Assessment of Radon Gas Concentration in Groundwater Wells in Kano State

Radon is a naturally occurring radioactive gas generated by the decay of uranium and radium within rock and soil matrices, with elevated concentrations in groundwater posing inhalation and ingestion health risks to consuming populations. Kano State, situated in the North West geopolitical zone of Nigeria, overlies basement complex terrain containing uranium-bearing pegmatites and granitic rocks that may constitute significant radon sources. This study measures radon concentrations in groundwater obtained from boreholes and hand-dug wells distributed across six local government areas of Kano State, comparing results against WHO and USEPA permissible limits. Radon measurements were conducted using the RAD-7 electronic radon detector with the Big Bottle Radon-in-Water accessory following established field protocols. Concurrent measurements of uranium and radium content in selected samples were performed by inductively coupled plasma mass spectrometry to assess the geochemical source relationship. The spatial distribution of radon activity is evaluated against the geological map of the area to identify lithological controls on elevated radon occurrences. Risk assessment indices including annual effective dose and excess lifetime cancer risk were calculated for communities utilising wells with high radon concentrations. Findings are communicated to the Kano State Ministry of Environment and the National Nuclear Regulatory Authority to support protective measures. This study advances geogenic health hazard understanding in North West Nigeria. Keywords: radon, groundwater, radioactivity, Kano State, health risk assessment.