Modeling and measuring the indoor radon concentrations in high-rise buildings in Hong Kong

A newly constructed, uninhabited high-rise building has been measured for its indoor and outdoor radon concentrations at similar locations on each of the 18 floor levels. Grab sampling technique has been used so that many locations can be measured within short period of time to minimize the variations due to temperature, pressure and humidity. Air exchange rates inside rooms were obtained by tracer gas method. Standard concrete samples were manufactured in laboratory to simulate the concrete used in the construction of the high-rise building. The concrete samples were measured for their radon exhalation rates by calculating the initial growth rates of radon inside an airtight container. The air exchange rates have been found to increase with floor levels, whilst the indoor and outdoor radon concentrations decreased with floor levels. Using a model utilizing a simple mass balance equation, the indoor radon concentration inside a room on each of the 18 floor levels has been calculated and the results agreed very well with measurements.