In an attempt to suppress peer-reviewed health science at the U.S. Environmental Protection Agency, Administrator Scott Pruitt signed a proposed rulemaking that drastically limits what science and data may be used to craft environmental protections. Any studies without public raw data—misleadingly dubbed “secret science” by Pruitt—are now off-limits. This includes many public health studies that rely on the confidential medical data of participants. Pruitt's new rule also conflicts with the standard practices of peer-reviewed scientific journals. While Pruitt and Republican lawmakers (who, it turns out, cooked up this policy in legislation that could not pass Congress) claim it promotes “transparency,” it actually invalidates a large swath of studies linking pollution to poor health and would lay the groundwork for industry-friendly rollbacks. Landmark research that helped form the bedrock of federal environmental protections—like that which links particulate matter from burning coal to premature deaths—is now at risk. Pruitt’s accusations of “secret science” are just another attempt to insert doubt where none exists and to sabotage efforts to protect Americans from pollution.