Estimation of Indoor Radon and Its Progeny in Dwellings of Akoko Region, Ondo State, Southwestern Nigeria

Abstract

Radon gas is by far the most important source of ionizing radiation among those that are of natural origin. In this study, radon was measured in some homes built of different types of building materials in Akoko region of Ondo state, Nigeria. The test was conducted using Accustar alpha track long term passive test devices containing CR-39 solid state nuclear track detector foil. The detectors were exposed for a period of six months. After removal the detectors were subsequently etched electrochemically and counted with computer aided image analysis system. The results show that radon concentration varies between 15.00 Bqm-3 to 141.00 Bqm-3 with a mean of 35.54 Bqm-3 and geometric mean of 29.95 Bqm-3. Annual exposure varied between 0.10 WLM to 0.17 WLM with a mean of 0.13 WLM, annual effective dose varied between 0.38 mSvy-1 to 0.69 mSvy-1 with a mean of 0.50 mSvy-1 and lifetime fatality risk varied between 0.50x10-4 to 0.85x10-4 with a mean of 0.64x10-4 in bedroom, living room, store and lobby. This study shows that the local soil origin greatly contributes to radon concentrations recorded in these areas.