Indoor radon, thoron and their progeny concentrations in high thoron rural Serbia environments

Following the recent published paper (Mishra R., Zunic Z.S. et al., 2014) with results from 43 houses of Sokobanja (Southern Serbia), the results from a new survey in those region are subject of this work. This paper deals with the variation of radon, thoron and their progeny concentrations in 40 houses, distributed over the 4 villages of Sokobanja community, Southern Serbia. Two different types of passive detectors were used: 1) discriminative radon-thoron detector for simultaneous radon and thoron gases measurements and 2) direct thoron and radon progeny sensors (DRPS/DTPS) for measuring radon and thoron progeny concentrations, expressed in terms of equilibrium equivalent concentrations (EERC and EETC). Detectors were deployed on the wall in one of the most occupied room in each house and exposed simultaneously for a period of one year (i.e. a single period of 12 months). The results of measured concentrations were in the following ranges: from 8 to 189 Bq/m3 for radon and 10 to 412 Bq/m3 for thoron concentrations; from 5 – 22 Bq/m3 and 0.13 - 3.37 Bq/m3 for EERC and EETC, respectively. The geometric means (GM) and geometric standard deviation (GSD) were found to be GM=43 Bq/m3 (GSD=2.11) for radon, GM=89 Bq/m3 (GSD=2.25) for thoron, GM=10.2 Bq/m3 (GSD=1.48) for EERC and GM=0.86 Bq/m3 (GSD=2.14) for EETC. The variations of thoron and EETC appear higher than those of radon and EERC. An analysis of the spatial variation of the measured concentrations is also reported. This work is part of a wider survey of radon, thoron and their progeny concentrations in indoor environments throughout the Balkan region, started in 2011 year