Indoor thoron and radon concentrations in zhuhai, china

Abstract

A field survey of 54 dwellings and 21 points outdoors around Zhuhai area was carried out using a newly developed integrating monitor in the spring of 2001 for a preliminary exposure assessment on 222Rn and 220Rn progeny, focusing especially on 220Rn progeny levels and its contribution to the general public. The flux rates of 222Rn and 220Rn from ground soil and soil nuclide contents were measured simultaneously. The average EECRn and EECTn were 52:9±39:1 Bq-m-3 and 4:0±2:3 Bq-m-3 for dwellings and 7:5±3:6 Bq-m-3 and 0:6±0:2Bq-m−3 for outdoor air, respectively. Rather high 220Rn flux rates from ground surface were measured, the mean value was 2;645:1 + 1;667:6 mBq-m−2-s1. The estimated radiation exposures from the exhalation of 222Rn and 220Rn progeny were 3.3 mSv-a−1 and 1.1 mSv-a−1, respectively. The exposure from 220 Rn progeny was some 1/3 that of 222 Rn progeny, and ought not to be ignored from the viewpoint of radiation protection in Zhuhai area. © 2002 Taylor & Francis Group, Ltd.