Gamma activity and geochemical features of building materials: estimation of gamma dose rate and indoor radon levels in Sicily

A high-purity germanium detector has been used to measure the abundance of radium (Ra), thorium (Th) and potassium (K) in building materials used in Sicilian dwellings. The measurements were performed to evaluate which material was suitable for the construction of an enclosure, which would have a low background emission. The materials examined in this work showed concentrations of 226Ra, 232Th and 40K dramatically variable depending on the lithologies, particularly in the case of blocks, sands and aggregates commonly used in building materials in Sicily. The results are discussed and a criterion is indicated to reduce the radiation dose to humans. Since radon inlet is a major health problem, all the radiometric data and the geochemical features have been used to determine the radon exhalation, which arises from the disintegration of 226Ra in soils and walls of houses. From our experimental data it can be seen out that one of the geochemical parameters, Total Alkali (TA), may be an appropriate index to select materials of low radiological risk.