Abstract

A significant contribution to natural exposure of humans is radon gas, which emanates from the soil and may concentrate in dwellings. The level of radon exposure varies around the globe, but limited data are available on the daily variations of indoor radon concentrations. In this study, indoor radon measurements were performed continuously within one week at six different places in Dalat, Vietnam using the real time Smart Radon Detector Radon Eye+. The indoor radon behavior in a day follows a sine pattern, with peak values in the early morning and lowest values in the late afternoon. There are also some fluctuations at specific times due to different weather conditions. Indoor radon concentrations in the Dalat regions were found to exceed the recommended guidelines and thresholds; excessive radon levels warranting health concern were found (150.7-340.0 Bq/m³). Some corrective actions to reduce indoor radon concentrations were recommended. Annual effective doses on different age categories were also calculated.