EPA Nods to Missouri's SO2 Emission Rule Refresh
Published Date: 6/27/2025
Proposed Rule
Summary
The EPA wants to approve Missouri’s updated plan to control sulfur dioxide pollution, swapping old rules for newer, clearer ones. This update affects power plants and cleans up outdated rules but won’t make pollution limits any easier or harder. No new costs or deadlines for businesses, just a smoother, smarter way to keep Missouri’s air clean.
Analyzed Economic Effects
4 provisions identified: 3 benefits, 1 costs, 0 mixed.
State swaps in Missouri SO2 rule
EPA is proposing to approve Missouri replacing the prior statewide sulfur dioxide (SO2) rule in the State Implementation Plan (SIP) with the newer rule 10 CSR 10-6.261. The change cleans up and clarifies the SIP across Missouri but the EPA says it does not change the stringency of limits or the State’s ability to meet the National Ambient Air Quality Standards (NAAQS).
Outdated SO2 requirements removed
The SIP revisions remove outdated SO2 requirements that applied to facilities that have closed, switched from coal to lower-sulfur fuels, or become subject to more stringent SO2 rules elsewhere in the Missouri SIP. This cleanup removes obsolete obligations from the SIP without changing overall pollution limits.
Reinstatement of SO2 limits at two plants
The SIP revisions reinstate SO2 emission limits for the Ameren-Labadie and Evergy-Hawthorn power plants that had previously been removed. EPA is proposing to approve those reinstated limits as part of the updated Missouri SIP.
Approval of sulfuric acid negative declaration
EPA is proposing to approve Missouri’s negative declaration for sources subject to sulfuric acid production requirements that the Missouri Department of Natural Resources submitted on May 4, 2022. That negative declaration states there are no sources in Missouri subject to those specific sulfuric acid production requirements.
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