Pollutant Emissions Summary Files for Earlier NEIs
Our official trends information is contained on the Air Pollutant Emissions Trends Data site. State and National trends data files and documentation are provided at this site for our CAP and CAP precursor air emission trends. We only condone and support use of trends at the state level and national levels from these specific files; we do not provide trends data at the county level. You are free to use older (pre-2020) NEI county-level data for a time-series analysis based on available older NEI data; however, these pre-2020 NEIs should be regarded as a “snapshot” of our best estimates at that time and no longer align with our latest trends data.
Our new trends approach uses a peer-reviewed analysis technique to minimize the methodology changes inherent to all older NEIs back through year 2002. Therefore, we do not support or suggest calculating county-level trends data from earlier NEIs. The latest trends data reflects the 2020 NEI released March 31, 2023, with estimates available through year 2022. In addition to the Tier 1 national and state trends, these new trends also provide data at the EIS sector level and black carbon and organic carbon for years 2002 through 2022. We only recommend use of these Air Pollutant Emissions Trends Data for the distinct purposes of understanding how air emissions have changed over time.
September 20, 2005: Summary files have been generated from the EPA's national emissions inventory (NEI) database for criteria air pollutants for the years 1990 and 1996 through 2001. The files are in ASCII text format and have been compressed. Each year includes data files and a readme file that explains the file structure.
January 20, 2016: Summary files have been added from 2002 and 2005 NEI for both criteria and hazardous air pollutants. The files are in both Excel and Access format and have been compressed.
For years prior to 1990 and for the years 1991 through 1995, the NEI database contains trend level data. This data is available in the annual air pollutant emissions trends report for 1970 through 2014.
Emissions Summary files: