Activity Concentration of Rn Measured in Drilled and Dug Well Drinking Waters and Resulting Radiation Doses to Population of Ogun State, Nigeria

Radon studies have been conducted in many countries of the world in indoor air but such studies in drinking waters are sparse. We present the results of Rn activity concentration measurements in drilled and dug well drinking waters from three large cities in Ogun State, southwestern Nigeria. The measurements were done suing high-resolution high-purity germanium (HPGe) detector (Canberra Industries Inc.). Measured Rn ranged from 0.26±0.01 to 0.88±0.09 Bq l and 0.25±0.02 to 0.72±0.10 Bq l in the drilled wells and dug wells respectively. The activity concentrations were used with ingested dose conversion factors to estimate annual effective dose rates due to ingestion of Rn as a result of the consumption of water from these wells. Estimated annual effective dose rates ranged from1.32±0.11 Sv y 1 (in a dug well) to 4.66±0.48 Sv y (in a drilled well); 0.11±0.10 to 1.71±0.18 Sv y and 0.64±0.05 to 2.25±0.23 Sv y for infants (0 – 1y), children (2 – 7y) and adults ( 17 y) respectively. All these values fall below the World Health Organisation (WHO) recommended limit of 0.1mSv y for public exposure for all ages.