The background noise designs the activity of the different radionuclides present in the environment, outside any current human activity (nuclear industry, other industies, discharges from hospitals, ...). This background noise results partially from natural sources, and partially from the persistence of old contributions of artificial radionuclides, which concerned the entire territory;  these include fallout from atmospheric nuclear weapons and fallout of Chernobyl accident. This background noise contributes to the radiological exposures to which the population is subject.