Toxic nerve agents from airoplane engines can 'bleed' into ventilation systems


Terry Williams, a veteran American Airlines flight attendant of 17 years, noticed a 'misty haze type of smoke' on Flight 843 as it taxied toward a gate in Dallas, Texas in 2007. Between a tickle in her throat, cough and headache, Williams thought she had the start of a common cold when she stepped off the flight in question. But she says the symptoms grew worse and included a nasal discharge she described as 'neon green, the same color as antifreeze'. Within several weeks, Williams says, she had to make repeated visits to emergency rooms before a neurologist told her she'd been the victim of toxic exposure.

Since the early 1960s, air in passenger jets has typically combined re-circulated existing cabin air with air bled off the engines. The air pulled into the engines is cooled and compressed before it is pumped into the the plane. It is this 'bleed air' (known as a 'fume event') that Terry Williams' claims was contaminated.

According to William Nazaroff, a professor of civil and environmental engineering at University of California, Berkeley, leaks in the seals that keep engine oil in place could cause chemically laden fumes to enter the air stream. A specific concern is tricresyl phosphate, a chemical compound used in nerve agents and pesticides to which high exposures have resulted in neurotoxic health consequences.

How often "fume events" happen, and how often they are reported, is disputed.

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First Published in July 2009

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