Exposure of crew to cosmic radiation and safety measures for aircrew have been a topical issue for many years but are becoming increasingly important for airlines, pilot and flight attendants unions, international organisations and various government bodies.
A landmark ruling against an airline in 2023 [1] decided that there was a causal link between a long serving former flight attendant's prolonged period of exposure to cosmic radiation during the course of his employment and his death due to stomach cancer, notwithstanding that the airline had taken reasonable steps in restricting their cabin crew exposure to below legally required limits. The crew member had flown at high altitude polar routes for a period of 25 years. The Labour panel rejected the airlines defence, concluding that a "considerable" correlation is recognized when considering the victim's accumulated radiation exposure, which could be higher than measured, and other disadvantageous work environments involving long-haul flight schedules. This raises the prospect of potential liability for airlines in similar circumstances.
Cosmic radiation is a form of ionising radiation and is a known carcinogen (or cancer causing) risk. Various studies have found a correlation between acute overexposure to cosmic radiation and the risk of certain types of cancers although there are usually other factors involved which contribute. The ICRP [2] has stated that aircrew members are occupationally exposed to higher levels of cosmic radiation than the general public.
All flights involve exposure to some form of cosmic radiation, however exposure increases with altitude and latitude as well as flight duration. So how much cosmic radiation are aircrew exposed to and what are the recommended limits? According to IAEA data, an aircrew's effective dose is less than 1 milli-Sievert (mSv) in a year if the routes flown do not exceed an altitude of around 9,000 metres but for those who fly long haul polar routes the typical radiation doses are 6 mSv per year.
Some jurisdictions have mandatory laws in place to regulate protection of aircrew members from cosmic radiation exposure. Many regulatory authorities require monitoring and recording of radiation for higher altitude flights and there are implications for compliance with local health and safety legislation, such as requiring a risk assessment and taking reasonably practical steps to minimise and control these risk.