Nguyen Thuy Duong, Nguyen Anh Nguyet, Nguyen Van Huong, Jan Schimmelamann, Nguyen Dinh Thai, Arndt Schimmelmann

Main Article Content


This article presents results of radon (222Rn) and thoron (220Rn) concentrations in room air measured inside mud-built houses that are traditional dwellings on the Dong Van Karst Plateau. The measurements were conducted in December 2016 and July 2017, corresponding to “cold” and “warm” months, respectively, by using a portable RAD7 detector. Our results show that 222Rn and 220Rn concentrations were elevated during the “warm” month and the concentrations of 220Rn were always higher than the respective 222Rn values at the same measured locations during the two months. The relatively long half-life of 222Rn (3.83 days) causes efficient dispersion and loss from room air due to air ventilation. In contrast, the much shorter half-life of 220Rn (55.6 seconds) results in elevated radiation near mud surfaces prior to attenuation into room air further away from walls and floors. Average concentrations of 220Rn in room air during both “cold” and “warm” months are much higher than in normal outside air (~10 Bq m-3). The severely elevated concentrations of 220Rn in room air of mud-built homes are likely harmful to human occupants, especially to those sleeping near mud-walls.

Keywords: Radiation, radon gas, 222Rn, 220Rn, temperature, air ventilation.




[1] J. Gunn, Radon in caves, in: J. Gunn (Ed.), Encyclopedia of Caves and Karst Science, Fitzroy Dearborn, Taylor & Francis Books, Inc., London, UK, 2003, pp. 617-619.
[2] The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), UNSCEAR 2008 Report to the General Assembly, with Scientific Annexes, in: Sources and Effects of Ionizing Radiation, vol. I, United Nations, New York, 2010.
[3] World Human Organization WHO, 2010. WHO Guidelines for Indoor Air Quality: Selected Pollutants. Geneva: World Health Organization, ISBN-13: 978-92-890-0213-4.
[4] V. Balek, I.N. Beckman, Theory of emanation thermal analysis XII - Modelling of radon diffusion release from disordered solids on heating, J Therm Anal Calorim 82 (2005) 755-759. 10.1007/s10973-005-0960-7.
[5] A. Sakoda, Y. Ishimori, K. Yamaoka, A comprehensive review of radon emanation measurements for mineral, rock, soil, mill tailing and fly ash, Appl Radiat Isotopes 69 (2011) 1422-1435. https://doi. org/ 10.1016/j.apradiso.2011.06.009.
[6] M. Schubert, A. Musolff, H. Weiss, Influences of meteorological parameters on indoor radon concentrations (222Rn) excluding the effects of forced ventilation and radon exhalation from soil and building materials, J Environ Radioactiv 192 (2018) 81-85. 2018.06.011.
[7] B. Shang, B. Chen, Y. Gao, Y.W. Wang, H.X. Cui, Z. Li, Thoron levels in traditional Chinese residential dwellings, Radiat Environ Biophys 44(3) (2005) 193–199. 411-005-0020-5.
[8] S. Gierl, O. Meisenberg, M. Wielunski, J. Tschiersch, An unattended device for high-voltage sampling of radon and thoron progeny, Rev Sci Instrum 85 (2014).
[9] D. Nguyễn-Thùy, H. Nguyễn-Văn, J. Schimmelmann, T.A.N. Nguyễn, K. Doiron, A. Schimmelmann, 220Rn (Thoron) Geohazard in Room air of Earthen Dwellings in Vietnam, Geofluids, article ID 7202616, 11 pages, (2019). /2019/7202616.
[10] Ha Giang Statistics Office (GSO), Mean air temperature at Ha Giang station, in: Statistical Yearbook of Ha Giang 2018, Statistical Publishing House, Ha Giang, 2019, p. 24 (in Vietnamese).
[11] DURRIDGE Company, 2017. RAD7 Electronic Radon detector - user manual. Durridge, Radon Capture & Analytics, Durridge Company Inc.
[12] The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), in: Sources, vol. I. United Nations, New York, 2000.
[13] M. Faheem, Matiullah, Radon exhalation and its dependence on moisture content from samples of soil and building materials, Radiat Meas 43(8) (2008) 1458–1462. eas.2008.02.023.
[14] W. Zhuo, T. Lida, S. Morizumi, Simulation of the concentration levels and distributions of indoor radon and thoron, Rad Prot Dosim 93 (2001) 357-368. 06448.