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Mercury and Air Toxics Standards (MATS)

Regulatory Actions

Final Mercury and Air Toxics Standards (MATS) for Power Plants

EPA Updates the Startup and Shutdown Provisions of the Mercury and Air Toxics Standards for Power Plants
November 7, 2014 – The EPA completed its reconsideration of the startup and shutdown provisions applicable to coal- and oil-fired electric utilities under the Mercury and Air Toxics Standards (MATS). This final rule includes updated definitions and work practice standards. EPA is also adjusting certain monitoring and testing requirements related to periods of startup and shutdown.

EPA Issues Direct Final Rule on e-Reporting and the Mercury and Air Toxics Standards for Power Plants
November 7, 2014 – The EPA issued a direct final rule and a parallel proposed rule to allow sources to comply with the MATS reporting requirements while we revise the Emissions Collection Monitoring Plan System (ECMPS) to accept all reporting that is required in the MATS rule. The rule is the first of two rulemakings that are designed to provide a single place for industry to submit their reports and data electronically. This action allows industry to submit data in PDF form for an interim time period. The EPA is publishing these reporting requirements as a direct final rule because the changes are noncontroversial and no adverse comments are anticipated. If adverse comments are received, the EPA will withdraw the direct final rule and address the comments when issuing a final rule based on the parallel proposal that is being issued in conjunction with the direct final rule.

EPA Reopens Public Comment Period on Reconsideration of Startup and Shutdown Provisions
June 25, 2013 – EPA is reopening, for 60 days, the public comment period on the startup and shutdown provisions included in the November 2012 proposed updates to pollution limits for new power plants under Mercury and Air Toxics Standards. Interested groups will have the opportunity to review new information provided during the original public comment period and subsequent EPA analysis of that information.

EPA Updates the Mercury and Air Toxics Standards for New Power Plants
March 28, 2013 - The Environmental Protection Agency (EPA) updated emission limits for new power plants under the Mercury and Air Toxics Standards (MATS). The updates only apply to future power plants; do not change the types of state-of-the-art pollution controls that they are expected to install; and will not significantly change costs or public health benefits of the rule.

EPA extends public comment period on proposed MATS reconsideration; no public hearing requested
December 12, 2012 - EPA has extended the comment period on the MATS reconsideration proposal by one week - until January 7, 2013. The Office of the Federal Register mistakenly published the MATS reconsideration proposal in the "final rules" section of the Nov. 30, 2012, Federal Register, and published a correction notice stating the inaccuracy on Dec. 5, 2012. Also, EPA did not receive any requests to hold a public hearing on this proposal, so no public hearing will be held.

EPA Proposes to Update the Mercury and Air Toxics Standards for New Power Plants
November 16, 2012 - The Environmental Protection Agency (EPA) proposed to update emission limits for new power plants under the Mercury and Air Toxics Standards (MATS). The updates would only apply to future power plants; would not change the types of state-of-the-art pollution controls that they are expected to install; and would not significantly change costs or public health benefits of the rule. The public will have the opportunity to comment for 30 days after publication in the Federal Register and at a public hearing in Washington DC if one is requested.

Mercury and Air Toxics Standards (MATS) Reconsideration
July 20, 2012 - EPA will review new technical information that is focused on toxic air pollution limits for new power plants under the Mercury and Air Toxics Standards. This reconsideration does not cover the standards set for existing power plants.

EPA announces Mercury and Air Toxics Standards (MATS) for power plants
December 21, 2011 - The U.S. Environmental Protection Agency (EPA) announced standards to limit mercury, acid gases and other toxic pollution from power plants.

Proposed Mercury and Air Toxics Standards (MATS) for Power Plants

EPA extends public comment period on proposed mercury and air toxics standards
June 21, 2011 - EPA is extending the timeline for public input by 30 days on the proposed mercury and air toxics standards for power plants. EPA will accept comment on the proposal until August 4, 2011.

EPA holds public hearings on proposed MATS rule
April 26, 2011 - EPA will hold three public hearings on the proposed mercury and air toxics standards signed on March 16, 2011. Each hearing will begin at 9:00 a.m. and continue until 8:00 p.m. (local time). The public may preregister to speak at the hearings at a specific time. People also may register in person on the day of the hearing, and will be worked in to openings in the schedule of speakers. To preregister to speak at the hearings, please contact Ms. Pamela Garrett, telephone 919-541-7966 or email garrett.pamela@epa.gov.

EPA proposes Mercury and Air Toxics Standards (MATS) for power plants
March 16, 2011 - The U.S. Environmental Protection Agency (EPA) is proposing standards to limit mercury, acid gases and other toxic pollution from power plants.

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History of this Regulation

Early 1990s

The Clean Air Act provides that EPA must take several steps before regulating air toxics emissions (such as mercury) from power plants. Deadlines for these steps were specified in a legal settlement of related litigation filed in the early 1990s.

October 1994

EPA enters settlement agreement providing that by November 15, 1995, it would complete its "Utility Air Toxics Study" to Congress; determine whether its is "appropriate and necessary" to regulate power plants under Clean Air Act section 112; and, if so, to issue such regulations by November 15, 2000. The parties subsequently agreed to extend the deadline for completing the Utility Air Toxics study until February 1998. EPA also agreed to solicit additional information from power plants and to use such information for making its appropriate and necessary determination.

December 1997

EPA analyzed mercury emissions from power plants and other industrial sources, the health and environmental impacts of those emissions and available control technologies. These findings were issued as a "Mercury Study Report to Congress" in December 1997.

You will need Adobe Acrobat Reader to view the Adobe PDF files on this page. See EPA's PDF page for more information about getting and using the free Acrobat Reader.

February 1998

In the "Utility Air Toxics Study" report to Congress, issued in February 1998, EPA focused on power plants, analyzing emissions of toxic air pollutants, including mercury.

November 1998

Deadline for EPA to determine whether it is "appropriate and necessary" to regulate power plant emissions under CAA section 112 is extended until December 15, 2000. EPA further agrees to issue proposed and final power plant mercury emission standards by December 15, 2003 and December 15, 2004, respectively.

December 2000

EPA announced its finding that it was "appropriate and necessary" to regulate coal- and oil-fired electric utilities under section 112 of the Clean Air Act. This finding, known as the Utility Air Toxics Determination (PDF) (7pp, 160K), triggered a requirement for EPA to propose regulations to control air toxics emissions, including mercury, from these facilities by December 15, 2003.

January 2004

On January 30, 2004, EPA proposed a rule with two basic approaches for controlling mercury from power plants. One approach would require power plants to meet emissions standards reflecting the application of the "maximum achievable control technology" (MACT) determined according to the procedure set forth in section 112(d) of the Clean Air Act. If implemented, this proposal would reduce nationwide mercury by 14 tons or about 30 percent by early 2008. A second approach proposed by EPA would create a market-based "cap and trade" program that, if implemented, would reduce nationwide utility emissions of mercury in two phases. When fully implemented mercury emissions would be reduced by 33 tons (nearly 70 percent). EPA proposed to pursue the cap and trade approach either under Section 111 or Section 112 of the Clean Air Act.

EPA also proposed to revise its December 2000 finding that it is "appropriate and necessary" to regulate utility hazardous air emissions using the MACT standards provisions (section 112) of the Clean Air Act.

March 2004

On March 16, 2004, EPA proposed a supplement to its January 2004 proposal. This action provided details on the proposed mercury trading program and methodologies for measuring mercury emissions.

April 2004

To afford the public with an additional opportunity to comment on EPA's proposal, EPA agreed to extend the deadline for issuance of the final power plant mercury rule from December 15, 2004 to March 15, 2005.

December 2004

On December 1, 2004, EPA issued a Notice of Data Availability (NODA) summarizing the modeling analyses presented by EPA and the commenters, and soliciting comment on the inputs and assumptions underlying those analyses. The NODA also sought comment on EPA’s benefits assessment. The public comment period closed January 3, 2005.

March 2005

On March 15, 2005, EPA issued the final Clean Air Mercury Rule.

The Clean Air Mercury Rule established “standards of performance” limiting mercury emissions from new and existing utilities and created a market-based cap-and-trade program to reduce nationwide utility emissions of mercury in two phases.

February 2008

On February 8, 2008, the D.C. Circuit vacated EPA's rule removing power plants from the Clean Air Act list of sources of hazardous air pollutants. At the same time, the Court vacated the Clean Air Mercury Rule. Read the Court's Opinion (PDF) (18pp, 51k)

EPA is developing air toxics emissions standards for power plants under the Clean Air Act (Section 112), consistent with the D.C. Circuit’s opinion (PDF) (18pp, 51k) regarding the Clean Air Mercury Rule (CAMR). EPA intends to propose air toxics standards for coal- and oil-fired electric generating units by March 16, 2011 and finalize a rule by November 16, 2011. Additional details

February 2009

On February 6, 2009, the Department of Justice, on behalf of EPA, asked the Supreme Court to dismiss EPA’s request (petition for certiorari) that the Court review the D.C. Circuit Court’s vacatur of the Clean Air Mercury Rule (CAMR). Read the Acting Solicitor General’s motion (PDF). (2pp, 13k)

On February 23, 2009, the Court also denied the Utility Air Regulatory Group’s request to review the U.S. Circuit Court of Appeals decision.

December 2009

On December 24, 2009, EPA approved an Information Collection Request (ICR) requiring all US power plants with coal-or oil-fired electric generating units to submit emissions information for use in developing air toxics emissions standards. Additional details

March 2011

On March 16, 2011, EPA proposed a rule that would reduce emissions from new and existing coal- and oil-fired power plants. This proposed rule would replace the court-vacated Clean Air Mercury Rule.

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