“We are trying to give the E.P.A. the best science it can in order to make decisions,” said Dr. Michael Honeycutt, the new head of the E.P.A.’s scientific advisory board, who had a reputation at the Texas Commission on Environmental Quality for supporting policies that were more lax than those pushed by the federal government.

“We’re all scientists,” he said in an interview Tuesday. “I’ve never worked with a group of people more dedicated to trying to get the science right. We take this very seriously.”

Corry Schiermeyer, a spokeswoman for the E.P.A., said on Tuesday that the agency “always appreciates and respects the work and advice” of the scientific advisory board, while noting that Tuesday’s letters are drafts and could still be revised.

Some early critics of the Trump administration’s purge of the advisory-panel members said on Tuesday that their judgments may have been misplaced. Chris Zarba, who previously served as director of the E.P.A. science panel, credited the group for insisting on doing a comprehensive review of E.P.A. rules and said the work the group did points to the importance of the board remaining independent.

“It certainly looks like they were raising some very serious issues. I give them credit so far for stepping up and putting science first,” Mr. Zarba said.

Peter Wilcoxen, professor of public administration at Syracuse University, said he took the criticism as a hopeful sign. “The people on the board, regardless of what their affiliation was when they were appointed to it, took their role of trying to have the agency do the best science possible seriously. They weren’t on there just to try to politically steer the board one way or another,” he said.