A growing number of flight attendants and pilots want answers from airlines about what they say is toxic air on board flights. They argue this is causing serious health damage. Andreas Becker investigated their claims.

Flight attendant Kerstin Konrad still remembers her first “fume event” – as the industry calls air inside the aircraft that is possibly contaminated.

“On the flight, passengers were asking for headache tablets,” Konrad told DW.

Passengers had noticed a peculiar smell at the back of the plane and the captain asked her to check it out, she says. “I went back and sniffed the air nozzle.”

“I immediately got a headache and a tingling sensation in my limbs that spread like numbness.” She says she then became dazed and so confused she could not perform even the simplest task. “I could not sort the juices on the trolley anymore, which sounds crazy.”

Konrad says that since 2013 she has experienced a total of four such fume events, sometimes accompanied by odd smells, sometimes without. She says she has on each occasion had headaches and abdominal pain, numbness and confusion and has also suffered permanent health damage meaning she can no longer fly. She has nerve damage and restricted lung functions, both confirmed by a doctor.

Konrad has become an activist in fume events, organizing petitions and demonstrations with others, most recently at the beginning of September in front of the Reichstag building in Berlin.

And she is not alone. Some 228 such fume events were reported to the German Federal Bureau of Aircraft Accident Investigation (BfU) in 2016 alone.

And the number of cases reported by pilots and cabin staff to their employers may be even higher, according to TV channel ZDF, referring to internal records held by the airlines, some of which are not passed on to the BfU.

What is a dangerous level? 

The German Flight Accident Investigation Act and an EU regulation determine what constitutes near-accidents, which need to be investigated by authorities. Here, the situation in the cockpit is crucial.

“Circumstances that force a pilot to use an oxygen mask are what can lead to a serious incident,” Jens Friedemann, an accident inspector at the Federal Bureau of Aircraft Accident Investigation (BfU), told DW.

Using these criteria for the 228 fume events reported last year only two were considered serious incidents. In other words, there is no fundamental, and above all no particularly pressing, problem.

Contested cause and effect 

But others are less certain. Doctor Astrid Heutelbeck told DW, for example, that she can prove a causal connection using residues in the blood and urine of people who have suffered a fume event, by using a procedure called human biomonitoring.

“In human biomonitoring — in connection with the time of the event — we find substances and groups of substances that are not described as components of the normal environment, but as the ingredients of kerosene, oils or hydraulic fluid,” Heutelbeck said.

It is proven that these substances can damage the nervous system and the lungs, Heutelbeck, who is the head of the work and environmental medicine outpatient department of the Göttingen University Medical Center, believes.

The air in the cabin is tapped from the turbines of the aircraft; it is also called bleed air. But it may possibly be contaminated with constituents of kerosene, oil or hydraulic fluid.

“People can still inhale and exhale the same amount of air as everyone else. That’s not a problem, but to get the oxygen out of this air does not work anymore and they notice it in terms of physical strain. When they go upstairs, for example, people may say they feel like grandma.”

Since the beginning of 2014, Heutelbeck has investigated “several hundred” patients from the aviation industry with these symptoms, using standardized medical procedures and ruling out other pathologies.

‘No evidence’ 

The aviation industry, meanwhile, is dragging its feet.

It has yet to recognize a scientifically proven link between the above outlined symptoms and what is called the bleeding of toxic air into plane cabins.

“The bleed-air system has been standard in the aviation industry since the 1960s and has proven to be reliable,” Claudia Nehring of the Federal Association of German Air Transport (BdL), representing the interests of airlines and airport operators, told DW.

“In addition, the air is drawn off in front of the combustion chamber of the engine – the kerosene injection and the combustion take place later, which means that it is technically impossible that the air is connected with exhaust gases or residues from the combustion chamber,” she goes on.

“There are different studies that have examined the quality of cabin air,” she says. “None of them has demonstrated that cabin air is contaminated in such a way as to cause health damage.”

The European Aviation Safety Agency (EASA) has also air-tested plane cabins for toxic substances in two studies and found that air quality in the aircraft is no worse than that in normal offices.