Background radiation, people and the environment

All living organisms are exposed to ionizing radiation comprising cosmic rays coming from outer space, terrestrial nuclides occurring in the earth’s crust, building materials, air, water and foods and in the human body itself. The exposures are constant and uniform for all individuals everywhere including the dose from ingestion of 40K in food. Cosmic rays are, more intense at higher altitudes, and the levels of uranium and thorium in soils are elevated in localized areas. Exposures also vary as a result of human activities and practices. In particular, building materials of houses and the design and ventilation systems strongly influences the indoor levels of the radioactive gas radon and its decay products, which contributes the doses through inhalation. Component of the sources of exposures to Indian population has been assessed based on the data generated. Total contribution from the natural sources to the Indian population works out to 2.3 mSv/y as against the global value of 2.4 mSv/y. Estimated modified source including mining of heavy metals, coal fired power plants, mining of phosphate rocks and its use as fertilizers, production of natural gas, gas mantles and luminescent dial and air travel contribution to the background radiation to the Indian population works out to be 1.2 x 10-3 mSv/y atmospheric weapon tests contributes about 0.045 mSv/y, medical exposure contributes about 0.048 mSv/y and exposure due to nuclear power production contributes about 5.0 x 10-5 mSv/y to the background radiation. Brief review and comparison of the dose rates arising from natural and man made sources to the Indian population is given. Iran. J. Radiat. Res., 2011 9(2): 63-76