A pilot study for dose evaluation in high-level natural radiation areas of Yangjiang, China.

A pilot study to measure ambient gamma dose rate and radon and thoron progeny concentrations was made for eight dwellings selected in Yangjiang, China. Indoor and outdoor ambient gamma dose rates were 110-370 and 100-220 nGy h, respectively. Doses received from indoor terrestrial radiation were estimated to be 0.6-1.8 mSv year. Radon, thoron and thoron progeny concentrations were 19-98, 18-1120 and 0.4-10.3 Bq m, respectively. This pilot study showed that the position of passive-type monitors to be placed and the deployment period should be carefully determined for estimating reliable annual average concentrations. [ABSTRACT FROM AUTHOR]