– The Trump administration on Thursday weakened regulations on the release of mercury and other toxic metals from oil and coal-fired power plants, another step toward rolling back health protections in the middle of a pandemic.

The new Environmental Protection Agency rule does not eliminate restrictions on the release of mercury, a heavy metal linked to brain damage. Instead, it creates a new method of calculating the costs and benefits of curbing mercury pollution that environmental lawyers said would fundamentally undermine the legal underpinnings of controls on mercury and many other pollutants.

By reducing the positive health effects of regulations on paper and raising their economic costs, the new method could be used to justify loosening restrictions on any pollutant that the fossil fuel industry has deemed too costly to control.

“That is the big unstated goal,” said David Konisky, a professor of public and environmental affairs at Indiana University. “This is less about mercury than about potentially constraining or handcuffing future efforts by the EPA to regulate air pollution.”

The change is the latest in the Trump administration’s long-running effort to roll back environmental regulations and reduce regulatory burdens, particularly on the coal, oil and gas industries.

Over the past few weeks as the nation struggled with the coronavirus, the administration has also rushed to loosen curbs on automobile tailpipe emissions, opted not to strengthen a regulation on industrial soot emissions and moved to drop the threat of punishment to companies that kill birds “incidentally.”

The deregulatory push appears designed to secure less restrictive rules quickly, in case Republicans lose control of Congress and the White House in November.

The mercury rollback is a particular victory for Robert E. Murray, the former chief executive of Murray Energy Corp. and a top fundraiser for Trump. Murray personally requested the rollback in a written “wish list” to top officials shortly after the president took office. The company has since declared bankruptcy and is undergoing a reorganization.

Environmental lawyers and public health leaders called the timing of the final mercury rule, as well as its substance, an attack on air quality.

“What is most disconcerting to me is this administration’s lack of interest in science and, frankly, their lack of concern for our nation’s children,” said Aaron Bernstein, interim director of the Center for Climate, Health and the Global Environment at the Harvard T.H. Chan School of Public Health. “Mercury pollution in the United States damages our children’s brains before they even come into the world, and estimates are that that cost is in the billions of dollars.”