Modelling exposure to naturally occurring radionuclides in building materials

Abstract

In this paper, model calculations were used to predict the external γ dose rate and indoor 222Rn concentration inside a typical dwelling found in Hong Kong. The radionuclide contents in the building materials were taken from previous measurements. The equivalent γ dose rate inside the room built of concrete was computed to be about 0.95 mSv.y-1 which was in good agreement with a previously measured population-weighted mean equivalent γ dose rate of 0.93 mSv.y-1. This value was a few times higher than the reported values in European countries. Addition of fly ash to the concrete has only a slight effect in the γ dose rate. The computed indoor 222Rn concentration also agreed with the arithmetic mean of 42 Bq.m-3 obtained in a previous survey. The seasonal variation of indoor 222Rn concentration was predicted by considering the change in ventilation and meteorological conditions. Based on the predicted values, the excess lung cancer cases attributable to indoor 222Rn was estimated to be 201 and 67 for men and women respectively.