SIMULTANEOUS INDOOR RADON, THORON AND THORON PROGENY MEASUREMENTS IN BETARE-OYA GOLD MINING AREAS, EASTERN CAMEROON

Abstract Indoor radon (Rn), thoron (Tn) and thoron progeny (TnP) were simultaneously measured in the gold mining areas of Betare-Oya using RADUET detectors and TnP monitors. Rn and Tn concentrations range between 88–282 and 4–383 Bq m−3, respectively, with the arithmetic means of 133 ± 39 and 93 ± 76 Bq m−3. The 76% of houses for Rn and 25% for Tn exceed the WHO reference level of 100 Bq m−3 and 3% of the houses exceed the ICRP threshold of 300 Bq m−3. The equilibrium equivalent thoron concentration ranges between 1 and 19 Bq m−3 with a mean value of 6 ± 4 Bq m−3. The thoron equilibrium factor ranges between 0.01 and 0.55 with arithmetic mean of 0.11, higher than the world average value of 0.02 given by UNSCEAR. The total inhalation dose due to Rn, Tn and their progeny ranges between 1.8 and 6.2 mSv y−1 with the arithmetic mean of 3.8 ± 1.1 mSv y−1.