Indoor radon measurements in Adelaide, South Australia

In 1986 a study of radon levels in homes in Melbourne was made, using activated charcoal to adsorb the gas from indoor air. Cups containing 25g of activated charcoal were exposed for periods of nominally 7 days. The cups were sealed and the accumulated activity was measured by gamma counting. Cup activity was related to ambient radon concentration by calibrations done in the Australian Radiation Laboratory's radon reference chamber. This work was continued in Adelaide, South Australia (S.A.) between July and November 1986 using the same methods. Cups were exposed in their homes by 213 volunteers from the staff of the S.A. Institute of Technology and the S.A. Health Commission. The median concentration of radon in air was 10 Bq/m3, with 90% of values below 35 Bq/m3, and 100% below 75 Bq/m3. The lower bound of the distribution is poorly defined because of inadequate counting statistics. 4 refs., 6 figs