Emissions rise from the American Electric Power Co. coal-fired John E. Amos Power Plant in Winfield, W.Va., on July 18. (Luke Sharrett/Bloomberg News)

The Trump administration wants to change federal rulemaking in a way that could make it easier to allow the release of harmful substances into the atmosphere.

It’s making the case with mercury, a powerful neurotoxin that can damage the brains of infants and young children. In a proposal sent to the White House on Friday, the Environmental Protection Agency suggested recalculating the costs and benefits of a 2011 rule to limit mercury from coal plants, in part by questioning whether it was justified in the first place.

The shift is part of a broader effort to narrow what the government counts as benefits when crafting air rules. If adopted, the change would prevent the office from calculating positive health effects -- known as “co-benefits” -- that come from reducing pollutants other than those being targeted.

Under President Barack Obama, the EPA estimated that it would cost utilities $9.6 billion a year to comply with the new standards, while limiting mercury would translate into merely $6 million in public health benefits. But the EPA estimated at the time that the soot and nitrogen oxide reductions that would accompany cuts to mercury pollution would save between $37 billion to $90 billion in annual health costs and lost workdays by preventing as many as 11,000 premature deaths and 4,700 heart attacks.

But under President Trump, the EPA has published proposals to loosen carbon dioxide limits on power plants, arguing that it was inappropriate to count “co-benefits” such as having less soot in the air. And in a proposed rollback last month of a rule aimed at curbing leaks of hydrofluorocarbons, a potent greenhouse gas, the administration eliminated language in its analysis saying that children, elderly and the poor “are most vulnerable to climate-related health effects.”

In an interview Monday, acting Administrator Andrew Wheeler said the EPA is focused on producing analyses that capture the specific impact of a rule -- in this case, mercury -- rather than the accompanying benefits that stem from installing new pollution controls on equipment.

“I just think it’s a little fuzzy math when you say, ‘Reduce mercury and we have all these other benefits over here,’ as the shiny object," Wheeler said, adding that the agency could still consider other benefits but should categorize them separately.

If enacted, the new approach could reverberate far beyond this single rule. Previous administrations have repeatedly incorporated the benefits of cutting fine-particulate matter and smog-forming pollutants into their calculations when imposing limits on other emissions such as carbon dioxide. Reducing soot and contributors to smog often produce much bigger health benefits than curbs on greenhouse gas emissions linked to climate change, for example, because these traditional pollutants contribute to heart and lung disease.

John Walke, a clean-air lawyer at the advocacy group Natural Resources Defense Council, said in an email that Wheeler and Bill Wehrum, the head of the EPA’s air office, are seeking to exclude legitimate health benefits that stem from limiting toxins in the air.

"The fraudulent denial of real-world benefits from clean air and climate safeguards is the unholy grail of EPA haters and polluting industry lobbyists,” Walke said.

Details of the rule were first reported by the New York Times.

Jeff Holmstead, who was head of the EPA’s air and radiation office under President George W. Bush and now represents some energy firms, said the Mercury and Air Toxics Standards represented the “most egregious” example of the Obama administration relying on incidental benefits to argue that a regulation was cost effective. “Really, all they are doing is saying that EPA has to live within the statutory framework that Congress established,” Holmstead said.

Wheeler defended the administration’s approach to public health during an event at EPA headquarters Monday celebrating Children’s Health Day. “We are here to highlight the many ways the EPA is helping to protect children where they live, where they learn and where they play,” he said, standing in front of a school bus with a cleaner diesel engine funded in part through an agency grant.

When reporters questioned Wheeler about whether some of the administration’s recent proposals would harm children’s health, he responded that the EPA had not changed the nation’s overall air quality standards. “We have a criticism with the way the Obama administration tried to calculate their benefits," he said.

In a separate policy proposal last month, the EPA suggested reversing an Obama rule limiting the release of hydrofluorocarbons from large refrigerating and air-conditioning units. Documents posted in the Federal Register show that a section detailing how climate change would disproportionately hurt young people, seniors and the poor was cut from the proposed rule after undergoing a White House review.

“EPA is refusing to be transparent about the true costs of climate change, particularly to vulnerable populations like children," said Amit Narang, regulatory policy advocate at Public Citizen.

Coal-fired power plants are the single biggest emitter of mercury, which can cause brain damage in young children. Over time, these emissions also build up in fish, whose elevated levels of mercury are absorbed by people who eat them.

Congress gave the EPA the authority in the 1990s to regulate the toxic metals that are the byproduct of burning coal — a list that also includes arsenic, nickel and selenium — but it took the agency years to develop a standard.

In 2015, the Supreme Court dealt a major blow to the Obama administration’s efforts, saying U.S. officials failed to properly consider economic costs. The court, in a 5-to-4 decision, remanded the rule back to the U.S. Court of Appeals for the D.C. Circuit with instructions that it should be sent back to the EPA in light of this cost-benefit analysis. In response, the EPA in April 2016 issued a final analysis detailing how the rule’s benefits outweighed its costs. That finding became the subject of litigation.

Last spring, the EPA asked a federal court to delay a case challenging the rule brought by 15 states and several companies. Wheeler said the new rule aims to address the Supreme Court’s critique of the previous administration’s approach.

The nation’s largest utility trade association, Edison Electric Institute, urged the EPA in July to leave the mercury rule “in place and effective” because the industry had already installed the required pollution controls. EEI estimates that the industry has spent $18 billion over the past five years, an average of $3.6 billion a year, installing scrubbers to capture toxic chemicals that otherwise would have been released into the air.

Industry groups such as the National Mining Association said the rule has already caused the closure of dozens of coal-fired power plants across the country.