A new subnationwide survey of outdoor and indoor 222Rn concentrations in China

Surveys of outdoor and indoor 222Rn concentrations in China were made with two-month integrating times from November 1988 to January 1990, and from February 1991 to March 1993. In the first survey, the annual mean outdoor 222Rn concentrations at Beijing, Xi'an, Nanjing, Shanghai, Fuzhou, and Guiyang were 8.0, 11.2, 6.4, 4.8, 9.5, and 12.2 Bq m−3, respectively. The results of the second survey at Changchun, Huhehaote, Shanghai, Wuhan, Fuzhou, and Guiyang were 10.1, 8.6, 4.3, 14.6, 10.2, and 11.8 Bq m−3, respectively. The annual mean indoor 222Rn concentration was 21.8 Bq m−3 in typical buildings constructed with concrete and brick. The highest indoor 222Rn concentration of 38.1 Bq m−3 was observed at Guiyang, and the lowest concentration of 11.3 Bq m−3 was at Huhehaote. The annual effective dose equivalent resulting from outdoor and indoor 222Rn and its daughter products amounts to about 0.67 mSv a−1 in China.