The Trump administration in May began the process of replacing the small army of outside science advisers at the Environmental Protection Agency. In June, 38 additional EPA advisers were notified that their appointments would not be renewed in August. To Mr. Trump’s critics, this is another manifestation of his administration’s “war on science.” Histrionics aside, the administration’s actions are long overdue.

The most prominent of the EPA’s myriad boards of outside advisers are the Science Advisory Board and the Clean Air...