Press Release

Twenty-One AGs Oppose EPA Proposal to Undermine Legal Foundation of Mercury and Air Toxic Standards (MATS)

The EPA’s proposal “is unlawful, lacks a reasoned basis, and threatens enormous public health harms.”

Proposal unlawfully eliminates the EPA’s thrice-confirmed “appropriate and necessary finding;” paves the way for repeal of emissions limits on mercury and other harmful air pollutants from power plants.

Washington, D.C. — Massachusetts Attorney General Maura Healey led a coalition of 21 attorneys general in filing comments yesterday strongly opposing the Environmental Protection Agency (EPA)’s proposal to reverse its long-held position that regulations on emissions of hazardous air pollutants from fossil-fuel fired power plants — commonly known as Mercury and Air Toxics Standards (MATS) — are appropriate and necessary under the Clean Air Act.

“Only the Trump Administration and the coal lobbyists running EPA would try to gut the rules that protect children and pregnant women from mercury and toxic air pollution,” said Massachusetts Attorney General Maura Healey. “This proposal blatantly violates federal law and the right of all Americans to breathe clean air.”

Mercury is a known neurotoxin that can cause brain damage, and is particularly dangerous to developing fetuses. For many years, uncontrolled mercury contamination from power plants has caused widespread damage to human health and the environment — including the poisoning of waterways and fisheries. The EPA issued a final rule in 2012 that required the power industry to reduce emissions of mercury and other hazardous air pollutants. The industry complied, successfully achieving targeted reductions and, in the process, reducing harmful particulates and other pollutants. As noted in the attorneys general comments, the rule has yielded “an eighty-six percent reduction in power-plant mercury emissions” as well as “massive reductions in hazardous air pollutant emissions.”

Now, after the fact, the administration is proposing to withdraw its multiple determinations that it is “appropriate and necessary” to regulate hazardous air pollution from power plants based on an assertion that the EPA should have ignored the co-benefits of reducing harmful particulates when calculating the rule’s costs and benefits. The EPA claims that it is not seeking to undercut the legal obligation of power plants to comply with the MATS rule, but its proposal would do exactly that.

The attorneys general are demanding that the EPA withdraw the proposal, calling its attempt to revisit prior findings that it is “appropriate and necessary” to restrict emissions of mercury and other hazardous air pollutants “an improper attempt by the EPA to evade clear statutory limitations on its authority.” The attorneys general also emphasize that the agency’s attempt to ignore human health co-benefits from the rule’s reduction of harmful particulates is arbitrary and capricious, particularly when the agency virtually dismisses, as unquantifiable, the proven human health and environmental benefits associated with reductions of mercury — one of the most toxic substances known to man.

“The Trump administration’s new interpretation of the Clean Air Act, which would negate the agency’s ability to require power plant operators to reduce mercury emissions — after they already have successfully installed control equipment — epitomizes the ugly face of this administration’s concept of ‘deregulation,’” said David J. Hayes, Executive Director of the State Energy & Environmental Impact Center. “While this EPA never fails to question industry’s costs of complying with environmental controls, its two-faced dismissal of the health and environmental benefits of protecting Americans from mercury and other pollutants represents a new low. State attorneys general will not let this assault on basic health and environmental protections stand.”

In addition to Massachusetts, the attorneys general of California, Connecticut, Delaware, Illinois, Iowa, Maine, Maryland, Michigan, Minnesota, Nevada, New Jersey, New Mexico, New York, North Carolina, Oregon, Rhode Island, Vermont, Virginia, Washington, and Washington, D.C. also joined in filing the comments.


In 2012, the EPA published the MATS rule to regulate emissions of mercury, acid gases and other toxic pollutants from power plants as “appropriate and necessary” under the Clean Air Act. In 2015, the Supreme Court ruled in Michigan v. EPA that the EPA must consider compliance costs when determining whether regulations on fossil fuel-fired power plants are “appropriate and necessary.” In 2016, the EPA responded with a Supplemental Finding confirming that the overall benefits of the MATS rule outweigh the costs of compliance.

At an EPA hearing in March 2019, a representative of Massachusetts Attorney General Maura Healey testified against the proposal. The testimony warned that such an approach “disregards the purpose of the Clean Air Act, fundamental economic principles, and the direction of the U.S. Supreme Court,” and emphasized that the existing MATS rule “has had no adverse impacts on ratepayers or electric system reliability.”


About the State Energy & Environmental Impact Center:
The State Energy & Environmental Impact Center at NYU School of Law is a nonpartisan academic center at NYU School of Law. The Center is dedicated to working towards a healthy and safe environment, guided by inclusive and equitable principles. The Center studies and supports the work of state attorneys general (AGs) in defending, enforcing, and promoting strong laws and policies in the areas of climate, environmental justice, environmental protection, and clean energy.