United States Nuclear Regulatory Commission - Protecting People and the Environment
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Background radiation

The natural radiation that is always present in the environment. It includes cosmic radiation which comes from the sun and stars, terrestrial radiation which comes from the Earth, and internal radiation which exists in all living things. The typical average individual exposure in the United States from natural background sources is about 300 millirems per year. For additional information, see Natural Background Sources and Doses in Our Daily Lives.

Page Last Reviewed/Updated Tuesday, October 28, 2014