Indoor radon and thoron concentrations in some towns of central and South Serbia.

This study presents the results of indoor radon and thoron activity concentrations of some municipalities in central and south part of Serbia: Krusevac, Brus, Blace and Kursumlija. Measurements were carried out in 60 dwellings during the winter season. Passive discriminative radon-thoron detectors known as UFO detectors were used. The mean values of indoor radon and thoron concentrations were 82 Bq m(-3) and 42 Bq m(-3), respectively. Population-weighted mean values were 76 Bq m(-3) and 40 Bq m(-3), respectively. 26.7% of dwellings had radon concentration higher than 100 Bq m(-3) (one location had even more than 300 Bq m(-3)). There are no statistically significant correlations of indoor radon and thoron concentrations neither with the period of house construction, nor with the existence of a basement. The results of this study represent the first step of investigating radon and thoron levels in these parts of Serbia and therefore could be the basis for creating a radon map.