On June 17, 2025, US EPA published a proposed rule entitled, National Emission Standards for Hazardous Air Pollutants: Coal- and Oil-Fired Electric Utility Steam Generating Units, in the Federal Register. A copy of the proposed rule is available here.
The rule proposes to repeal certain amendments to the Mercury and Air Toxics Standards (MATS) Rule published on May 7, 2024. More specifically, EPA is proposing to repeal the amendments listed below.
- The filterable particulate matter (fPM) emission standard for existing coal-fired electric utility steam generating units (EGUs), which the EPA revised from 0.030 pounds per million British thermal units (lb/MMBtu) to 0.010 lb/MMBtu;
- The compliance demonstration requirement for the fPM emission standard for all coal- and oil-fired EGUs, which the EPA revised from allowing EGU owners and operators to choose between use of quarterly stack testing, use of continuous parametric monitoring systems (CPMS), or use of PM continuous emission monitoring systems (CEMS) to only allowing use of PM CEMS; and
- The Hg emission standard for existing lignite-fired EGUs, which the EPA revised from 4.0 pounds per trillion British thermal units (lb/TBtu) to 1.2 lb/TBtu.
In Section IV, Request for Comments, EPA is seeking responses to nine (9) questions related to the proposed action. Comments on this proposed rule must be received on or before August 11, 2025.
VIM Technologies will continue monitoring the progress of this proposed rule and provide updates as new developments occur. We encourage affected facilities, industry professionals, and interested parties to review the proposed changes in detail and submit comments to ensure that their perspectives are represented in the final decision-making process. If you have questions about compliance or how these potential changes may impact your operations, please contact our COMPAS team.
