ABSTRACT
A study of indoor was carried out on 615 different building in Rayong Province, Thailand, using an activated charcoal canister for sample collection and a gamma spectrometer for analysis of the samples. The survey revealed the presence of radon gas inside all the buildings investigated, varying in concentrations from 4.00 to 74.15 becquerels/cubic metre (13.23+8.97 Bq.M-3). Although the levels of radon encountered were well below the safety threshold of 148 Bq.M-3 established by the U.S. Environmental Protection Agency, there were statistically significant difference between some districts. With regard to the type, age and ventilation status of the buildings, and the occupant’s practice of smoking indoor, the findings of this investigation do not warrant a conclusion that would support the notion of these factors contributing to, or being mutually associated with, indoor gaseous concentrations of radon.