Toxic cabin air breathed by passengers, pilots and cabin crew is linked to cancer, chronic fatigue and neurological problems, according to new research in a World Health Organisation (WHO) journal.

The Public Health Panorama report into so-called aerotoxic syndrome - the name given to the health effects of exposure to bleed air, used to pressurise aircraft cabins, that has been contaminated with chemicals such as engine oil - found a clear link between both short- and long-term symptoms and illnesses and toxic fume events.

It said that in 2015 more than 3.5 billion passengers and 500,000 pilots and cabin crew were exposed to low levels of engine oils in the air.

“Aircraft air supplies contaminated by pyrolysed engine oil and other aircraft fluids can reasonably be linked to acute and chronic symptoms, findings and diagnoses, thus establishing causation,” read the report, authored by Susan Michaelis from the University of Stirling, in association with Vyvyan Howard from the University of Ulster and Jonathan Burdon, a consultant respiratory physician from Melbourne.

“Both acute and chronic exposures to neurotoxic and a wide range of thermally degraded substances were confirmed, along with a clear pattern of acute and chronic adverse effects.”

The study looked at more than 200 airline workers who had been exposed to toxic cabin air and found a variety of health effects, including eye, nose and throat irritations, skin reactions, recurrent respiratory tract infections and fatigue, nausea and cramps.

Other diagnoses included “cardiovascular, neurobehavioural, neurological and respiratory symptoms, chronic fatigue, multiple chemical sensitivity, aerotoxic syndrome, cancer, soft tissue damage and chemical exposure”.

The report also examined the immediate impact that toxic fume events can have on staff. Studying 15 circumstances where contaminated air had filled the cabin, the researchers found that the pilot or pilots were fully or partially incapacitated on seven occasions. On five of the occasions, both pilots suffered full or partial “incapacitation”.

Ms Michaelis concluded: “There is an obvious need for a clearly defined internationally recognised medical protocol, occupational syndrome and disease recognition.”

The issue of contaminated cabin air has become increasingly controversial as a number of campaigners push for more to be done to protect airline staff and passengers, while aviation authorities maintain it is safe.

The Civil Aviation Authority (CAA) has always said that there is no evidence of long-term health effects.

A spokesperson for the CAA said: “Our priority is always the safety of passengers and crew and we continue to work with airlines, manufacturers and international regulators to drive improvements in safety standards across the industry.

Passengers and aircrew have been incapacitated by toxic cabin air Credit: Credit: RosaIreneBetancourt 7 / Alamy Stock Photo/RosaIreneBetancourt 7 / Alamy Stock Photo

“We understand the concerns that have been raised about cabin air quality and we take very seriously any suggestions that people have suffered ill health from their experience of aviation.

“We rely on guidance from scientific experts based on the results of a number of independent studies and evidence reviews - including Government commissioned research. Long term ill health due to any toxic effect from cabin air is understood to be unlikely, although such a link cannot be ruled out.

“A recent study commissioned by the European Aviation Safety Agency (EASA), which maintains responsibility for approving the safety of aircraft and setting aviation standards for European airlines, concluded that the air quality on flights it tested was similar or better than that observed in normal indoor environments.

“We continue to support steps to further develop understanding of air quality on board aircraft, including a further research by the European Commission being undertaken in conjunction with EASA.”

Unite, the union, said last year it was pursuing 67 legal cases against UK airlines on behalf of former and serving cabin crew who say they have been affected by contaminated cabin air.

Telegraph logo This video content is no longer available To watch The Telegraph's latest video content please visit youtube.com/telegraph

Last year, British Airways was accused of downplaying a fume incident that left 25 cabin crew in hospital.

A spokesperson for BA said at the time: “Safety is always our priority. There has been no change in the way in which we investigate reports of this nature.

“We continue to conduct thorough and detailed investigations which we share with the CAA. We always encourage our people to report any potential incident to allow us to investigate them.”