An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

Air Emissions Modeling

2007/2008 Version 5 Air Emissions Modeling Platforms

The 2007 emissions modeling platform was based on the 2008 National Emissions Inventory (NEI), version 2, with 2007 data substituted for EGUs and mobile sources.  The year 2007 was the base year for this platform because it was deemed a more appropriate year to model for particulate matter than 2008.  This was important because the primary use of this platform was for the Regulatory Impact Assessment for the 2012 Final National Ambient Air Quality Standards (NAAQS) for particulate matter less than 2.5 microns (PM2.5), also known as the “PM NAAQS”.

The 2007v5.0 emissions modeling platform includes information needed to support the development of emissions inputs for air quality modeling, including the inventories, ancillary data, and scripts required to process the emissions.  Data and scripts for the projected future year of 2020 are included with this platform.  For 2008, “Flat files” of the 2008 NEI version 3 annual emissions, plus associated stack parameters, are available with this platform. Note that the 2008 annual data are not suitable for modeling onroad mobile source or nonroad mobile source emissions because the temporal resolution is not sufficient.