Measurement of radiation exposure rate around quarry sites in Ekiti state, Nigeria

Risk assessment monitoring is crucial for protecting humans from harmful ionizing radiation. This study assessed radon concentration, annual dose rate, annual effective dose, and estimated life cancer risk at 10 major quarry sites in Ekiti State, using a digital portable survey meter and gamma scout. Measurements were taken at various locations, including nearby offices and residential buildings, for comparison. Results showed radon concentrations ranging from 1.0 to 59.50 Bq/m³, annual dose rates from 0.025 to 1.501 mSv/y, and annual effective doses from 0.060 to 3.602 mSv/y. The mean gamma emission dose rates varied from 0.24 ± 0.040 to 0.455 ± 0.045 µSv/h, with annual effective doses between 0.438 ± 0.070 and 0.797 ± 0.079 mSv/y. The estimated life cancer risk (ELCR) averaged 2.14 × 10⁻³, exceeding global acceptable levels. While most non-quarry sites had radon levels below WHO reference levels, site 3 exceeded these limits. Gamma dose rates at all sites were within safe limits. However, the higher ELCR values suggest potential long-term health risks from low-level radiation exposure, warranting ongoing monitoring.