The Biden administration on Monday reinstated a way of measuring the benefits of reducing air pollution, the first step in a plan that could tighten limits on the amount of mercury that can be discharged from coal-burning power plants.

Mercury is a neurotoxin that poses a particular danger to the brain development of children and fetuses.

The mercury announcement is among several recent actions taken or planned by the Biden administration that are aimed at reducing pollution in air and water. After a first year in which President Biden tried to push ambitious climate legislation through Congress only to see it stall, the administration is using its regulatory machinery to try to curb pollution.

In many cases, the Biden administration is restoring environmental regulations that had been weakened by President Donald J. Trump before it lays the groundwork for even stronger rules to come.

For example, it has revived Obama-era limits on tailpipe emissions but said it intends to draft a more ambitious rule designed to speed up the conversion of the American automobile industry from gas powered cars to electric vehicles. It has also proposed new restrictions on methane, a powerful greenhouse gas, and plans tighter limits on industrial soot as well as pollutants in waterways and wetlands.

The E.P.A. has limited mercury emissions from coal plants since 2012. But during the Trump administration, the agency concluded that the rule’s cost to industry outweighed its benefits and therefore it was no longer “appropriate and necessary.” That finding allowed the Trump administration to stop enforcing the mercury limit, even though it remained on the books.

The Biden administration is now proposing to return to an Obama-era method of calculating the impact of regulation in a way that considers collateral benefits, such as reducing fine particulate matter and smog, when estimating the gains expected from lower mercury emissions.

Using that method would enable the E.P. A. to conclude that the costs of the rule to industry is offset by public health benefits such as prevention of disease and premature deaths. That would provide the legal justification to enforce the existing mercury regulations. The E.P.A. will open the proposal for a 60-day comment period, and is expected to finalize the policy later this year. The agency will also take public comments on whether it should tighten the existing mercury regulation even further.

“Sound science makes it clear that we need to limit mercury and toxins in the air to protect children and vulnerable communities from dangerous pollution,” said Michael Regan, the E.P.A. administrator. “E.P.A. is committed to aggressively reducing pollution from the power sector so that all people, regardless of ZIP code or amount of money in their pocket, can breathe clean air and live healthy and productive lives.”

E.P.A. officials had completed work to restore the mercury policy last fall, when they sent it to the White House for review. But administration officials put a hold on the policy, worried that it would antagonize industry and lawmakers just as President Biden was seeking support for his climate and social policy bill known as Build Back Better, according to two people familiar with the matter who spoke on the condition of anonymity.

After negotiations over Build Back Better collapsed in December, administration officials decided to move forward with the mercury policy while congressional Democrats try to salvage the legislation.

Environmental advocates praised the renewed enforcement of the mercury rule, which was the first federal standard to require power plants to install expensive “scrubber” technology to reduce emissions of the neurotoxin. At the time of the Trump administration rollback, many environmental law experts saw it as a first step toward eliminating other pollution limits.

“This was all an effort by the Trump administration to make the case for limiting future regulations, to make it harder to regulate the industry,” said Matthew Davis, a former E.P.A. official who helped to write the mercury rule and then left government in part because the Trump administration sought to weaken it. Mr. Davis now works for the League of Conservation Voters, an advocacy group.

When the Obama administration crafted the mercury rule, it estimated it would cost the industry $9.6 billion a year, making it the most expensive clean-air regulation in history. It also valued the direct public health benefits of reducing mercury at $6 million a year — less than the cost to industry.

But then it tallied the “co-benefits” of installing the scrubbers: a reduction in other pollutants, including sulfur dioxide and fine particulate soot, which are linked to heart, brain, lung and respiratory diseases. Those related benefits were estimated to be worth $80 billion over five years, including the prevention of 4,700 heart attacks, 130,000 asthma attacks and 11,000 premature deaths annually.

In its April 2020 decision, the Trump administration discounted the co-benefits.

Michael McKenna, who worked on environmental policy in the Trump White House, said the government appeared caught in a frustrating rhythm.

“The ‘new’ regime’s only frame of reference is to undo what the previous regime did,” Mr. McKenna wrote in an email. “So we end up in a pointless cycle. There is little doubt that when the Republicans next take the White House (2024? 2028?), they will undo whatever has been done.”

While some in the coal industry oppose the return to enforcing the mercury rule, many electric utilities that operate coal-burning power plants are expected to support it, as they had already invested years ago in the “scrubbers” to tamp down emissions.

A lawyer for the Edison Electric Institute, which represents investor-owned electric utilities, wrote in an email that the companies were already complying with the rule, also known as the mercury and air toxics, or MATS, rule.

“EEI’s member companies have fully implemented the MATS rule and will continue to operate those pollution control technologies,” wrote Alex Bond, deputy general counsel for the institute. “The repeal of the underlying legal basis for MATS introduced new uncertainty and risk for companies that still are recovering the costs for installing those control technologies, and we appreciate the U.S. Environmental Protection Agency’s efforts to review and reinstate the appropriate and necessary determination.”