WASHINGTON >> The Environmental Protection Agency plans to publish a new regulation today that would restrict the kinds of scientific studies the agency can use when it develops policies, a move critics say will permanently weaken the agency’s ability to protect public health.

Under the measure, the EPA will require that the underlying data for all scientific studies used by the agency to formulate air and water regulations be publicly available. That would sharply limit the number of studies available for consideration because much research relies on confidential health data from study subjects.

Scott Pruitt, the EPA administrator, plans to announce the proposed regulation this afternoon at agency headquarters, according to three people who are familiar with the plans but not authorized to discuss them publicly.

Supporters and critics alike say the policy will have far-reaching consequences that could limit the EPA’s ability to regulate carbon emissions, air pollution and pesticides.

The new regulation means that some of the most important research of the past decades — for example, studies linking air pollution to premature deaths and measuring human exposure to pesticides — would not be available to policymakers if scientists were unwilling to break the confidentiality agreements they struck with study subjects to collect sensitive personal information.

Enacting the policy as a regulation, as the EPA intends to do, will involve accepting comments from the public and going through a lengthy bureaucratic process. But, if finalized, the measure would be difficult for a future administration to unravel.

Public health and environmental groups have vowed to challenge the move in court.

Richard J. Lazarus, a professor of environmental law at Harvard, said Pruitt would be “walking into a judicial minefield” if he told the EPA to no longer consider certain studies during agency rule-making.

That, Lazarus said, would be considered an arbitrary and capricious decision under the Administrative Procedure Act, which governs agency rule-making, and would “subject any agency regulation issued based on such a defective record to ready judicial invalidation.”

Supporters of the plan, which include the chemical and fossil-fuel industries and prominent climate change denialists, say the regulation will ensure that future EPA policies are based on science that can be independently verified.

A partial copy of the regulation obtained by the New York Times says the measure is intended to “strengthen the transparency and validity of EPA regulatory science,” and emphasizes the financial burdens created by federal regulations in addition to academic rigor.

“When EPA develops regulations, including regulations for which the public is likely to bear the cost to comply, using public resources, EPA should require that the underlying scientific information is available to the public,” the summary of the regulation says.

The public will be given 30 days to offer comments on the proposal before a final rule is issued, according to the draft. The EPA did not respond immediately to a request for comment.

The announcement comes as Pruitt prepares to face Congress on Thursday to discuss multiple questions about his frequent first-class travel, large security detail and other use of taxpayer dollars. His supporters said they are encouraged that the ethics cloud hanging over him has not stopped Pruitt from pursuing ambitious new policies.

“This is the most important thing he can do,” said Steven J. Milloy, a longtime champion of the measure who worked on President Donald Trump’s EPA transition team and who runs a website aimed at undermining the established science of human-caused climate change. “This will really open up EPA science to public scrutiny.”

In an interview Sunday on WNYM-AM in New York, Pruitt said the measure would allow the public to test scientists’ findings for themselves.

“It gives people the opportunity in real time to peer review. It goes to the heart of what we should be about as an agency,” Pruitt said.