FACT SHEET

Mercury and Air Toxics Standards for Power Plants:
Proposed Reaffirmation of the Appropriate and Necessary Finding

•	On January 31, 2022, the Environmental Protection Agency (EPA) proposed to reaffirm that
it remains appropriate and necessary to regulate hazardous air pollutants (HAP), including
mercury, from power plants after considering cost.

o This action revokes a 2020 finding that it was not appropriate and necessary to
regulate coal- and oil-fired power plants under Clean Air Act (CAA) section 112,
which covers toxic air pollutants.

•	EPA reviewed the 2020 finding and considered updated information on both the public
health burden associated with HAP emissions from coal- and oil-fired power plants as well
as the costs associated with reducing those emissions under the Mercury and Air Toxics
Standards (MATS).

•	After weighing the public risks posed by these emissions to all Americans and to
particularly exposed and sensitive populations, against the costs of reducing this harmful
pollution, EPA proposes to conclude that it remains appropriate and necessary to regulate
these emissions.

•	Today's proposed action, if finalized, would ensure that coal- and oil-fired power plants
continue to control emissions of hazardous air pollution and that the agency properly
interprets the CAA to protect the public from hazardous air emissions.

o EPA is not proposing to change the status of coal- and oil-fired power plants as
affected source categories for regulation under section 112 of the CAA, so the
existing emissions standards for MATS would remain in effect and unchanged.

•	The review that led to this action was directed by President Biden's January 20, 2021,
Executive Order 13990, "Protecting Public Health and the Environment and Restoring
Science to Tackle the Climate Crisis."

o This Executive Order directed EPA to review and consider publishing a proposed
action to suspend, revise, or rescind the May 22, 2020, final action known as the
MATS Supplemental Finding and Residual Risk and Technology Review (RTR).

•	Executive Order 13990 also directed EPA to re-evaluate the MATS Risk and Technology
Review.

o EPA is soliciting information on the cost and performance of new or improved

technologies that control HAP emissions, improved methods of operation, and risk-
related information to further inform the Agency's re-evaluation of the MATS RTR.

o EPA will issue a separate action based on the Agency's assessment of the RTR.

•	Prior to MATS, power plants were the largest domestic source of mercury and other air
toxic pollutants such as hydrogen chloride and selenium. They were also among the largest
domestic contributors of arsenic, chromium, cobalt, nickel, hydrogen cyanide, beryllium,
and cadmium. These sources also emitted significant amounts of sulfur dioxide, nitrogen
oxides, and particulates.

•	EPA finalized MATS in 2012 and required sources to meet emissions reduction standards by
2016. The rule, along with significant changes in the power sector, has been extremely
effective in keeping hazardous air pollutants from power plants out of the air. Between

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2010 and 2017 mercury emissions from power plants within the U.S. were reduced by 86%,
non-mercury metal emissions were reduced by 81%, and acid gases emissions were reduced
by 96%.

•	Controlling HAP emissions from power plants improves public health for all Americans by
reducing fatal heart attacks, reducing cancer risks, avoiding neurodevelopmental delays in
children, and by helping to restore certain ecosystems people and businesses value. These
public health improvements are especially important for children and particularly
vulnerable segments of the population such as indigenous communities, low-income
communities, and people of color who regularly consume the fish they catch.

BACKGROUND

•	On April 12, 2012, EPA re-affirmed its 2000 finding that it is appropriate and necessary to
regulate coal- and oil-fired EGUs for HAP and promulgated National Emission Standards for
Hazardous Air Pollutants for that source category, commonly known as the Mercury and Air
Toxics Standards or MATS.

•	In 2015, the U.S. Supreme Court, in Michigan v. EPA, held that the Agency had erred by not
taking cost into consideration when making its determination that regulation of HAP
emissions from coal- and oil-fired EGUs under section 112 of the CAA is appropriate and
necessary.

•	On April 25, 2016, EPA issued a supplemental finding in response to the Michigan decision
and found that, after a consideration of costs, it remained appropriate and necessary to
regulate HAP emissions from coal- and oil-fired EGUs.

•	On May 22, 2020, EPA reversed that determination, finding that, after weighing the costs of
compliance against certain benefits of regulation, it is not appropriate and necessary to
regulate coal- and oil-fired EGUs under section 112 of the CAA.

•	The May 22, 2020, final action also included a RTR of MATS.

PUBLIC HEARING AND COMMENT

•	EPA will hold a virtual public hearing for this proposed action. Further details will be
announced at https://www.epa.gov/stationarv-sources-air~pollution/mercurv-and~air~
toxics-standards.

•	EPA will accept comment on the proposal for 60 days after publication in the Federal
Register.

•	Comments, identified by Docket ID No. EPA-HQ-OAR-2018-0794, may be submitted by one
of the following methods:

° Go to https://www.reeulations.gov/ and follow the online instructions for

submitting comments,
o Send comments by email to a-and-r~docket@epa.gov. Attention Docket ID No. EPA-
HQ-OAR-2018-0794 in the subject line of the message.

•	Out of an abundance of caution for members of the public and our staff, the EPA Docket
Center and Reading Room are closed to the public, with limited exceptions, to reduce the
risk of transmitting COVID-19. Our Docket Center staff will continue to provide remote
customer service via email, phone, and webform.

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o We encourage the public to submit comments via https://www.reeulations.gov/ or
email, as there may be a delay in processing mail and faxes. Hand deliveries and
couriers may be received by scheduled appointment only,
o For further information on EPA Docket Center services and their current status,
please visit us online at https://www.epa.eov/dockets.

FOR MORE INFORMATION

•	Interested parties can download a copy of the proposed rule from EPA's website at the
following address: https://www.epa.eov/stationarv-sources-air~pollution/mercurv-and~air~
toxics-standards.

•	Today's action and other background information are also available electronically at
https://www.reeulations.eov/. EPA's electronic public docket and comment system.

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