Led by Dr. Matthias Meier
Life on Earth is very effectively protected against extra-terrestrial radiation by the atmosphere and the magnetic field. The effect of this natural protection diminishes with increasing height above ground and leads to accordingly increased exposures at aviation altitudes, which are primarily caused by the galactic cosmic radiation that impinges continuously on the Earth. Secondary particles (e.g. neutrons, electrons, protons, pions and muons) are produced through interactions with the atoms of the atmosphere’s constituents. Since low-energy particles are deflected by the Earth’s magnetic field, there is a strong latitude dependence of both the primary and secondary radiation field, the intensities of which decrease towards lower latitudes.
Occupational radiation protection of aircrew has been legally regulated in Germany since 2001. In practice, the corresponding exposures are assessed by model calculations along the flight route through the very complex radiation field within the Earth’s atmosphere. The German Aerospace Center has performed measuring flights in cooperation with several German airlines for quality control of model calculations and the investigation of the variation of the radiation exposure in dependence on solar activity since 2004. These measurements of the radiation exposure have shown dose rates from approximately 2 to 10 µSv/h at altitudes between 10 and 13 km depending on latitude and solar activity within the solar cycle and have demonstrated an excellent agreement with corresponding model calculations so far.
Space weather events associated with the emission of high-energy particles can in principle lead to significantly increased short-term exposures at aviation altitudes, especially in the polar region. However, this only occurs extremely rarely, and usually most of these space weather events even lead to a reduction in radiation exposure at cruising altitudes due to the magnetic field generated by these particles. An accurate statement about the effect of a space weather event on the radiation exposure in individual cases is only possible with a comprehensive analysis based on the available information. The German Aerospace Center is working on post event analysis, the development of real time space weather warnings and operational procedures for flight operations to keep the radiation exposure of aircrew and passengers as low as reasonably achievable (you will find further information on: Solar activity reduces radiation exposure in the air).