A toxic air event is just as scary as it sounds: An instance where fumes from jet engine oil or other gases leak into the cabin (or cockpit) on a flight, and are inhaled by passengers and crew. Exposure in just one event can cause long-lasting health issues.
But researchers and airline employees contend that such leaks occur much more than is reported by the Federal Aviation Administration, and are warning the public about the risk.
What are the details?
KPIX-TV reported on a situation that occurred on July 16, when a pilot made an emergency landing in Kansas City, reporting to the control tower that passengers were getting ill.
Speaking on the condition of anonymity out of fear of losing her job, a flight attendant told KPIX, "People were being hospitalized. My understanding is that the crew felt symptoms of nausea, itching throat. That is what caused the diversion."
But the incident on July 16 was never reported to the FAA because, the flight attendant said, the airline wants to cover up fume events.
According to a 2014 study funded by the FAA, co-author Dr. Robert Harrison, toxic air events are underreported.
"We did a large survey of flight attendants, found a pretty high prevalence of symptoms, and uncovered the iceberg, if you will, below the surface" he told KPIX.
"There's a large number of flight attendants who had symptoms but had never reported them," he added.
Harrison also noted that passengers who have symptoms "may not be aware" that they had been exposed to fumes, and therefore attribute the effects to another source, and therefore such instances go unreported.
To give further perspective, the FAA claims that fume events occur in less than 33 out of a million flights. But according to aviation attorney and pilot Mike Danko, "Most studies suggest that we get about five fume events per day in the U.S."
What about the lawsuits?
Airline workers have launched a slew of lawsuits against their employers and plane manufacturers for damages from continued exposure to toxic fumes on flights, including a 2015 suit against Alaska Airlines by a group of flight attendants who alleged the company knowingly allowing hazardous air into cabins.
In a report last year, Flyertalk's Jeff Edwards said that fume events "used to seem like a rare and mysterious occurrence." But now, he wrote, "labor leaders and regulators say that toxic air events and the accompanying Aerotoxic Syndrome have become all too commonplace."
The flight attendant who spoke to KPIX concluded, "Instances are still happening, so I don't think they are really doing much. I just want people to be aware that when they are exhibiting symptoms that they don't normally exhibit, especially if they are frequent fliers, to get themselves checked out."