ABSTRACT
@#Abstract: Objective In order to understand the radon exposure level of homes in Chongqing, this survey was carried out on the indoor radon concentration in 38 districts and counties of Chongqing. Methods According to the population ratio of every 100 000 people, one monitoring site was arranged, and the number of parallel samples was 10% of the distribution sites. The monitoring sites covered 38 districts and counties in Chongqing. A total of 1 019 residential monitoring sites in 38 districts and counties in Chongqing were measured with radon accumulation detectors from July 2020 to June 2021. Results The five districts/counties in Chongqing having the highest average concentration of residential radon in the year were Xiushan County 78.8 Bq/m3, Qianjiang District 78.0 Bq/m3, Yubei District 73.9 Bq/m3, Youyang County 71.4 Bq/m3 and Shapingba District 69.8 Bq/m3. The five districts/counties with the lowest mean concentration of indoor radon were 37.6 Bq/m3 in Zhongxian County, 36.4 Bq/m3 in Changshou District, 33.7 Bq/m3 in Kaizhou District, 33.2 Bq/m3 in Liangping District and 27.3 Bq/m3 in Wushan County. The concentration levels of radon in four seasons were 46.0 Bq/m3, 53.4 Bq/m3, 45.1 Bq/m3 and 59.5 Bq/m3, respectively. The concentration of radon was higher in Summer and Winter, and lower in Spring and Autumn, and the difference of concentration among four seasons was statistically significant (P<0.001). The radon concentration of newly built buildings after 2017 was relatively high, up to 61.8 Bq /m3, but there was no statistical significance in radon concentration in different building ages (P>0.05). The concentration of radon in rooms of buildings with less than 10 floors was higher, up to 63.2 Bq /m3, and there were significant differences in radon concentration among rooms of different floors (P<0.05). The average annual radon concentration in houses in Chongqing was about (51.6±19.5) Bq/m3, and the average annual effective dose of inhaling radon and its progeny by house-related people was about (1.38±0.52) mSv. Conclusion The average annual radon concentration level of houses in Chongqing is within the standard limit value recommended by China, but the prevention and control of radon should be strengthened.