Population exposure due to natural radiation in an urban district of the Federal Republic of Germany

In order to estimate the reference risk to a typical group of the public, personal doses and indoor exposures due to natural radiation and indoor radon concentrations have been determined in the urban district of Nuernberg-Fuerth-Erlangen, FRG (about 690,000 inhabitants). Shielded CaF2-dosemeters were distributed to 926 individuals, selected according to random population sample, together with radon diffusion chambers to some of their respective dwellings for an exposure time of 3 to 4 months. The frequency distributions of the exposure rate in dwellings, of the personal dose rates and of the radon activity concentrations in dwellings have been obtained. From personal dose rates and radon activity concentrations, the frequency distributions of the annual effective dose equivalents were estimated. Mean values of 0.46 mSv due to terrestrial radiation (range: 0.07 to 1.18 mSv) and 1.01 mSv due to indoor radon inhalation (range: 0.15 to 3.75 mSv) were found. (author)