Calculate cosmic radiation exposure during air travel. Understand your radiation dose from flying at high altitudes.
Last updated: March 2026
NYC to London ≈ 7-8 hrs, LA to Tokyo ≈ 11-12 hrs
Commercial flights typically cruise at 30,000-42,000 ft
Cosmic radiation is high-energy particles from outer space that constantly bombard Earth. At ground level, Earth's atmosphere and magnetic field provide substantial shielding. However, at cruising altitude (30,000-42,000 feet), aircraft fly above much of this protective atmosphere, exposing passengers and crew to increased cosmic radiation.
The radiation dose from flying comes primarily from galactic cosmic rays—protons and atomic nuclei accelerated to nearly the speed of light by supernovae and other cosmic events. Solar radiation also contributes, with doses increasing during solar particle events (solar storms).
Radiation exposure is measured in millisieverts (mSv). A typical transatlantic flight delivers about 0.03-0.05 mSv of radiation—roughly equivalent to 1.5-2.5 chest X-rays. While this is a small amount, it's important for frequent flyers and flight crew to track cumulative annual exposure.
*Base rate of 0.003 mSv/hr at 35,000 ft is a simplified estimate. Actual exposure varies with altitude, latitude, route, and solar activity.
Calculate annual exposure for a frequent business traveler:
This annual dose is equivalent to about 14 chest X-rays and represents 28.8% of the 1 mSv/year public exposure limit. For context, average background radiation from natural sources is ~2.4 mSv/year. Flight crew who fly 900+ hours annually can receive 3-6 mSv/year.
For occasional travelers, the dose is negligible. Even frequent flyers receive far less than occupational limits (20 mSv/year). Flight crew are monitored and classified as radiation workers in some jurisdictions. The risk is cumulative.
Occasional flights pose minimal risk. However, pregnant women who fly frequently (especially flight attendants) should consult their doctor. Guidelines suggest limiting exposure to under 1 mSv during pregnancy.
Very little. Aircraft aluminum is too thin to block cosmic rays effectively. Some carbon composite materials in newer aircraft may offer slightly better shielding, but the difference is marginal.
Yes. Polar routes (e.g., NYC to Hong Kong over the North Pole) receive roughly double the radiation of equatorial routes due to Earth's magnetic field concentrating cosmic rays at the poles.
Chest X-ray: ~0.02 mSv. An 8-hour transatlantic flight: ~0.03-0.05 mSv. A CT scan: 7-10 mSv. However, flight radiation is whole-body exposure, while medical imaging is typically localized.
Studies show slightly elevated rates of certain cancers in flight crew, but causation is complex. Other factors include disrupted circadian rhythms, lifestyle, and occupational exposures. Radiation is one contributing factor.
Not significantly. You can't shield yourself from cosmic rays with materials available on aircraft. The only way to reduce exposure is to fly less, choose lower altitude flights, or avoid polar routes.
For the general public: 1 mSv/year above background (regulatory limit in many countries). For radiation workers: 20 mSv/year averaged over 5 years, with no more than 50 mSv in any single year.
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