New report suggests that high ozone combined with low humidity may be behind the common health problems reported by cabin crew and pilots. (Photo: Shutterstock)
New report suggests that high ozone combined with low humidity may be behind the common health problems reported by cabin crew and pilots. (Photo: Shutterstock)

Ozone may be the cause of health problems among airline crew

Pilots and flight attendants have long complained about health problems. New study suggests that high ozone levels and low cabin humidity might be to blame.

In 2012, 43-year-old pilot Richard Westgate died after years of ill health, which he attributed to breathing toxic fumes while flying. Before his death, he had complained of headaches, mental confusion, and insomnia, and instructed lawyers to sue British Airways over health and safety breaches.

Since then, at least 17 current and former cabin crew employees have launched legal proceedings against the company, for the health problems that they attribute to poor air quality and ventilation within the cabin. They believe that they inhaled air contaminated by engine oil and other toxic chemicals.

But now, a new study suggests that high ozone levels and poor cabin air quality could be to blame. The scientists behind the study searched the scientific literature and saw that in some cases the ozone was as up to three times higher than the recommended limits set by the World Health Organisation (WHO).

“The ozone and the chemistry of the aircraft cabin may under certain circumstances be instrumental in causing mucosal irritation, especially if the ozone level becomes too high, and especially if relative humidity [of the cabin air] is too low,” says lead-author Peder Wolkoff, adjunct professor at the Department of Chemistry, the University of Copenhagen, Denmark.

Pawel Wargocki, an indoor air quality scientist from the Danish Technical University (DTU) was not involved with the study himself, but he is impressed with the new results.

“I think it’s an outstanding study and it’s fantastic to see that Peder [Wolkoff] has tried to collect all the literature,” says Wargocki.

Surprisingly high ozone levels in the aircraft cabin

Wolkoff and colleagues compared the air quality data in aircraft cabins with similar indoor climate data available in office environments where workers often complain of similar health problems.

They discovered that low humidity and high ozone could be the culprit.

Wolkoff points to an earlier study, which found that ozone levels in some cabins were three times higher than the recommended safe limits of 100 micrograms per cubic metre.

"[Ozone] is a lung irritant, but there may also be some combined effects. The low humidity makes the mucous membranes, especially the eyes, more vulnerable to the substances formed when ozone reacts with some chemical constituents in the air. They form strong mucosal irritants, formaldehyde, and acrolein, which irritates the throat and eyes," said Wolkoff, adding that not all aircraft are constantly affected by very high levels of ozone.

While passengers come and go, airline staff may be exposed to high levels of ozone on a daily basis, he says.

“Several assessments have shown that it’s unlikely that [ozone] levels are this high in every aircraft on a daily basis. The cases that we’re talking about are where levels are extremely high, and it could mean that flight personnel experience poor indoor air quality in the cabin. The longer they’re in the cabin, the greater the complaint rate," says Wolkoff.

Colleague: An important study

Wolfgang Rosenberger, head of laboratory at the Institute of Occupational Medicine at Hannover Medical School, Germany, praises the new study.
"In my opinion, Wolkoff and his colleagues' work is a good overview of the problem and it’s a good contribution to analyse the subject objectively. It’s extremely important to avoid both exaggeration and understatements," writes Rosenberger in an e-mail to Science Nordic.

He says the study opens up opportunities to investigate substances not previously considered.

"This study is important in terms of looking at the issue objectively. Moreover, it also creates an incentive to extend the perspective, for example, by also looking at other substances such as reaction products of ozone, which haven’t been considered previously," he said.



Read the Danish version of this story on

Translated by: Catherine Jex

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