Radiation originating directly or indirectly from extraterrestrial sources. Cosmic radiation is part of natural radiation and its dose depends on the altitude above sea level. At sea level it amounts to 0.3 mSv per year and 3,000 m altitude about 1.2 mSv per year. In the case of air travel, passengers receive an additional dose of cosmic radiation; for a flight Frankfurt – New York – Frankfurt about 0.1 mSv. (See also ‘radiation exposure – cosmic’)