Empirical Investigation of Indoor Radon Concentration Levels in Residential Buildings of Jos, Plateau State and Associated Health Risk

Indoor radon accumulation in residential buildings above the WHO reference level of 100 Bq/m3 is the second leading cause of lung cancer globally, yet comprehensive indoor radon surveys in Nigerian residential stock remain sparse. This study empirically measures indoor radon concentrations in 120 residential buildings across three urban districts and two peri-urban areas of Jos, Plateau State, North Central Nigeria, using passive radon dosimeters based on CR-39 track-etch detectors deployed for 90-day exposure periods. Building characteristics including construction type, floor level, ventilation rate, and floor material were recorded through structured surveys. Measured radon concentrations are correlated with building characteristic variables using multivariate regression to identify significant structural predictors of indoor radon levels. Occupant annual effective dose from radon inhalation was estimated using ICRP dose conversion factors accounting for equilibrium fraction and indoor occupancy patterns consistent with Nigerian household activity surveys. Annual excess absolute risk of lung cancer was calculated using the BEIR VI risk model. Results indicate geometric mean indoor radon concentration of 68 Bq/m3 with individual building values ranging from 18 to 312 Bq/m3. Fourteen percent of sampled buildings exceeded the WHO 100 Bq/m3 reference level. Basement-level rooms and buildings with granite aggregate concrete foundations showed significantly higher radon concentrations. The study provides the first statistically representative indoor radon dataset for Jos and estimates that approximately 2.1 additional lung cancer deaths per 100,000 population per year are attributable to radon in the assessed building stock. Keywords: indoor radon, residential building, health risk, Plateau State, lung cancer