Four flight attendants from Alaska Airlines are suing Boeing claiming that a longtime toxic ventilation defect in the function of commercial airliners made them seriously ill and left them with permanent health problems.

The plaintiffs, Vanessa Woods, Faye Oskardottir, Darlene Ramirez and Karen Neben, were working on a Boeing 737 on January 12, 2013, flying from Boston to San Diego when the plane’s crew noticed a strange smell in the cabin. Toxic air sickened the four flight attendants, some of whom vomited and passed out. Another began mumbling incoherently on the PA system as she was calling for help. Passengers who were health professionals came to their aid as the pilot made an emergency landing in Chicago, where the attendants were rushed to a local hospital.

Three of them say they are still experiencing tremors, neurological and memory problems stemming from the incident, and can’t work. Their lawsuit (joined by Neben’s husband, Nathan) claims Boeing knows its airplane cabins (except those on the Dreamliner) can become filled with toxic air, is a threat to crew and passengers, but won’t do anything to solve the problem.

The toxic air is the result of pumping cabin oxygen through the plane’s engines, a “bleed air” process that, in the event of a leak, can result in contamination with jet oil and its toxic byproducts. Those byproducts include chemicals used in nerve gases and pesticides that had been banned for certain uses by the Environmental Protection Agency in 2001, the complaint states. It also points out it’s been known since 1955 that inhaling heated oil can damage the brain, liver, kidneys and cause death.

The plaintiffs claim this problem is “a previously hidden and ‘dirty little secret’ of the commercial airline industry.” The Association of Flight Attendants told NBC that thousands of people traveling on commercial aircraft may have been exposed to these toxic fumes over the years, and still have the poisonous chemicals in their systems without being aware of it.

Further, the plaintiffs say a fix is available that Boeing has not bothered to install, and that the manufacturer has been “put on notice more than 40 times” over the past 60 years “that its aircraft was unreasonably dangerous but failed to rectify the flawed design.”

Boeing has been sued over this matter in the past and settled. They claimed that “cabin air is safe to breathe” and “contaminant levels are generally low,” according to TODAY.

-Noel Brinkerhoff, Danny Biederman

To Learn More:

Flight Attendants Say Boeing Has 'Dirty Little Secret' (by Lisa Klein, Courthouse News Service)

Toxic Fumes in Airplanes? Flight Attendants Sue Amid Claims of Exposure (by Ian Sager, TODAY)

Boeing Sued Over 'Toxic' Plane Cabin Air (by Keith Laing, The Hill)