By Allan Chernoff, CNN
(CNN) – Could the air on board your next flight be toxic?
Cabin ventilation air comes through the engine. So, if there's an oil leak, engine oil mist – containing neurotoxins – can seep into the aircraft. Though relatively rare, it has happened on commercial flights, triggering neurological symptoms like severe headaches, tremors, and dizziness in crew members and passengers.
CNN recently tested the air on board a transcontinental flight. (We're not going to mention the airline because this is an issue affecting all airlines.)
Toxicologist Chris van Netten of the University of British Columbia, who has studied air quality on board planes for years, provided CNN with two portable air monitors. They use small fans to blow air through a filter which can capture contaminants.
On board, I don't sense anything unusual about the air in the cabin, aside from the typical airplane dryness. Once the plane is at cruising altitude I turn on the monitors, which run for about 90-minutes on battery power.
If there are toxins in the air, they should leave residue on surfaces of the cabin. So, wearing a plastic glove, I wipe the cabin wall and tray table back with sterile alcohol swabs which I then store in plastic zip-lock bags.
Shortly after our flight, I’m in a laboratory at The University of British Columbia, presenting the samples to Professor Van Netten, who places our air filters and alcohol swabs into test tubes. His research associate, Tim Ma, adds solvent to extract whatever chemicals the filters and swabs captured. The scientists also analyze strands of producer Laura Dolan's hair to see if it collected toxins from her seat back cushion.
Ma runs the resulting chemical mix through a mass spectrometer, a device that measures molecular weight and chemical composition. It's able to compare our samples to the compound Tricresyl Phosphate, a neurotoxin known as "TCP," which is in engine oil.
The finding: our swabs of the air cabin surface do contain TCP!
"It's the pattern that really nails it down to actual engine oil. This is the pattern you find in engine oil and this is the sample in the swab sample you took from the aircraft," says van Netten, pointing to a computer monitor displaying virtually identical valleys and peaks, measurements of the weight and structure of Tricresyl Phosphate. "It's like a signature. You can't be mistaken about it."
Tim Ma has analyzed surface swabs from 40 different flights. He almost always finds TCP. "The wipes are at significant levels," says Ma.
Significant, but not large. The biggest amount we find is only 44-billionth of a gram.
So, if I were to drop some food on the tray table, then eat off of it, would I be putting myself in danger? Van Netten says no, there would be no health consequences.
"The amount is likely to be relatively low, so there's no point getting all excited about that," he says.
Our air samples do not show any trace of TCP. That means toxic residue has collected on the surface of the cabin from either a prior fume event or from gradual, continual accumulation of toxins.
"There is a fair amount of remnant material floating around literally in the ventilation system which comes out on a regular basis and that's what you're measuring," says the professor. "The Tricresyl Phosphate will stick around for a heck of a long time. They don't deteriorate it seems."
Van Netten explains his research shows when engines are shut down some oil can leak overnight. In the morning when pilots turn on the engine, a mist of oil can spread through the cabin.
Laura's hair shows traces of TCP as well, apparently picked up from the airplane seat. But, the amount is only one-trillionth of a gram.
The two leading aircraft manufacturers – Boeing and Airbus, which both use the same ventilation system – acknowledge "fume events" can occur. But they say their planes deliver good quality air.
"The cabin air system in today's jetliners is designed to provide a safe, comfortable cabin environment," said Boeing.
"Airbus aircraft are designed to guarantee a proper cabin air quality under normal operations," said Martin Fendt, spokesman for the aircraft-building division of the European Aeronautic Defence and Space Company.