Toxic cabin air may threaten passenger and crew health


Despite industry claims that toxins in contaminated cabin air are harmless, medical and scientific evidence is proving otherwise following the OPIN-related death of British Airways pilot Richard Westgate.

Nervous system damage due to “organophosphate-induced neurotoxicity,” or OPIN, has been identified as a major contributing factor to the death of the 43-year-old non-smoker and non-drinker. Because Westgate authorized medical testing before and after his death, a trio of researchers has been able to conduct post-mortem testing that reveals the link between Westgate’s illness and contaminated cabin air.

Professor M.B. Abou-Donia of Duke University Medical School, lead author of the study, said the air transport industry has failed to recognize three aspects of organophosphate exposure, including combined exposure to multiple compounds, the cumulative effects of repeated exposure, and individuals’ genetic predisposition to toxicity.

Despite known toxicity of compounds found in engine oil fumes since the 1930s, airlines’ safety literature omits any warning of health threats caused by breathing contaminated cabin air. The rationale for doing such has been that toxin levels are too low to cause harm. The organization trying to address these matters is Global Cabin Air Quality Executive. Their head of research Dr. Susan Michaelis said there is no basis for a “harmless level” of inhalation for these neurotoxins.

“Most of the substances in the oils and fluids do not have set limit values/exposure standards and therefore for the industry to say all levels found were safe and below government-established levels is incorrect,” said Michaelis.

A 2009 health care professional guide for treating those exposed to contaminated cabin air partially funded by the FAA states that exposure to organophosphate contaminated air sometimes causes airline workers to develop acute or chronic health effects. Additionally, the European Commission Directorate-General identified issues with cabin air as a possible national health concern at a December 2013 conference in Brussels.

Despite this limited regulatory recognition of the issue, the industry has contested need for action, resulting in many cases of unreported toxic air exposures for passengers and crew. A 2014 Australian Transport Safety Bureau report ­revealed passengers and crew flying nationally were exposed to toxic fumes more than 1000 times over the past five years, even including emergency landings especially because of fumes.

All aircraft, excepting the “bleed-free” frame of the Boeing 787, are susceptible to contaminated air, as cooled air from off the engines can “bleed” into the cabin. When engine oil seals leak or fail, oil fumes contaminate the “bleed air”, which goes directly to the flight deck air supply systems. That air is used to heat cabin air, pressurize altitude and even drinking water.

Organophosphates like TCP, found in contaminated cabin air, cause demalination of nerves, Professor Abou-Donia has shown, which lead to various symptoms, including severe headaches, constant pain and insomnia. TCP is even more toxic when heated to high levels, as occurs in-flight.

David Learmount, operations and safety editor of Flightglobal, compares the situation to the tobacco industry’s successful denial of a connection between smoking and lung cancer for decades. “Biochemistry/neurology are such complex medical fields that the lawyers can still find ways to stall the arguments, because the burden of proof is with those who are bringing the case, not with the industry, which says there is no case to answer,” said Learmount, who has been sounding the alarm about this issue on his safety blog.

Exxon Mobil spokesperson Christian Flathman responded to questions on whether its oils were safe for inhalation by pregnant women by citing a 2003 study on toxicity, which says that Mobil jet engine oils are safe “under normal conditions of use and with appropriate handling practices”. Flathman did not clarify whether Exxon Mobil considers events leading to contaminated air leaks as ‘normal conditions of use.

Air filtration company Purafil could filter out contaminants, according to director of business, Americas Unit, Chris Moon. He says, “Typically if you can identify and capture a contaminant, then you can filter it. Then it becomes a matter of – is it worth filtering, or is there another way to resolve this?”

Liebherr Aerospoace has designed and is currently testing an all-electric bleed-free air conditioning pack with Airbus, which would prevent any engine air from entering the cabin. Results are expected as part of the Clean Sky 2015 environmental initiative.


  1. The doctor who did the analysis also acknowledges that sensitivity to the “toxins” may have a significant variability by genetic disposition. In other words, it might be a bit like allergies. There are some people who have debilitating reactions when exposed to peanuts in a plane, too. Easier to treat that one, of course, but hard to say that this is a massive problem given the very, very, very low number of incidents.

    If it really is a genetic issue that seems like something to pursue just as much as the other bits.

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  3. John Lind

    Organophosphate poisoning from oil leaked into cabin air is not a rare occurrence. Many engines leak a small amount of oil at all times. This causes accumulation of toxins in tissues over time resulting in illness in some crew and passengers, arguably 12% to 15% of the population (NIH study of toxicant susceptibility). Immune system health may also be a factor. Mr. Westgate may never have suffered an actual fume event. Some feel ill but don’t know why. This problem is being deliberately ignored by the industry.

  4. In response to Seth’s point, the mistake that has been made by the industry so far (perhaps a convenient or deliberate error) is what scientists are now calling the LTLL (Long-Term-Low-Level) exposure. It is wholly overlooked. When a flight stops, the passengers get off, but the crew turn around and do it all again, day in day out. It is beyond belief that this effect has not been picked up by the industry-hired aviation medical professionals. There are now many studies pointing to the effects of LTLL. This acronym needs to be trumpeted from the rooftops time and again. This is why the overemphasis on documented fume events has been misleading – the seals leak all the time. As the leading engineer for General Electric said in a paper, “a leak-free seal is an oxymoron”. A complete abrogation of the”precautionary principle” of safety – Murphy’s Law, which says “if it can happen, it will happen”.

  5. As a medically (forced) grounded then retired ex flight attendant, the reasons for it being identified organophosphate poisoning from contaminated cabin air over longterm exposure ( 20 years) I can confirm the severe neurotoxic central nervous system damage caused ! There are no safe levels of neurotoxic chemicals ! The nowadays widely used nano particles contribute further to harmful so called low level exposure resulting in cellular and brain damage, as they can cross the blood brain barrier.

  6. Raoul

    This is very interesting. I was on an ERJ145 a few months ago in the middle US for about a 2.5 hour sector that I felt had fumes the entire flight. As a pax who flies 20-30 legs a year, I just thought it was my imagination, a lingering smell-memory from the boarding process, when it is certainly possible to have jetwash blow fumes into an open boarding door/open jetway on these little birds.

    I had not understood before this article that bleed air can come in contact with cabin air and that seals can fail. Now I think I wasn’t imagining the smell at all. The pilots and the one FA were flying the return sector … 5 or more hours exposed to that potentially bad air. Yikes.

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  8. Diana

    In August 2011, i flew six times in two weeks.. I woke one morning with severe vertigo, not being able to see and kept telling my husband I have been poisoned. My brain began to swell and no one could help me as they had no idea what has happened, I was sick in bed for nine months. I flew again to my father in laws funeral in feb 2013 and I collapsed when I got there from fatigue . I felt like I was in a dream, very removed from everyone. I have been told I have cfs and POTS but with known origin. My thyroud was completely destroyed. Had 18 Tumors inside of it and my neck had 100 lymph nodes removed with 22 cancerous tumors. Doctors at md Anderson keto asking me if I had been near a radiation explosion as they’ve never seen anything like this. My brain has been affected( cognotively I would say I suffer from some brain damage). In October 2914, I flew to hawaii from Sfo and felt very fatigued and angry when I got there, on the return flight, we landed and I immediately smelled fumes in our cabin. When I asked, they said it happens all the time! For the next two weeks, my doctors thought I suffered a stroke, fatigue, nauseam dizzy and the worst was not being able to comprehend what anyone was saying. Had mri, nothing showed up.all doctors are baffled. Is there help if indeed I’ve been poisoned?