WASHINGTON — The Environmental Protection Agency announced a new regulation Tuesday 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 E.P.A. 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 E.P.A. administrator, announced the proposed regulation this afternoon at agency headquarters, flanked by Republican lawmakers who sponsored legislation designed to achieve the same ends as the new regulation.

“The science that we use is going to be transparent, it’s going to be reproducible,” Mr. Pruitt said.