Minor Source Air Emission Inventories for Central Iowa due May 15

Published 1/17/2023 9:28:12 AM

Minor source facilities located in the central third of Iowa (counties listed below) and all portable plants must submit their Minor Source Emission Inventory (MSEI) for calendar year 2022 emissions by May 15, 2023. If your facility is required to complete this year’s report, you will receive a letter from DNR.

A complete air pollutant inventory is required by 567 Iowa Administrative Code (IAC) sub rule 21.1(3). DNR uses the data collected from an emissions inventory to identify emission levels and trends throughout the state, track Iowa's progress towards meeting national air quality standards, and develop control and maintenance strategies required by the federal Clean Air Act.

Starting January 1, 2023, the MSEI is required to be submitted using the State and Local Emissions Inventory System (SLEIS). The only exception is for group 2 grain elevators, concrete batch plants, crushing plants, and hot mix asphalt plants that use specialized forms or standardized online spreadsheets for emissions reporting. These forms and spreadsheets may continue to be used. The DNR offers several resources to assist facilities with emission inventories:

  • SLEIS - Online emissions reporting tool:
  • SLEIS training dates and links to register: eAirServices
  • Instructions, forms, and example calculations: gov/minorsourceforms
  • Emissions estimate tools (including spreadsheets for many processes): gov/eetools
  • Exemptions, FAQs, and tips to complete the inventory: gov/minorsources
  • Facilities with less than 100 employees may also contact the Iowa Air Emissions Assistance Program (IAEAP) at the University of Northern Iowa for free training and assistance. For more information, please visit

For questions related to the emissions inventory, please contact:

Below is a list of Central Iowa counties included in the 2022 Minor Source Emissions Inventory:

In north-central Iowa, DNR Field Office 2 region: Butler, Cerro Gordo, Floyd, Franklin, Grundy, Hamilton, Hancock, Hardin, Humboldt, Kossuth, Mitchell, Webster, Winnebago, Worth, and Wright.

In south-central Iowa, DNR Field Office 5 region: Appanoose, Boone, Clarke, Dallas, Decatur, Jasper, Lucas, Madison, Mahaska, Marion, Marshall, Monroe, Polk, Poweshiek, Story, Tama, Warren, and Wayne.

Finally, please note that as of January 1, 2023, only air construction and Title V operating permit applications submitted electronically in Iowa EASY Air will be accepted. Visit eAirServices for more information.