WASHINGTON, D.C. — U.S. Senator Tom Carper (D-Del.), Chairman of the Senate Environment and Public Works (EPW) Committee, issued the following statement on the U.S. Environmental Protection Agency (EPA) reinstating the finding that it is “appropriate and necessary” to regulate mercury and toxic air pollution from power plants under the Mercury Air Toxics Standards (MATS). Under the MATS rule, power plants are now reducing mercury and other air toxic pollution by over 90 percent at about one-quarter of the costs originally estimated by EPA.

“Finally, we can put this issue to bed — EPA can and should regulate mercury and other harmful air pollution from power plants in our country,” said Senator Carper. “When the previous administration chose to remove the legal underpinnings of the MATS rule, they ignored the irrefutable science on the devastating impacts that mercury has on children’s health. Fortunately, EPA is now correcting course and bolstering the MATS rule. This decision will help ensure that our nation’s power plants continue to run on effective pollution control technology that protects communities’ health and economic wellbeing.”


From 1983 to 1993, Senator Carper served as Delaware’s only Member of Congress in the U.S. House of Representatives. There, he worked alongside the late John Dingell, then-chairman of the House Committee on Energy and Commerce, to pass the Clean Air Act Amendments of 1990. The 1990 law was a bipartisan piece of legislation that garnered support from 400 House Members and 89 Senators.

After the Clean Air Act Amendments of 1990 became law, Senator Carper worked with then-Senator Lamar Alexander (R-Tenn.) to develop legislation that would have required utilities to eventually reduce mercury emissions by 90 percent. When the Obama administration finalized the MATS rule in 2012, the rule required utilities to meet a 90 percent reduction in mercury emissions. MATS also required a 50 percent reduction in other air toxic emissions.

On January 31, 2022, Carper praised EPA’s proposed rule to reinstate the 2012 MATS rule.

During the Trump administration, as the senior-most Democrat on the EPW Committee, Carper fought tirelessly to defend the MATS rule:

  • May 20, 2020 – Carper released A Pandemic of Pollution staff report summarizing EPA’s actions to roll back clean air protections during the COVID-19 pandemic and highlighted the MATS rollback during an oversight hearing with then-EPA Administrator Andrew Wheeler.
  • April 16, 2020 – Carper slammed the administration’s final rule undermining MATS as the deadly COVID-19 pandemic was sweeping across the country.
  • November 12, 2019 – Carper and Alexander penned an op-ed in USA Today defending the MATS rule as a success, and urging EPA to not go forward with its rollback of the rule’s legal foundation.
  • March 18, 2019 – Carper testified at an EPA hearing to defend the MATS rule.
  • February 22, 2019 – Carper elevated the MATS issue as a priority in the nomination process of then-Acting Administrator Wheeler.
  • December 28, 2018 – Carper slammed the proposal after it was announced during a government shutdown, saying “EPA has decided to snatch defeat from the jaws of victory, and all Americans will suffer as a result.”
  • December 13, 2018 – Carper sent a letter to the Office of Information and Regulatory Affairs (OIRA) expressing grave concerns that in making this decision, EPA is ignoring or dismissing many of the MATS rule’s public health benefits and actual costs.
  • August 24, 2018 – Carper sent a letter with Alexander to EPA requesting that EPA keep the MATS rule in place.

Carper is also the long-time author of bipartisan legislation with Senator Susan Collins (R-Maine), the Comprehensive National Mercury Monitoring Act, to establish a national mercury monitoring network.