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 (85 FR 55744)
05/22/2020 - Final Supplemental Finding for MATS and Risk and Technology Review (85 FR 31286)
04/03/2020 - Proposed Electronic Reporting Revisions (85 FR 20342)
12/27/2018 - Proposed Revised Supplemental Finding for MATS and Risk and Technology Review (84 FR 2670)
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 (81 FR 52346)
- Denial Document for Reconsideration of Certain Startup and Shutdown Issues; MATS
04/14/2016 - Final Supplemental Finding about MATS and Costs (81 FR 24420)
03/17/2016 - Final Technical Corrections (81 FR 20172)
11/20/2015 - Proposed Supplemental Finding about MATS and Costs (80 FR 75025)
04/21/2015 - Denial of Petitions for Reconsideration of Certain Issues (80 FR 24218)
03/09/2015 - Interim Final Electronic Reporting Requirements (80 FR 15510)
12/19/2014 - Proposed Technical Corrections (80 FR 8442)
11/07/2014 - Final Updates to the Startup and Shutdown Provisions (79 FR 68777)
11/07/2014 - Direct Final Rule (79 FR 68795) with Parallel Proposal (79 FR 68840) on Electronic Reporting
03/28/2013 - Final Updates to the Standards for New Power Plants (78 FR 24073)
02/16/2012 - EPA Announces Final Mercury and Air Toxics Standards for Power Plants (77 FR 9304)
05/03/2011 - EPA Announces Proposed Mercury and Air Toxics Standards for Power Plants (76 FR 24976)
Additional Resources
Learn more about mercury, products that contain it, and actions to reduce it.