This TSD describes how the emission inventories were prepared for air quality modeling by the U.S. Environmental Protection Agency (EPA) for criteria air pollutants to represent the years of 2016 and 2028. This document focuses on the emissions modeling data and techniques including the emission inventories, the ancillary data files, and the approaches used to transform inventories for use in air quality modeling. The starting point for the 2016 inventory was the 2014 National Emissions Inventory (NEI), version 2 (2014NEIv2), although many inventory sectors were updated to represent the year 2016 through the incorporation of 2016-specific state and local data along with nationally-applied adjustment methods. The year 2028 inventory was developed starting with the 2016 inventory using sector-specific methods as described below.You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.