Radon levels in underground workplaces - results of a nationwide survey in Italy

In Italy an extensive survey has been carried out with the aim to evaluate annual average radon concentration in underground workplaces. The survey covered 933 underground rooms located in 311 bank workplaces spread throughout in all Italian regions; at this scope the sampling was stratified random in order to be representative on national scale. The annual radon concentration was estimated by using passive radon dosemeters (NRPB/SSI type holder and CR-39 as detector): the devices were exposed for a period of about 3 months and 4 cycles were performed to cover a solar year. The radon levels in underground workplaces ranged from 27 to 4851 Bq/m(3) with an overall mean value of 153 Bq/m(3). As expected, radon distribution is not uniform throughout Italy: in several regions high radon annual averages have been found, confirming previous surveys. The analysis of data shows a high variability among regions and intra-region but low spread among rooms belonging to the same workplace. bout 5% of underground workplaces displayed radon concentration exceeding 400 Bq/m(3), and the 4.4% exceeds 500 Bq/m(3), the national action level for the exposure to natural radioactivity in workplaces. (C) 2011 Elsevier Ltd. All rights reserved.