A national survey on radon concentration in underground inspection rooms and in buildings of a telephone company: methods and first results

A national survey has been carried out to measure radon concentration in a large sample of Telecom-Italia small underground inspection rooms, which form a particularly dense net in urban areas. Measuring radon in such underground places is interesting both for a possible contribution to radon mapping activities and to evaluate workers exposures. Radon concentration was also measured in Telecom buildings (i.e. buildings housing plant equipment, including telephone switches, often also offices, etc.) close and partially connected to the selected inspection rooms. The methodology and the first results of the survey related to the first year of measurements, for a total of 1438 inspection rooms and 1414 Telecom buildings, are reported. Radon concentration was measured with passive devices containing CR-39 detectors for about 12 consecutive months, in order to average seasonal variations. In underground inspection rooms, measured radon concentration reached values up to about 44,000 Bq/m3, with a regional median ranging from about 90 Bq/m3 up to about 1600 Bq/m3. In Telecom buildings, the regional median concentration ranged from 13 Bq/m3 to 174 Bq/m3. These results show that radon concentration in underground inspection rooms can reach very high values, whereas medians in monitored buildings are generally lower than those measured in dwellings in a representative national survey.