Radon, gamma-ray exposure and natural radionuclides

Abstract Measurements were conducted to determine residential radon exposure levels in provinces with high lung cancer incidence in three different regions of Thailand. The measurements revealed that the average indoor radon levels were 20.0, 24.4, and 13.1 Bq m−3, and that the average gamma dose rates were 145, 164, and 54 nSv h−1 in Chiangmai, Songkhla and Khonkaen provinces, respectively. The spectroscopic analysis of soil samples collected from the three provinces showed that the highest contents of Ra-226, Th-232, and K-40 were present in Songkhla, with values of 93.7, 71.9, and 786.9 Bq kg−1, respectively, and the lowest contents were present in Khonkaen, with values of 15.6, 19.0, and 46.8 Bq kg−1, respectively. The results of our analysis of the activity concentrations of naturally occurring radionuclides helped explain the lower levels of radon gas and gamma-ray exposure in Khonkaen.