Cosmic Radiation Exposure During Air Travel and in Space
Editorial revision 2026
Cosmic Radiation Exposure During Air Travel and in Space
The atmosphere and the Earth’s magnetic field act as a shield against radiation from the Sun and the stars. The layers of the atmosphere absorb most of the secondary particles generated by the impacts of cosmic rays bombarding the Earth.
The Earth’s magnetic field lines deflect a large proportion of primary cosmic rays away from the upper atmosphere. However, this shield does not fully cover the regions around the North and South Poles. During solar eruptions, particles from the Sun are responsible for the phenomenon of the aurora borealis in polar regions.
Radiation doses during air travel
Measurements carried out on various air routes representative of exposure to cosmic radiation. The average dose rate (dose received per hour) during a flight is indicated in millionths of a sievert per hour (µSv/h) in the circles. The total dose (shown in the blue boxes) is given in millisieverts (mSv). In the case of the Paris–New York round trip, the flight was on Concorde.
© IRSN
Ascending to higher altitudes reduces the thickness of the protective layers of air. People living in the Andes and Tibetans in the Himalayas who spend the entire year at altitudes of 3,000 or 4,000 metres are exposed to additional radiation, as are mountaineers, skiers and airline passengers, who travel to even higher altitudes but only for a few hours.
Airline crew members are exposed to increased doses of cosmic radiation because aircraft generally fly at altitudes of around 10,000 m. Given the different types of radiation involved, aircrew do not wear passive dosimeters.
The doses are calculated using a code that has been validated by the French Civil Aviation Authority (DGAC), ASNR and the CNRS in Meudon, which assesses solar eruptions.
This Sievert PN code can be used to perform the calculations.
2024 dosimetry report:
Among the 23,150 airline personnel monitored, all were considered occupationally exposed to ionising radiation. The maximum dose recorded was 2.73 mSv over 12 consecutive months.
To avoid disclosing location information, military personnel are monitored using passive dosimeters, with a correction factor subsequently applied. © ASNR
Exposure levels remain modest. A passenger on a London–New York flight at an altitude of 11,000 metres will receive a dose of 0.032 mSv (millisievert), equivalent to a panoramic dental X-ray. Another passenger travelling on a route over the North Pole from New York to Hong Kong will receive a dose approximately three times higher, because the protection provided by the atmosphere and the Earth’s magnetic field is about half as effective at polar latitudes as it is at the equator.
A frequent traveller on this route (who is not included in the regulatory system), or a crew member, would need to make five round trips to receive 1 mSv, equivalent to a pelvic X-ray. One millisievert is also the recommended average annual exposure limit for the general public established by the International Commission on Radiological Protection (ICRP) and corresponds to approximately 40% of the average annual dose from natural background radiation, although it should be noted that natural background radiation varies by considerably more than 1 mSv from one location to another.
An additional millisievert remains a low dose for which no risk has been conclusively demonstrated. It should be recalled that the annual dose limits for people working in the nuclear industry are 20 mSv in Europe and 50 mSv in the United States. Measures are implemented to ensure that people receive doses that are as low as reasonably achievable.
Among air travellers, pregnant women, aircrew and frequent flyers who use air travel as routinely as others use a car are the most exposed. Since May 2000, a European directive has required airlines to monitor the doses received by their crews and to inform them when their exposure exceeds 1 mSv.
Cancer prevalence among commercial airline crews
In 2018, a scientific study by McNeely et al. was published in the journal Environmental Health and is available in open access.
This study found an increased prevalence of cancer among airline flight attendants. Compared with the general population with a similar socioeconomic status, flight attendants had a higher prevalence of all the cancers examined, particularly breast cancer, melanoma and non-melanoma skin cancer, with increases in risk of up to fourfold. One possible reason (but not the only one!) is the effect of cosmic radiation. High-energy particles arriving from space and reaching the upper atmosphere generate secondary radiation that can penetrate aircraft walls at an altitude of approximately 10 km.