Estimation of effective dose rates caused by radon and thoron for inhabitants living in rare earth field in northwestern Vietnam (Lai Chau province)

Forty six houses at three typical inhabitant villages that are located in the rare earth field in northwestern Vietnam were surveyed for radon and thoron concentrations. The measurements were conducted by exposing alpha track detectors CR-39 inside and outside of dwellings for 4 months. The results showed that houses adjacent to the rare earth ore bodies have significantly elevated radon concentrations. Annual committed effective doses originated from the inhalation of radon and thoron were estimated. The results showed that people living in the ore bodies areas would be exposed to the dose that could be 10 times higher than the world average.