At American Airlines, the problem grew acute enough last year that flight attendants reported worker illnesses from such fumes to the airline—and were punished by their employer for doing so. That’s according to the U.S. Department of Labor’s Occupational Safety and Health Administration (OSHA). 

American Airlines “retaliated against flight attendants who reported worker illnesses caused by toxic fumes entering aircraft cabin,” OSHA said Wednesday.

The agency initiated a whistleblower investigation on Aug. 2, 2022, after “flight attendants alleged the airline docked attendance points and discouraged them from reporting work-related injuries and illnesses,” it said.

“Our investigation found that the flight attendants engaged in protected activities when they reported illnesses related to jet fuel fumes seeping into the aircraft cabin,” said OSHA Area Director Timothy Minor in Fort Worth, Texas, where the airline is based, in the statement. “Workers must feel empowered to inform managers and others about potential hazards that jeopardize workers’ safety and health.”   

OSHA whistleblower statutes specifically protect airline workers from retaliation if they report violations of Federal Aviation Administration regulations. For this violation, OSHA’s proposed fine against American Airlines is a mere $6,837, but it serves as a warning and generates bad publicity. ​

A ‘chilling effect’ on whistleblowers

“When employers punish employees for doing so, they create a chilling effect that may stop workers from reporting future issues, putting their health and well-being, and that of coworkers, at risk,” Minor warned.

An American Airlines spokesperson wrote to Fortune: “The safety of our team members and customers is always American’s top priority. We respectfully disagree with the investigator’s findings and have scheduled a conference with OSHA to further discuss the investigation.” 

Fortune also reached out to OSHA for comments but received no immediate replies.

In 2017, American Airlines flight attendants complained about headaches after an Airbus A330 landed in Orlando. The same aircraft had experienced at least three fumes-related incidents in the previous three months, ABC News reported at the time.

But it isn’t just American Airlines.

A plane’s engines suck in outside air, some of which gets sent into the air-conditioning systems. If there’s a broken seal or some other mechanical problem, toxic gases can leak into the air breathed by crew and passengers.

“This is the tobacco and asbestos of aviation,” said pilot Eric Tellmann at a 2016 meeting of American Airlines pilots, according to the Los Angeles Times. He recounted nearly passing out from fumes while serving as a copilot with Spirit Airlines the previous year.