There is a particular unease that comes from seeing that an ordinary part of life has been linked to cancer. If you fly a few times a year, the results of a new study by two of us may elicit exactly that feeling; pilots and flight attendants die of radiation-related cancers at higher rates than workers in over 500 occupations that we studied.
So should you rethink your travel plans? We aren’t, and we don’t think you should, either. Understanding why can teach us a lot about how to read health headlines like this one.
Commercial jets cruise at altitudes above 30,000 feet, where the atmosphere is thin, allowing for higher speeds and engine efficiency. But the thinner atmosphere offers less shielding from cosmic radiation (in the form of high-energy particles that stream in from the sun and from deep space) than we enjoy closer to sea level.
Spending hundreds of hours among the clouds each year, air crew absorb more radiation, on average, than workers in any other job in the U.S.—including those generating nuclear power and our colleagues who work with radiation for medical purposes. This type of ionizing radiation, in sufficient doses, can damage DNA and give rise to cancer. What has never been clear is whether the amount aircrew accumulate over a career is enough to increase cancer risk above other occupations.
In a new study published in JAMA Internal Medicine, we set out to find that mark. Using federal data on nearly every death in the U.S., newly linked to each person’s usual occupation, we examined more than 12.7 million deaths from 2020 to 2024 (a majority of deaths among adults) across 503 occupations—an approach that earlier studies, which had mortality data on air crew but no other occupations, could not take.
The approach rested on simple logic. If cosmic radiation were truly driving cancer among air crew, the signal should appear specifically in the cancers that radiation is known to cause (breast, prostate, melanoma, and certain leukemias), and the signal should not appear in cancers like colon cancer that aren’t caused by this type of radiation. We would also expect to see higher rates of radiation-associated cancers among other types of workers exposed to radiation, like nuclear technologists. Meanwhile, unless something about aviation other than flying was associated with these cancers, we wouldn’t expect to see higher rates in aviation workers who remain on the ground, like aircraft mechanics and assemblers.
The pattern was hard to miss. Among all 503 occupations, flight attendants and pilots had the highest and second-highest share of deaths from radiation-related cancers—6.9% and 6.7%, respectively, after accounting for differences in age, sex, and other factors—a proportion that exceeded that of nuclear technologists. For cancers unrelated to radiation, aircrew sat near the middle of the pack. And our comparison groups fell exactly where the radiation hypothesis predicted; nuclear technologists ranked near the top, while ground-based aviation workers did not.
That internal consistency—seeing the types of cancers we expected in the workers we predicted would be most at risk, with control groups behaving precisely as expected—makes it unlikely that the pattern arose by chance. But as striking as these patterns are, this study, by itself, is not iron-clad proof of cause and effect. Our data cannot measure how much radiation any individual actually received. Occupations are sometimes recorded incorrectly on death certificates. People at higher baseline risk for this type of cancer may be more likely to work as pilots or flight attendants. Air crew face other hazards, from disrupted circadian rhythms to in-cabin exposures, that we could not fully account for.
Importantly, the study does not say that your next flight, or even a lifetime of flying for annual vacations, meaningfully raises your risk of cancer. The signal we detected generally reflects an entire career spent in the skies. To put this in perspective, pilots and flight attendants accrue an estimated 3 to 6 millisieverts of cosmic radiation each year, decade after decade. A traveler who takes 10 cross-country round-trip flights a year absorbs only about 0.4 millisieverts—roughly a seventh to 1/15 of what an aircrew member accrues in a single year, and only over a few years of heavy travel rather than an entire working life.
If anyone should take note, then, it is not passengers but the agencies charged with protecting the people who work at altitude. The Federal Aviation Administration already recognizes aircrew as occupationally exposed to radiation. Yet unlike nuclear workers, or air crew in Europe, U.S. pilots and flight attendants are subject to no federal dose limits and no requirement that their exposure even be monitored.
While our findings are unable to determine how large the risk is for any individual crew member, they do suggest that the workers who absorb the most radiation of any occupation in the country deserve the same basic protections we extend to everyone else who works around it.
So the next time a flight attendant hands you a coffee at 30,000 feet, there’s no need to fret over the tiny radiation dose you are taking on by being up in the sky. But do consider the doses they take on, day after day, and whether we are doing enough to look after the people who spend their careers somewhere the rest of us are only passing through.
