Indoor radon levels in Greek schools.

Radon and gamma dose rate measurements were performed in 512 schools in 8 of the 13 regions of Greece. The distribution of radon concentration was well described by a lognormal distribution. Most (86%) of the radon concentrations were between 60 and 250 Bq m(-3) with a most probable value of 135 Bq m(-3). The arithmetic and geometric means of the radon concentration are 149 Bq m(-3) and 126 Bq m(-3) respectively. The maximum measured radon gas concentration was 958 Bq m(-3). As expected, no correlation between radon gas concentration and indoor gamma dose rate was observed. However, if only mean values for each region are considered, a linear correlation between radon gas concentration and gamma dose rate is apparent. Despite the fact that the results of radon concentration in schools cannot be applied directly for the estimation of radon concentration in homes, the results of the present survey indicate that it is desirable to perform an extended survey of indoor radon in homes for at least one region in Northern Greece.