I hate airplane travel but at the same time I’ve never been worried that the air inside the cabin was slowly poisoning me. Others, however, have wondered whether air in plane cabins might be toxic, especially crews that are exposed to this particular type of air more consistently than travelers.
An article in The Conversation explains how air is generated at high altitudes, and how, on occasion, it might be toxic for anyone inside an aircraft cabin, although there’s no definitive proof on the matter because air quality isn’t properly monitored.
Symptoms — including irritation to the eyes, nose and throat, headaches, light-headedness and dizziness, fatigue, weakness, generally feeling unwell, confusion and difficulties in concentration — may be reported by people who have been exposed to contaminated air, especially pilots and crew.
The symptoms may be the result of exposure to the organophosphate known as tricresyl phosphate (TCP) which is a flame retardant additive in jet engine oil and hydraulic fluids that can cause certain medical issues – in fact, organophosphates have been used as nerve gas agents in World War II so it’s already known what they can do to the nervous system in very concentrated doses.
The Conversation also explains how exposure would occur. Every airplane needs to provide breathable air to travelers and crew. That happens by taking air from outside, and heating it up to breathable levels – that means at around 15°C at a pressure of 14.7psi. But at 35,000 feet the air is very cold (-50°C) and only has a pressure of 3.46psi. To heat it up, the air goes through the engines.
“As part of the propulsion process, aeroplane engines heat and compress air before fuel is added and combusted,” the publication explains. “On most aircraft this air is then ‘bled off’ and pumped into the aircraft, unfiltered. Ordinarily this process is relatively safe. But occasionally faulty seals can result in contamination by allowing heated and broken down engine oil fumes to escape into the airflow.
The full article further details some of the various cases of suspected air contamination instances, what has been done about it, and what studies say (see source link below). While the conclusion seems to be that it’s not perfectly clear whether there are definitive issues with airplane cabin air, especially for flight attendants and pilots, the European Aviation Safety Agency is looking at adding on-board instruments that would measure air quality in real time in the future, so better answers might be provided soon.