The variation of radon exhalation rates from building surfaces of different ages

Standardized activated charcoal canisters (according to the U.S. EPA) have been used to collect radon exhaled from concrete surfaces covered with thin plaster (categorically different from thick plaster) of 32 buildings of different ages (0.5-31 y) in Hong Kong. Concrete surfaces covered with thin plaster is the commonest wall configuration in Hong Kong. The canisters are analyzed using gamma spectroscopy to obtain the radon exhalation rates. The results show that the radon exhalation rate decreases with the building age.