This study focuses on the simultaneous measurement of radon, thoron, and their associated progeny concentrations in the indoor air of dwellings in the townships of Bitkine, Mongo, Léré, and Pala in southern Republic of Chad. The objective is to evaluate the contribution of thoron gas and its associated progeny to the effective dose due to inhalation. Compared to the UNSCEAR mean value, the concentration values obtained in this study are relatively high in some locations within the study area. To assess the internal exposure due to radon, thoron, and their associated progeny, passive detectors of the Raduet type and thoron progeny monitors were deployed for three months in 150 dwellings in the study area. Using solid-state nuclear track detection, radon, thoron, and thoron progeny concentrations were directly measured, while radon progeny concentrations were indirectly measured. Their respective average values were 62, 60, and 8 Bq/m3 obtained through direct measurement, and 25 Bq/m3 obtained through indirect measurement. The average total effective dose through inhalation is estimated at 4.23 mSv/year. This value is higher than the worldwide average. Thoron gas and its associated progeny are the main contributors to this dose, ranging from 5% to 85% with an average value of 62%.
Patale Z. Ziebno (Sun,) studied this question.