Detailed measurements of indoor radon levels in five residential premises and the effect of ventilation

Detailed radon measurements and ventilation testing were carried out in five residential premises in Hong Kong. Continuous radon detectors were located in the bedrooms of each site and corresponding CO₂ decay tests were conducted to estimate the ventilation rate. Four air-conditioning operation modes were used in the measurements. Data obtained from the measurements were used to verify the validity of a simple mass balance model. In this paper, factors including the elevation of the building, geographical composition of the area, diurnal variation of the radon level and influence of the ventilation rate on indoor radon level are also discussed