Abstract. Radon ( 222 Rn) is the most important cause of exposure to mankind due to natural radioactivity. Radon exhalation depends not only on the 226 Ra concentration in the material, but also on other factors such as mineralogy of the region, size and density of grains and porosity of the material. As building materials are one of the major sources of environmental radon, the radiological implications of the use of materials with great content of uranium must be always assessed. In this work, radon exhalation from several undamaged granitic building materials used as ornamental rocks or coating tiles is determined using the "sealed-can technique" and CR-39 solid state nuclear track detectors (SSNTD). Preliminary results for radon concentrations showed values of the same order that literature values, in a range from 99 Bq.m −3 to 1100 Bq m −3 . Further, the methodology will be validated with standard sources of 222 Rn.

Natural radioactivity concentrations in commercially-used granites from Paraná state, Brazil, were measured in order to estimate the potential radiological hazard to mankind due to granite as an ornamental building material through the 226 Ra, 232 Th and 40 K activities concentrations measured in several samples by high-resolution gamma-ray spectroscopy. Preliminary results, without considering samples selfattenuation, show activities concentrations varying from 4 ± 1 Bq kg −1 to 79 ± 3 Bq kg −1 for 226 Ra, 7 ± 1 Bq kg −1 to 142 ± 6 Bq kg −1 for 232 Th and 214 ± 14 Bq kg −1 to 1626 ± 77 Bq kg −1 for 40 K. All results are within the range of literature values for similar rocks. Further, the annual effective dose, the radium equivalent activity and the external and internal hazard indexes will be assessed.

The radiation exposure through drinking-water comprises: naturally occurring radioactive species radium-226/228 and a few others. The classical approach to radioactivity measurements in drinking water consists of evaporating a known volume of water and measure the activity of the residue in a glass flow proportional counter; an attractive alternative to classical methods is the ultra-low level liquid scintillation counting coupled to alpha–beta discrimination. The main aim of this work is to compare these two methodologies, considering an identical initial step of pre-concentration, in terms of: principles involved in the measurement (efficiency, measuring time, background radiation); minimal detectable activity; time to perform the analysis.