Section 1 Introduction

The Environmental Protection Agency (EPA) has released the complete 2020 National Emissions Inventory (NEI). The 2020 NEI is available on the web at the “2020 NEI Data page”. This is the first, and final planned public release of the 2020 NEI. A partial 2020 NEI was released in January 2023 for the Point, Onroad Mobile, and Nonroad Mobile data categories. This March 2023 release includes the remaining Nonpoint data source category; other categories are the same as the January 2023 release.