Mercury and Air Toxics Standards
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Rule Summary
In the National Emission Standards for Hazardous Air Pollutants for Coal- and Oil-Fired Electric Utility Steam Generating Units (EGUs), also known as the Mercury and Air Toxics Standards or MATS, EPA set technology-based emissions standards for mercury and other hazardous air pollutants (HAP) emitted by units with a capacity of more than 25 megawatts. These standards reflect levels achieved by the best-performing sources and apply to existing and new EGUs.
MATS, along with significant changes in the power sector, has achieved significant health and environmental benefits by reducing a broad range of hazardous air pollutants. By 2017 mercury emissions had dropped by 86 percent - down to approximately 4 tons. Acid gas HAP and non-mercury metals are down 96 percent and 81 percent respectively when compared to 2010 levels.
Rule History
02/15/2023 - Final Revocation of the 2020 Reconsideration, and Affirmation of the Appropriate and Necessary Supplemental Finding
07/17/2020 - Final Electronic Reporting Provisions
05/22/2020 - Final Supplemental Finding for MATS and Risk and Technology Review
04/03/2020 - Proposed Electronic Reporting Revisions
12/27/2018 - Proposed Revised Supplemental Finding for MATS and Risk and Technology Review
08/08/2016 - Denials of Petitions for Reconsideration – Startup and Shutdown Provisions
- Notice of Final Action Denying Reconsideration on the MATS Startup and Shutdown Provisions
- Denial Document for Reconsideration of Certain Startup and Shutdown Issues; MATS
04/14/2016 - Final Supplemental Finding about MATS and Costs
03/17/2016 - Final Technical Corrections
11/20/2015 - Proposed Supplemental Finding about MATS and Costs
04/21/2015 - Denial of Petitions for Reconsideration of Certain Issues
03/09/2015 - Interim Final Electronic Reporting Requirements
12/19/2014 - Proposed Technical Corrections
11/07/2014 - Final Updates to the Startup and Shutdown Provisions
11/07/2014 - Direct Final Rule with Parallel Proposal on Electronic Reporting
03/28/2013 - Final Updates to the Standards for New Power Plants
11/16/2012 - Reconsideration of Certain Standards for New Power Plants and Requirements for Startup and Shutdown Periods
12/21/2011 - EPA Announces Mercury and Air Toxics Standards for Power Plants
Additional Resources
Learn more about mercury, products that contain it, and actions to reduce it.