ABSTRACT
This chapter describes natural sources of radiation exposure and discusses artificial sources of radiation exposure. It explains the main radionuclides that contribute to external and internal terrestrial radiation exposure and provides some common consumer products that contain radioactive material. The chapter identifies the artificial source of radiation that accounts for the greatest dose to the average person in the United States. It presents common occupational sources of radiation exposure and explores contrast occupational radiation exposures due to NORM with those from other sources. There are many areas of the world where radon exposures are high. Such exposures seem to be mainly related to radon and radium dissolved in water supplies. Cosmic radiation was discovered while experimenters were trying to find ways to reduce background radiation levels. The origins of cosmic radiation can be categorized as either solar or galactic. Galactic radiation is composed mostly of charged particles and gamma rays and comes from outside the solar system.
