Mr. Revesz and others said the change also defies the intent of the landmark Clean Air Act of 1970.
“These economic cost-benefit analyses have been an important driver of Clean Air Act regulations for 40 years,” said Richard Morgenstern, a former E.P.A. official who served from the Reagan to the Clinton administrations. “What this rule is doing is altering the math in such a way to potentially downplay the economic benefit to public health, so they are justified in writing weaker rules in the future.”
Allies of Mr. Trump applauded that prospect.
“This helps the Trump agenda because it limits E.P.A.’s freedom to push out new regulations,” said Steven J. Milloy, a member of Mr. Trump’s E.P.A. transition team and author of the book “Scare Pollution: Why and How to Fix the E.P.A.”
The fossil fuel industry expressed support for the move. “Through administrator Wheeler’s proposal, E.P.A. must now be consistent and transparent with the data and analysis used to justify decisions in its rule-making efforts,” said Anne Bradbury, chief executive of the American Exploration and Production Council, which represents oil and gas companies. “These reforms help to avoid federal rules that could otherwise hurt American workers, businesses and our economy.”
The future of Thursday’s actions will depend on the outcome of this November’s election. If former Vice President Joseph R. Biden Jr. defeats Mr. Trump and is inaugurated before the draft rule is made final, a process that can easily take up to a year, his administration could simply discard the E.P.A. proposal. If the rule is made final, but Mr. Biden wins the White House and Democrats take control of the Senate, they could use the Congressional Review Act to quickly undo the Trump-era regulation.
The act, almost never used until Mr. Trump took office, allows Congress to nullify any regulation that has been in place for fewer than 60 legislative days.
Thursday’s executive order would be even more vulnerable, since it could be undone with a new president’s signature.
Citing more than 41 million people out of work because of Covid-19, Mr. Trump said “Without intervention, the United States faces the likelihood of a potentially protracted economic recovery with persistent high unemployment.”