Airline pilots and cabin crew are twice as likely to suffer from skin cancer because of regular exposure to harmful ultraviolet rays from the sun at high altitude, US researchers said.
Analysis of 19 studies involving more than 266,000 people found that incidence of melanoma was between 2.21 and 2.22 higher for pilots and 2.09 greater for flight attendants, or more than twice the rate of the general population.
The incidence rate was attributed to ultraviolet rays filtering into planes at high altitude through cockpit windscreens and windows on the fuselage, the author of the meta-study published on Wednesday said.
Dr Martina Sanlorenzo, from the University of California at San Francisco, said the study had "important implications for occupational health and protection of this population".
The study appeared in the Journal of the American Medical Association Dermatology.
Researchers reported that at 9,000 metres above sea level, the cruising altitude of most commercial jets, carcinogenic ultraviolet rays were twice as powerful. The levels were even higher when planes fly over thick cloud layers, which reflect up to 85 per cent of the harmful rays back towards a plane.