Abstract: With CR-39 SSNTD, nearly 900 indoor radon concentration levels of 13 provincial administered cities in Jiangsu province were investigated. The results show that the highest level of indoor radon concentration in Jiangsu is 238 Bq/m³, the lowest level is 5 Bq/m³, the arithmetic mean value is 30 Bq/m³, the population weighted arithmetic average value is 29.7 Bq/m³, the geometric mean value is 28.2 Bq/m³, and the public annual average effective dose induced by indoor radon is 0.76 mSv. Through the analysis of correlation coefficients between indoor/outdoor radon concentration and ²²⁶Ra content in soil, it can be preliminary concluded that the main factor influencing the indoor radon concentration in Jiangsu province is the radon exhalation of geological construction foundation (soil and rock).

Key words: indoor radon, CR-39 SSNTD, effective dose