RADIATION HAZARDS OF AIR TRAVEL

Modern commercial aircrafts operate at altitudes varying from 8 to 16 km from the surface of the earth. Cosmic radiation coming from space is a mixture of many different types of radiation, such as protons, alpha particles, electrons and other high energy particles. The radiation is affected by the earth’s magnetic field and while entering the atmosphere, its intensity reduces due to interaction with the environment. At ground level, the cosmic radiation is mainly consists of muons, neutrons, electrons, positrons and photons. Thus, as the altitude decreases, the cosmic radiation dose also reduces. For example, the dose rate at sea level, at the top of Himalayas, and at 15 km height can be 0.03 micro Sv/h, 1 microSv/h and 10 micro Sv/h. European Commission working group ((EURADOS WG-5) reported typical per flight exposures of 67 microSv and 47.8 microSv to the aircraft crew flying from London to Tokyo and Montreal to London respectively.

This brings into focus the radiation protection aspects of airline crew and of frequently flying airline passengers. The International Commission on Radiological Protection (ICRP) recommends that the airline crew should be treated as radiation workers and for normal flying hours put up by the crew, the expected average annual dose is reported to be of the order of about 2.5 milliSv. This can be compared with the 20 milliSv, the annual average occupational dose limit recommended by the ICRP for all radiation workers. Annual dose limit recommeneded for the members of the public from man-made radiation sources is 1 milliSv.

The number of passengers flying is growing fast, rather exponentially in some countries and if all the doses of the passengers and the crew are added up (collective dose), the statistically estimated health consequences due to the radiation exposure of the group of population is of concern from radiation protection point of view. Now, compares this risk of the health consequences with the risk of potential airline accidents, the radiation exposure risk will work out to be higher!

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