The number of counts recorded by a radiation detector from background radiation. The term background radiation refers to the natural ionizing radiation on the Earth. Ionizing radiation refers to all radiations, waves, and particles that are energetic enough to remove electrons from stable atoms; they are stronger than infrared radiation, radio waves, or visible light, which cannot separate electrons from stable atoms. Radiation strong enough to cause ionization of atoms is measured in electrical units which range from 32 electronvolts up to millions of electronvolts.