Pilots are left incapacitated or suffering fatigue, experiencing breathing problems, and stomach and heart trouble. It’s called aerotoxic syndrome, and researchers are calling for it to be recognized as an occupational disorder. A study published June 12, in the World Health Organization’s journal Public Health Panorama, focused on “bleed air” – the system in use on most planes by which unfiltered air from engine compressors is used to supply the ventilation system in the cabin and cockpit. In a survey 142 out of 274 UK pilots reported specific symptoms and diagnoses with 30 suffering “adverse health effects.”
Thirty-six of the pilots later died or had chronic ill health leading to a permanent loss of fitness to fly. A second report on 15 potential incidents said: “In all, 53% of events included long-term adverse effects for one or more crew members.” In one third of the cases both pilots were affected. Passengers were affected in 27% of cases.
In 1999, three scientists investigating the ill health many aircrew suffered from came up with the name Aerotoxic Syndrome to describe the different symptoms being experienced after some flights. It was discovered that not only were there toxic chemicals present in modern synthetic jet engine oils, but that those toxins were passing unfiltered into the aircraft cabins, affecting the air that crew and passengers breathe in.
One of the chemicals giving rise to the most concern is tricresyl phosphate (TCP), which is an organophosphate, the family of chemicals originally designed as nerve agents for warfare. This is added to the engine oil as an anti-wear agent, necessary because of the extreme temperatures at which the engines operate.
Since warm air is needed for engine propulsion and for passengers to breathe, it was decided to combine the two and bring the air through the engine to heat it, then ‘bleed’ it off and pass it unfiltered into the cabin. There are seals in the engine intended to keep oil out but unfortunately they require air pressure to keep the seal tight, and at times they allow contaminated air to pass into the cabin. Sometimes if the seal is worn or faulty or if the oil is leaking, large amounts can pass into the air supply and these are known in the industry as ‘fume events.’
No aircraft currently flying has any form of detection system fitted to warn when these events occur.
According to David Learmount, Operations and Safety Editor of Flight International, the airlines are doing everything they can to deny this problem.
Even when the crew know and report the fume event, no one is ever directed to tell the passengers. Signs to look out for include lots of people coughing (who weren’t coughing before take-off) and others fainting or becoming unwell. Sometimes a ‘mist’ can be seen in the cabin. Although some fume events are odorless, you should look out for the smell of engine oil, which is often described as a musty smell similar to sweaty socks or an old wet dog.
Most common symptoms are sore throats, cough, sore nose, nose bleeds, migraine, headache, flu-like feeling, nausea, vomiting, diarrhea, muscle aches, fatigue and breathing difficulties.
If you are concerned about this problem, retired BA pilot John Hoyte suggests, “purchasing a face mask with a carbon-activated filter before your flight and wear it for the duration. According to health expert Raymond Francis, the best way to avoid getting ill is to take 1 gram of vitamin C every hour you are in the air.”
“To this day, the only thing filtering this toxic soup out of the cabin are the lungs of the passengers and crew.” Aviation Attorney Alisa Brodkowitz