Commercial aircraft routinely cruise above 30,000 feet, where the atmosphere is thinner and provides less shielding from cosmic radiation originating in space. For most passengers, exposure during an individual flight remains low. But for pilots and flight attendants who spend thousands of hours in the air over many years, that exposure can accumulate.

A new study published in JAMA Internal Medicine on August 17 has drawn attention to this occupational exposure after finding that pilots and flight attendants had among the highest proportions of deaths from cancers associated with radiation across more than 500 occupations. The study found that 6.9% of deaths among flight attendants and 6.7% among pilots were from radiation-related cancers, compared with 5% among workers overall.

However, the findings show an association, not proof that cosmic radiation alone caused these cancers. Other occupational factors, including disrupted sleep and circadian rhythms, may also play a role.

Why are pilots and cabin crew exposed to more radiation?

“The atmosphere is thinner at cruising altitude and offers less protection from cosmic ionising radiation from space. That’s how aircrew get more radiation than people on the ground,” said Dr Amit Upadhyay, Senior Consultant Haematologist and Oncologist, PSRI Hospital.

Ionising radiation can damage DNA. While the body can repair much of this damage, repeated exposure over many years may increase the possibility of mutations that contribute to cancer. Dr Upadhyay stressed that the exposure from any one flight is low, but it can accumulate over a career.

The National Academies’ 2026 report similarly notes that aircrew radiation exposure varies according to factors such as altitude, latitude, flight duration and solar activity, with doses accumulating over a career.

Which cancers are of concern?

The cancers relevant to the new study include leukaemia, lymphoma, multiple myeloma, melanoma and other skin cancers, as well as breast, thyroid and some central nervous system cancers.

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Dr Upadhyay, however, cautioned against attributing these cancers solely to cosmic radiation. “The new study suggests an association with radiation-related cancer mortality and does not prove that cosmic radiation alone caused these cancers,” he said.

This distinction is important because aircrew have other potential occupational exposures. The CDC notes that, alongside cosmic ionising radiation, disrupted circadian rhythms from crossing time zones and working at night may also be relevant to cancer risk.

There is also previous evidence of higher melanoma incidence among pilots and cabin crew, although researchers have noted that factors beyond cosmic radiation may contribute.

Experts on cancer risk at 30,000 feet (Photo: Magnific

Should frequent flyers be worried?

For passengers, the situation is different. A person who flies occasionally, or even relatively frequently, generally accumulates far less exposure than someone who spends decades working onboard aircraft.

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“For a passenger who travels from time to time or even one who travels frequently, the amount of exposure from each flight is fairly small when compared to the total exposure experienced by professional aircrew over many years of regular flying,” said Dr Anil Heroor, Director – Oncological Sciences, KIMS Hospitals, Thane.

Dr Upadhyay estimates that frequent flyers may receive around 0.4 mSv of cosmic radiation per year, compared with approximately 3–6 mSv for flight crew, depending on routes. He said that while exposure increases with the number, duration and altitude of flights, the average traveller has little reason to be concerned about developing cancer because of flying.

What can aircrew do?

Dr Upadhyay said airlines and regulators should ideally estimate and monitor cumulative radiation exposure, particularly among crew who regularly operate long-haul, high-latitude or polar routes. Where operationally feasible, reducing time spent on routes associated with greater exposure could also help.

Dr Heroor similarly said airlines could consider route planning and operational measures to minimise unnecessary cumulative exposure. He also highlighted the importance of routine medical examinations and age-, sex- and risk-appropriate cancer screening.

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“Having occupational radiation monitoring in place and setting clear exposure limits can help to identify those workers who accumulate higher doses and aid in better long-term risk management,” Dr Heroor said.

The 2026 National Academies report also calls for stronger monitoring, communication and mitigation strategies around occupational radiation exposure among flight crews.