included in the spreadsheets) and the documentation of estimation methods are available via the links below. The latest version of the 1970 - 2024 data show the trends for Tier 1 categories which distinguish pollutant emission contributions among major source types. Improvements to the methods used to estimate emissions for the years 2002-2019 were introduced for the trends summaries released in 2023, and are retained for the current February 2025 update of these data. These updated procedures minimize the effects of method changes on emissions over this time frame. In addition, 2020 is represented by the 2020 NEI data, and 2021 and 2022 are based on the emissions modeling platform data with the 2020 NEI used where newer information for 2021 and 2022 was not available. Year 2023 data was updated for this release but is limited to information on electric generating units, mobile sources, and draft wildfires and agricultural field burning with 2022 estimates carried forward for all other data points. Year 2024 data is introduced in this updated trends release, but is limited to NOx and SO2 from electric generating units and projected emissions for onroad and nonroad sources, with 2023 estimates carried forward for all other data points.
First introduced in 2023, we again provide EIS sector specific national and state trends for the time frame 2002-2024, as well as the addition of black carbon and organic carbon as pollutants to all the files. The trends shown are for criteria air pollutants (CAPs) and precursors covered by the National Ambient Air Quality Standards (NAAQS), excluding lead. Lead emissions sharply declined after it was eliminated from gasoline and have remained low.
National Tier 1 CAPS Trends (xlsx) Criteria pollutants National Tier 1 for 1970 - 2024.
State Tier 1 CAPS Trends (xlsx) Criteria pollutants State Tier 1 for 1990 - 2024.
National and State EIS Sector CAPS Trends (xlsx) Criteria pollutants National State EIS Sector for 2002 - 2024.
National and State CAPS Trends by Tier 1 and EIS Sector (xlsx) National and State CAPS Trends by Tier 1 and EIS Sector for 2002 - 2024.
Trends Procedural Documentation - Any changes in the data or methodologies used to estimate the emissions for a specific time period will continue to be noted in future updates.
For more information on air trends visit the National Air Quality website.