Man receives radiation doses from a variety of sources. Background radiation from terrestrial sources, cosmic rays, and the internal deposition of naturally occurring radioactive materials amounts to about 94 mrem/yr at sea level and varies widely with location and elevation. Medical services are estimated to contribute an average of 75 mrem/yr currently. Global fallout from previous weapons tests contribute about 4 mrem/yr. For 1970 the average annual dose from the U.S. nuclear power industry was about 0.003 mrem. Extensive studies have shown that in the year 2000 the average annual dose from nuclear power generation may be about 0.4 mrem/yr. For the average U.S. citizen, the largest annual radiation dose arises from naturally occurring background. For the year 1970, the radiation dose from the U.S. nuclear power industry was about 0.003% of that received from unavoidable natural background radiation. For the year 2000, the radiation dose from the U.S. nuclear power industry is predicted to be about 0.5% of that received from unavoidable natural background radiation.