1.3 Where can I obtain the 2023 NEI data?

The 2023 NEI data are available publicly in several different ways described below. Data are available to the reporting agencies and EPA staff via the Emission Inventory System (EIS).

1.3.1 Emission Inventory System Gateway

The EIS Gateway is available to all EPA staff, EIS data submitters (i.e., the S/L/T air agency staff), Regional Planning Organization staff that support state, local and tribal agencies, and contractors working for the EPA on emissions-related work. The EIS users can create reports to obtain raw input datasets for the 2023 NEI and to create summary files from these datasets as well as older versions of the NEI such as 2020, 2017, 2014, 2011, and 2008. The 2023 NEI dataset in the EIS is called “2023NEI”. For point sources, facility-, unit- or process-level reports provide the latest NEI emissions for the year selected, but the facility inventory will reflect the most current information submitted by S/L/Ts about the latest facility attributes (e.g., name, owner, and lists of units, processes, and release points). For example, if an Agency ID has been changed since the time EPA generated the 2023 NEI point source reports for the public website (April 15, 2026), then that new Agency ID will be in the Facility Inventory or a Facility Configuration report in the EIS but not in the public reports nor the Facility Emissions Summary reports run on the “2023NEI” dataset in the EIS.

1.3.2 NEI main webpage

Next, data from the EIS are exported for public release on the “2023 NEI webpage”. The 2023 NEI Data page includes the publicly-available version of the 2023 NEI. The 2023 NEI webpage includes the 2023 NEI plan and schedules, all publicly-available supporting materials by inventory data category (e.g., point, nonroad mobile, onroad mobile, and nonpoint), and this TSD.

Two types of point data summaries are available on the 2023 NEI Data page, facility summaries and process-level summaries. The source classification codes (SCC) data files section of the webpage provides the process level summaries for all data categories. These detailed CSV files (provided in zip files) contain emissions at the process level. Due to their size, they are broken out into EPA regions. Facility level by pollutant summaries are also available. These CSV files must be “linked” (as opposed to imported) to open them with Microsoft® Access®. County and tribe-level summaries for events are also provided.

With the final 2023 NEI release on May 29, 2026, the 2023 NEI Data page also includes a query tool that allows for summaries by EIS Sector or the more traditional Tier 1 summary level (for CAPs only) used in the “Air Pollutant Emissions Trends Data” reports. Summaries from the 2023 NEI Data site include national-, state-, and county-level emissions for CAPs, HAPs and GHGs. You can also choose which states, EIS Sectors, Tiers, and pollutants to include in custom-generated reports to download Comma Separated Value (CSV) files to import into Microsoft® Excel®, Access®, or other spreadsheet or database tools. Biogenic emissions and tribal data (but not tribal onroad mobile emissions) are also available from this tool. Tribal summaries are also posted under the “Additional Summary Data” section of this page.

Starting with the 2020 NEI, for the 2023 NEI, we have also developed an Online Data Retrieval to allow users to filter and download custom lists of facilities and county total emissions data for other data categories. This tool is also available on the “2023 NEI webpage”.

1.3.3 Modeling files

The modeling files, provided on the “Air Emissions Modeling website”, are provided in formats that can be read by the “Sparse Matrix Operator Kernel Emissions” (SMOKE). These files are also CSV formats that can be read by other systems, such as databases. The modeling files provide the process-level emissions apportioned to release points, and the release parameters for the release points. Release parameters include stack height, stack exit diameter, exit temperature, exit velocity and flow rate. The EPA may make changes to the NEI modeling files prior to use. The 2023 modeling platform has not yet been developed but will be based on the 2023 NEI once it is. Any changes between the NEI and modeling platform data would be described in an accompanying TSD for the 2023 Emissions Modeling Platform, which would also be posted at the above website.

The SMOKE flat files for the 2023 NEI are posted on the “2023 NEI Flat Files FTP site”.