Emissions Inventories

The Air Emissions Inventory & Attainment Planning Branch of the Air Division develops and manages air emission inventories for air quality planning, analysis and permitting. An air emission inventory represents the type and amount of air pollutants that are released from different sources. Several different types of inventories are maintained for these purposes.

Emissions Reporting- Air Emissions Reporting Requirements (AERR)

MDEQ is required by EPA to report actual air emissions for Title V facilities on a periodic basis. All Title V facilities are required to report every 3 years (i.e., emissions for calendar years 2023, 2026, etc.). In addition some larger Title V facilities (“Type A” sources) are required to report every year. The potential emissions thresholds used to determine if reporting is required annually or triennially is found in Appendix A to 40 CFR Part 51, Subpart A. A request for the actual emissions inventory is mailed out by DEQ in April of the year following the reporting year (i.e. April 2024 for reporting year 2023). For more information about the AERR, contact the emission inventory group.

EPA’s Combined Air Emissions Reporting System (CAERS)

For reporting year 2023, MDEQ will pilot the use of CAERS.  Information on CAERS is available here.  Questions regarding CAERS should be sent to CAERS@mdeq.ms.gov.

Point Source Inventories

Emissions from major commercial and industrial sources, also referred to as point sources, are quantified when facilities are permitted. The Air Division maintains an inventory of these emissions and can provide this information for Prevention of Significant Deterioration (PSD) modeling and other air quality analysis purposes. If a project requires modeling, please also contact the Environmental Permits Division to ensure the modeling follows the proper protocols.

To request inventory information for PSD modeling, please contact a member of the Emissions Inventory Group.

The following information will be needed:

  • Site latitude/longitude coordinates
  • Site address
  • Radius of inventory
  • Pollutants that are needed
  • When the inventory is needed
  • Your name and email
Mobile and Area Source Inventories

The Air Division reviews the emissions inventory generated by EPA for cars, trucks, boats, construction equipment and other non-stationary equipment, referred to as mobile sources, and minor commercial facilities and residences, referred to as area or nonpoint sources. While these sources of emissions may not be directly regulated by the Department of Environmental Quality, they can have a significant impact on air quality.


Air Pollutant Emissions Trends – EPA emissions summaries and reports for the entire United States

Air Emission Sources website – EPA air emissions website with general summaries

National Emissions Inventory – EPA Air emissions website with detailed reports

Office of Transportation and Air Quality – EPA information on mobile emissions sources