What Are You Actually Breathing on Airplanes? (You May Not Like the Answer)

You may be inhaling toxic fumes during air travel and you might never even know it.

As you and about 10 million other Americans head out of town this week for the holidays, some of you may ask yourself this simple question: how are you able to breathe in an airplane 30,000 feet in the sky? And some of you might even ask a follow-up: exactly how safe is that air to breathe in the first place? Well, sorry to break it to you just before Christmas, but it turns out that the answers are: it’s complicated and not always.

How It Happens: The Environmental Control System

Warning–this is about to get technical. During the flight, air enters the cabin through the engines where it passes through the engine’s compressor. This highly pressurized air is used to conduct several mechanical processes necessary for running an aircraft like starting other engines, propulsion, maintaining proper cabin pressurization, and air conditioning.

However, unbeknownst to many, as the air passes through the engine’s compressors, the engine oil seals can leak toxic fluids into the cabin’s air supply.

“If you were to take a urine sample of all the passengers after a flight, you’d be amazed at how all the volatile organic compounds that come from the oil of the turbine are actually all in [the passengers’] bodies,” said Dr. Michel Mulder over FaceTime from his home in the Netherlands. Mulder is a former KLM airline pilot turned doctor who’s dedicated his life to studying the negative health effects of exposure to these toxic engine oils, or “aerotoxic syndrome,” as he calls it.

Mulder argues that if you belong to a group of individuals that are unable to break down volatile organic compounds, or VOCs, from the engine fluids properly, your body will be carrying toxins that cause central nervous system and neurodegenerative damage akin to nerve poisoning. The symptoms of exposure include difficulty breathing, fatigue, and muscle exhaustion–with symptoms worsening from repeated exposure (aka frequent flying).

“I’ve seen in my medical practice about 250 airline personnel, cabin and cockpit, who are severely affected,” said Mulder.

The Case of the 43-Year-Old Pilot

One of the additives in turbine oil is an organophosphate, which falls into the category of nerve gas (you know–the chemical warfare agent).

In a 2014 study, Mulder and a team of scientists examined the premature death of an otherwise healthy 43-year-old commercial airline pilot. From 1999 to 2012, the pilot had been experiencing various constant pains, yet his illness was never properly diagnosed. In 2008, the first signs of neurological deficits were seen in the form of numbness in his hands and feet. From the report: “Just before death the subject attributed his symptoms to repeated exposure to engine oil fumes during the course of his employment as a commercial airline pilot.”

During the autopsy, Mulder and his team noticed signs of neuronal cell degeneration in the pilot’s blood, and his brain and spinal tissue showed additional degeneration. The report concluded that his symptoms “were not only consistent with but also identical to, known and documented effects of organophosphate poisoning.”

What’s equally as chilling as the prospect of being poisoned on your next flight is the fact that you might not know that you were poisoned in the first place–organophosphate poisoning is slow-acting in nature, and it was only from the pilot’s cumulative, low-level exposure to the toxins over time that his symptoms became evident at all. According to Mulder and his team’s report, sensitivity to organophosphate-induced neurotoxicity is dependent on the presence of certain enzymes that detoxify, or break down, the toxins. He claims that only 30% of all people possess certain genetic variants that make them less able to break these toxins down.

So, Who’s to Blame?

“If anything, I blame the FAA the most because they are the regulator most responsible for flight safety and flight attendant health,” said Judith Anderson, an industrial hygienist with the Association of Flight Attendants, the union that represents flight attendants in the United States. They have a helpful slideshow that provides an action plan for passengers who suspect a fume event is occurring on their flight. 

While a wealth of information exists on the signs of contaminated cabin air supply, no one’s making the flight attendants visit the AFA’s webpage. “There needs to be a requirement that airlines include fume events in their initial and recurrent training for crews,” said Anderson.

And the airline industry and FAA have been well aware of this problem. In 1955, Henry A. Reddall of North American Aviation presented a paper on the elimination of engine bleed air contamination to the Society of American Engineers. He stated plainly: “External leakage of oil or other fluids wherein such fluids can leak into the engine air inlet can also cause contamination.” 

Confused? Correct!

Another thing that makes engine bleed air contamination hard to figure out is that it’s easy to confuse the symptoms of exposure to organophosphates with the general woes of air travel. Feeling extra sluggish? You’re jet-lagged. Stomach’s hurting? It’s probably the airplane food. Or! You could have breathed contaminated air. Who knows? Sorry.

Currently, the burden of proving you were contaminated rests solely in the hands of the individual. People like Anderson and Mulder take it upon themselves to educate the general public about exposure to these engine fumes when the airline industry and FAA should put formal measures in place to prevent exposure and educate flight attendants.

Yes, of Course, There Are Lawsuits

There is ongoing litigation in several countries related to toxic cabin air. In the UK, the Unite Union, a work union that represents airline attendants, is suing British Airways, EasyJet, Virgin Atlantic, Thomas Cook, and Jet2 over the claim that cabin crew and pilots are regularly exposed to toxic fumes during flights. In the US, a class-action lawsuit was filed in 2018 against Frontier Airlines for refusing to acknowledge a dangerous fume event.

It seems people are wisening up to the fact that the constantly recirculated cabin air in commercial airplanes might not be the best thing to inhale. Just this past April, House Democrats introduced the Cabin Air Safety Act of 2019 which seeks to “improve the safety of the air supply on commercial aircraft.”

It’s only a matter of time before all aircraft become like Boeing’s Dreamliner 787, the company’s newest model and its first to boast of a “no-bleed system.” Unfortunately, it won’t be in time for this year’s holiday rush.