The effect of fall-out deposition on indoor gamma radiation levels in single-family dwellings

The deposition of atmospheric fall-out on the surfaces of buildings and their immediate vicinity results in a modification of the baseline indoor gamma dose rate due to the natural radiation environment (NRE). Based on 430 gamma dose rate (Dγ) measurements indoors this modification was studied at buildings comprised of single-family dwellings and farmhouses in Salzburg. The results indicate a significant increase of Dγ in the attic area and adjacent rooms over the NRE value. In farmhouses Dγ in the work and storage area of contaminated hay can be increased up to 550% over the NRE value. Also for shells under construction fall-out deposition Dγ levels have been found to be increased. (author)