A territory-wide survey of indoor gamma dose rate and its relation to indoor radon level in Hong Kong

A territory-wide survey of indoor radon level and indoor gamma dose rate was conducted in 1993. This paper reports the result of the indoor gamma dose rates and assesses the relationship between gamma dose rate and radon concentration in various types of buildings in Hong Kong. The TLDs and passive radon detectors were exposed simultaneously for about six months. The overall arithmetic mean gamma dose rate is 0.22 mu Gy hr(-1) with a standard deviation of 0.04 mu Gy hr(-1). The modal gamma dose rate in high radon level rooms (>100 Bq m(-3)) is 0.28 mu Gy hr(-1) and in low radon level rooms (<100 Bq m(-3)) is 0.22 mu Gy hr(-1). The correlation between gamma dose rate and radon level is ventilation dependent and the regression coefficient ranges from 1.5 x 10(-4) to 1.8 x 10(-4) mu Gy hr(-1) per Bq m(-3). Other factors that affect the indoor gamma dose rate and its relation to radon level are also discussed.