background radiation

low-level radiation suffusing the surface of the earth

Background radiation is the ionizing radiation emitted from a variety of natural and artificial radiation sources. Primary contributions come from:Sources in the Earth. These include sources in our food and water, which are incorporated in our body, and in building materials and other products that incorporate those radioactive sources; Sources from space, in the form of cosmic rays; Sources in the atmosphere. One significant contribution comes from the radon gas that is released from the Earth's crust and subsequently decays into radioactive atoms that become attached to airborne dust and particulates. Another contribution arises from the radioactive atoms produced in the bombardment of atoms in the upper atmosphere by high-energy cosmic rays.
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Back·ground radiation n. Relatively constant low-level radiation from environmental sources such as building materials, cosmic rays, and ingested [more]Background radiation - Community and Resources

Noun
1. radiation coming from sources other than those being observed
(hypernym) background, background signal

Nuclear (or ionizing) radiations arising from within the body and from the surrounding to which individuals are always exposed. 1/2/73

Irradiation qui émane du milieu ambiant, ou du corps humain lui-même, et à laquelle tous les individus se trouvent exposés en permanence. 1/2/73