Flying a plane should come with a hazard warning, according to researchers, after a study found a link between contaminated air and the health of the crew.

A new study led by the University of Stirling is said to be the first of its kind to look in depth at the health of those suspected to have been exposed to contaminated air during their work.

It showed a clear link between being exposed to air supplies contaminated by engine oil and other aircraft fluids, and a variety of health problems, researchers said.

The scientists examined more than 200 aircrew and found many had been exposed to a number of substances through aircrafts’ contaminated air.

They uncovered a clear pattern of acute and chronic symptoms, ranging from headaches and dizziness to breathing and vision problems.

One test looked at pilots’ health and showed 88% of the 219 people examined were aware of exposure to contaminated air.

Almost 65% reported specific health effects while 13% had died or experienced chronic ill health.

Another test looked at 15 specific oil leak incidents. Some 80% involved fumes only and all of the events took place when the aircraft was preparing for, or in, flight, researchers said.

Ninety-three per cent of the incidents involved symptoms ranging from in-flight impairment to incapacitation and almost 75% included adverse symptoms in more than one crew member, with anywhere between 10 and 23 different symptoms reported in relation to almost half of the events.

Dr Susan Michaelis, of the University of Stirling’s occupational and environmental health research group, said: “This research provides very significant findings relevant to all aircraft workers and passengers globally.

“There is a clear cause-and-effect relationship linking health effects to a design feature that allows the aircraft air supply to become contaminated by engine oils and other fluids in normal flight.

“This is a clear occupational and public health issue with direct flight-safety consequences.”