Background Natural Radiation
Background radiation, i.e., ionizing radiation present in the environment may be from natural origin or artificial/man-made sources. Natural background radiation sources are cosmic rays and terrestrial sources, natural radioactive material such as radon from ground, building walls and floors, and traces of naturally occurring radioactive material in food and drinks. Artificial or man-made origin includes radioactive fallout from nuclear weapons test and major nuclear accidents, medical diagnostic and therapeutic use of ionizing radiation, X-ray machines, particle accelerators, consumer products and transport of radioactive materials.
Worldwide average of effective dose from background natural radiation is about 2.4 mSv/year (2400 µSv/year). In Kerala coast this is about 12.5 mSv/year. In northern Iran, this value is about 260 mSv/year.
