Key ideas1 of 3
Radiation is present around us
Background radiation is the ionising radiation continually present in the environment. Natural sources include radioactive substances in rocks and soil, radon gas, radioactive material inside living organisms, and cosmic radiation from space. Artificial sources include medical procedures and fallout from nuclear-weapons testing and nuclear accidents. A detector can therefore register counts even when no laboratory source has been placed beside it. Background is not automatically evidence of contamination from a recent accident.
