Led by Dr. Matthias Meier
The recommendation of the International Commission on Radiological Protection (ICRP) in 1990 to classify aircrew as "radiation workers" entailed a revision of the European Union's Basic Safety Standards. The council directive 96/29/EURATOM of May 13, 1996 obliges the member states to "make arrangements for undertakings operating aircraft to take into account of exposure to cosmic radiation of air crew who are liable to be subject to exposure to more than 1 mSv per year". This stimulated new measurements at aviation altitudes and a number of epidemiological studies all over the world.
Beside some very rare solar particle events, the galactic cosmic radiation which impinges continuously on the earth brings about the corresponding radiation exposure. Through interactions with the atoms of the atmosphere’s components secondary particles (eg. neutrons, electrons, protons, muons and pions) are produced. Since lower energy particles are deflected by the earth magnetic field there is a strong latitude dependence of both the primary and secondary radiation field the intensities of which decrease towards lower latitudes. Solar cycle modulation effects of the primary particles are also observed and are most striking at higher latitudes (approx. factor of two). Measurements of the radiation exposure range from 2 - 10 µSv/h at altitudes between 11 and 13 km depending on latitude and time in the solar cycle. Exposure levels are therefore by up to a factor of 100 higher than at sea level.
Since the radiation field at aviation altitudes is very complex, several measurement campaigns with a variety of radiation detectors were performed from which good knowledge on the radiation exposure has been achieved. Computer programs for dose determination have been developed and compared with these measurements showing an excellent agreement. Therefore the radiation exposure of flight crew can be determined using the developed programs. Future measurements will be necessary to verify the calculations due to modulation of the radiation field at aviation altitudes by the solar cycle.
Cancer incidence and mortality studies as well as investigations of chromosomal changes have already been performed by several institutions worldwide. None of these studies could show with sufficient statistical significance any increase in detrimental health effects due to radiation exposure of aircrew included in such studies so far.