Assessment of annual effective doses from indoor radon and thoron in Doi Lo, Chiang Mai, Thailand

Abstract This study aimed to determine the annual effective dose resulting from radon and thoron progeny inhalation. The levels of radon, thoron, and progeny were assessed in residences situated in the Doi Lo region of Chiang Mai, Thailand. Indoor radon and thoron concentrations were detected using passive discriminative detectors. Using a progeny deposition rate detector, this study evaluates radon and thoron progeny [equilibrium-equivalent radon concentration (EERC) for radon and equilibrium-equivalent thoron concentration (EETC) for thoron]. Data were collected from 44 dwellings between March and May 2020. The results found that indoor radon concentrations ranged from 17 to 118 Bq m−3, while thoron concentrations ranged from 12 to 72 Bq m−3. The radon progeny (EERC) ranged from 4 to 173 Bq m−3, whereas thoron progeny (EETC) ranged from 1 to 15 Bq m−3. The total annual effective dose received from radon and thoron progeny inhalation varied from 0.5 to 5 mSv y−1.