ABSTRACT
A study of indoor radon was carried out on 319 different buildings in five districts (Amphurs Muang, Phuwiang, Khou-suankwan, ubolrat and Nampong) of Khonkaen Province in northeastern Thailand, using an activated charcoal canister for gaseous collection and a gamma spectrometer for analysis of the samples. The survey revealed the presence of radon gas inside all the buildings investigated, with overall concentrations being 15.33 + 22.13 bequerels/cubic metre and the prevalence rate of elevated values being 0.94 percent. The prevalence f higher indoor radon concentrations in Amphur Phuwiang (32.18+ 44.05) Bq.m-3) differs statistically from the concentrations encountered in the four other districts. In considering the age of the buildings and the type of building materials, the differences in indoor radon concentrations were not statistically significant. Indoor cigarette smoking and the inappropriate ventilation of the buildings appeared to relate to the higher radon concentrations.