Annual effective dose from radon-222 concentration levels in underground water in bungoma south sub - county, Kenya

This research measured the concentration levels of radon in groundwater and determined the ingestion and inhalation dose. The study used RAD7 detector with RAD7-H2O accessory from Durridge Company to determine the radon levels. Thirty water samples in granitic dominated regions were collected from various areas of Bungoma County: ten from boreholes (BH), ten from hand dug wells (WL) and ten from springs (SP). The water samples were collected in 250 ml bottles which were tightly covered with lid to avoid radon leakage. The highest value was 303±4.00 KBq/m3 recorded in Kanduyi well and the lowest was 126±11.4kBq/m3 from where most of the samples recorded a high radon concentration with a mean of 269±5.25 KBq/m3 in wells, 213±7.96 KBq/m3 in boreholes and 290±7.70 KBq/m3 in springs. The average ingestion dose was found to be 1.5±0.07mSv/yr, 1.9±0.09 mSv/yr and 2.1±0.1 mSv/yr. The average annual effective dose rate for the samples collected were 2±0.1 mSv/yr for boreholes, 2.6±0.13 mSv/yr for wells and 2.7±0.14 mSv/yr for springs. The samples reported an average value of AED higher than the world average of 1.15 mSv/yr but below the exception limit of recommended action level of 10 mSv/yr hence the radon concentration levels in underground water in the study area has minimal health implications to the population.