A new study has found that pilots and flight crews on commercial airlines seem to have almost double the risk of getting skin cancer.

Published in JAMA Dermatology, the study was unable to determine what caused this hike in risk for flight attendants and pilots. Researchers believe it is possible that the higher concentration of UV rays in the air could contribute, but not enough data has been collected to establish if this is the cause.

Dr. Susana Ortiz-Urda, lead author of the study and co-director for the UCSF Melanoma Center at the University of California in San Francisco, finds the statistics troubling.

Melanoma is a deadly form of skin cancer that affects tens of thousands of people each year in the United States. Otiz-Urda feels that more should be done to by the Federal Aviation Administration (FAA) to protect pilots and crew from the increased intensity of the sun’s rays that far in the air.

UV radiation increases in intensity 15 percent every 900 meters above sea level. At 9,000 meters, or 29,527 feet, above sea level the intensity has basically doubled, the study claims.

Ortiz-Urda thinks that a likely source of UV exposure comes from windows made of glass that do not offer the same protection from UVA rays that plastic glass offers. She has issued a call to action for the FAA to address the situation in hopes of reducing the risk for those working on planes.

There is some contention about her findings regarding UV exposure in the air. Experts in risk assessment for planes and their crews claim that the windows are already designed to ward off harmful rays. An alternative possible explanation offered by these experts is that pilots and crews fly more frequently to sunny areas and engage in more tanning, thereby getting more burns.

But the study’s authors point out that there is other research that has examined this exact possibility and found no statistically significant difference between the tanning-related behaviors of pilots, crews and other populations.