Abstract
A survey on radon (222Rn), thoron (220Rn) and its decay products (220RnD) was conducted in Chinese traditional residential dwellings constructed with loam bricks or soil wall. The activity concentrations in 164 dwellings under investigation were 72.4±59.2 (arithmetic mean, AM) and 57.5±2.0 Bq m−3 (geometric mean, GM) for 222Rn, and 318±368 and 162±3.7 Bq m−3 for 220Rn, respectively. For 220RnD, 67 dwellings were studied. The AM of the 220RnD equilibrium equivalent concentration was 3.8±3.3 Bq m−3 with a maximum value of 15.8 Bq m−3. On the basis of these results, the average annual effective doses to the local residents due to radon and thoron exposure were 1.44–4.62 mSv. Thoron contributes 12.9–56.6% to the total doses. Preliminary results show that there is a relation between 220RnD in air and 232Th in soil. The correlation factors of outdoor and indoor were 0.88 and 0.40. The 232Th activity content of Chinese soil is estimated to be about two times the world average. The traditional residential dwellings with soil construction are still common in China. Further investigations on the 220Rn level in these dwelling with the aim of dose reduction are proposed.
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Acknowledgments
We would like to thank Dr. J. Tschiersch, GSF-National Center for Environment and Health, Germany, for his useful discussions and suggestions. We also want to thank Ms. M. Müsch, GSF, Dr. Li Jing, Peking Union Medical College, and Ms. Dong Xiaoyan, Institute for Environment and Hygiene, China, for the field measurement of the thoron- decay products and the radon and thoron exhalation rate. This work is part of the study on health effects from radon exposure in residences, supported by the Social Service Study Foundation from the Ministry of Science, no. 2001DIA 10001.
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Shang, B., Chen, B., Gao, Y. et al. Thoron levels in traditional Chinese residential dwellings. Radiat Environ Biophys 44, 193–199 (2005). https://doi.org/10.1007/s00411-005-0020-5
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DOI: https://doi.org/10.1007/s00411-005-0020-5