中国における Passive 法による屋内・外ラドン濃度調査

抄録

Measurements of ²²²Rn in outdoor air and indoor air have been carried out every 2 months during about one year from Nov. 1988 using passive electrostatic integrating ²²²Rn monitor developed by Iida et al. 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 12.2Bq·m^-3, respectively. The high outdoor ²²²Rn levels at Beijing and Xi'an, situated in inland area, may be attributed to high frequency of the occurrence of inversions in winter. The low ²²²Rn levels at Nanjing and Shanghai and the high ²²²Rn levels at Fuzhou and Guiyang correspond to their geological conditions and the ²²⁶Ra concentrations in soil. The annual mean indoor ²²²Rn concentrations were about 2-3 fold of outdoor concentrations at every city. The average indoor ²²²Rn concentration in China was 29.2Bq·m^-3. The annual effective dose equivalent resulting from outdoor and indoor ²²²Rn concentrations amounts to about 0.72mSv·y^-1.