Radon exposure to tour guides in Australian show caves

Abstract A 12-month study of 222 Rn levels in Australian show caves was commenced in June 1994. This paper reports preliminary seasonal results in the winter and spring exposure periods. Measurements using passive radon monitors were carried out at over 270 sites, covering 57 cave systems at 23 locations around Australia. The mean and standard deviation (SD) of the 222 Rn levels for all Australian show caves was 500 ± 40 and 795 ± 50 Bq m −3 , for winter and spring, respectively. The highest value measured was 6330 Bq m −3 . Five of the cave systems had six-monthly 222 Rn levels exceeding the proposed intervention level of 1000 Bq m −3 . Increasing the ventilation in these caves is not possible, and it is likely that some form of radiation monitoring, either personal or area, will be required for tour guides working in these cave systems.