Background Radiation
Radiation is everywhere, it is inescapable. Because radiation is everywhere, we have to be able to distinguish between normal radiation occurrences versus abnormal occurrences.
Background radiation is the normal dose of radiation an individual is subject to in any given area. Background radiation is not necessarily naturally occurring radiation. Background radiation sources are usually due to elevation, rock formations, close proximity to nuclear facilities.
Non-background radiation is anything above the "normal radiation" in a given area. This also does not have to be just man made.