EPA last week reversed a 2020 Trump administration decision that undermined the legal basis for the Mercury and Air Toxics Standards (MATS) for power plants, reaffirming that the rule is “appropriate and necessary.”

The agency’s final rule reaffirms the scientific, economic and legal underpinnings of MATS, which was designed to curb the release of harmful substances from coal- and oil-burning power plants.

EPA says there are about 519 electric generating units at 250 locations that are subject to MATS. “Because the EPA is not amending the MATS rule, there are no cost, environmental or economic impacts as a result of this action,” the agency said. “However, finalizing this affirmative threshold determination provides important certainty about the future of MATS for regulated industry, states, other stakeholders and the public.”

“Retaining these protections is a critical first step,” said Georges C. Benjamin, executive director of the American Public Health Association. “We now urge EPA to strengthen them. We need stronger standards to protect all communities from these pollutants, especially those living near power plants.”

MATS has been at the center of a long-running seesaw battle that has changed directions with legal rulings and with control of the White House.

Amendments to the Clean Air Act in 1990 gave EPA authority to regulate electric utility steam-generating, and the agency under the Clinton administration concluded in 2000 that regulations were “appropriate and necessary.” Under the George W. Bush administration, EPA reversed itself in 2005 and said the regulations were neither.

The Obama-era EPA reversed itself again and issued the final MATS rule in 2012; it said resulting improvements to public health alone would be worth $37 billion to $90 billion a year, given the impacts of mercury and toxics such as hydrogen chloride and selenium. Coal- and oil-burning plants were by far the largest domestic source of these contaminants, EPA said, and among the largest emitters of pollutants such as arsenic, chromium cobalt and nickel.

In Michigan v. EPA in 2015, the U.S. Supreme Court ruled that EPA must consider the cost of implementing regulations it was ordering. EPA in 2016 said it had done so, and reaffirmed that its regulations remained necessary and appropriate.

President Donald Trump famously declared an end to “the war on coal,” and in May 2020, EPA found it was no longer appropriate and necessary to regulate electric utility steam-generating units through MATS.

EPA also said the residual risk and technology review (RTR) mandated by Section 112 of the Clean Air Act showed that emissions had been reduced to the point that residual risk was at acceptable levels, and that there were no new advances in emissions controls that would provide further cost-effective reductions.

President Biden issued a flurry of executive orders on his first day in office in January 2021, among them No. 13990, which directed EPA to revisit the May 2020 action.

The decision EPA announced Friday revokes the 2020 decision and reaffirms the 2016 decision.

In its news release Friday, EPA hinted at political considerations, speaking of its 2020 actions as having been carried out by “the previous administration.” It said the 2020 action undercutting MATS “was based on a fundamentally flawed interpretation of the Clean Air Act that improperly ignored or undervalued vital health benefits from reducing hazardous air pollution from power plants.”

Mixed Reaction

Reaction was divided.

Edison Electric Institute President Tom Kuhn commended EPA, saying in a statement that his members had been successfully implementing MATS during the yearslong regulatory process.

“EEI’s member companies, and the electric power industry collectively, have invested more than $18 billion to install pollution-control technologies to meet these standards,” Kuhn said. “Since 2010, our industry has reduced its mercury emissions by more than 91%, and we have seen a significant change in our nation’s energy mix, which is getting cleaner and cleaner every day.”

U.S. Sen. Tom Carper (D-Del.), chair of the Senate Environment and Public Works Committee, cheered the move.

“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,” he said in a news release. “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.”

The committee’s ranking member, Sen. Shelley Moore Capito (R-W.Va.), said in a news release that EPA would now be even more opaque in its rulemaking process and more likely to overstep its legal authority.

“With today’s announcement, we are once again reminded that the Biden administration’s end goal is to shut down American coal plants, fire American coal workers and do everything in its power to make America less energy independent,” she said.

Earthjustice welcomed EPA’s announcement and called for the agency to go further. “Coal-fired and oil-fired power plants are among the worst of the worst polluters, and their toxic emissions fall hardest on communities of color and low-income communities,” Earthjustice attorney Jim Pew said in a news release.

In its announcement Friday, EPA highlighted the health impacts: “Controlling these emissions improves public health by reducing fatal heart attacks, reducing cancer risks, avoiding neurodevelopmental delays in children and helping protect our environment. These public health protections are especially important for anyone affected by hazardous air pollution, including children and particularly vulnerable segments of the population such as indigenous communities, low-income communities and people of color who live near power plants.”

It said that the requirements of MATS, and concurrent advances in the technology used by the power industry, had by 2017 resulted in emissions reductions of 96% in acid gases, 86% in mercury and 81% in other metals.