Assessment of Indoor and Outdoor Background Radiation Levels in the Faculty of Veterinary Medicine and College of Medical Sciences, Ahmadu Bello University, Zaria, Nigeria

Abstract

 Environmental radiation surveillance is a critical component in assessing radiological safety in institutions where ionizing radiation sources are routinely applied. This study evaluated indoor and outdoor background gamma radiation levels within selected locations in the College of Medical Sciences and the Faculty of Veterinary Medicine, Ahmadu Bello University, Zaria, Nigeria. Measurements were carried out at twenty (20) indoor and outdoor points using a portable gamma-ray spectrometer, while geographical coordinates were recorded with a handheld Global Positioning System (GPS) device. The acquired dose rates were subjected to statistical analysis and converted to annual effective dose rates for both indoor and outdoor environments using standard UNSCEAR conversion coefficients. The indoor absorbed dose rates ranged from 101.42 to 184.56 nGy/h, with an average value of 150.99 nGy/h. Outdoor dose rates varied from 96.50 to 173.00 nGy/h, with a mean value of 132.59 nGy/h. Correspondingly, the estimated annual effective dose ranged from 0.49 to 0.88 mSv/y for indoor environments, while outdoor values ranged from 0.12 to 0.27 mSv/y. The highest radiation level was observed at the Radiographic (Imaging) Facility. Nonetheless, all measured values were below the International Commission on Radiological Protection (ICRP) recommended public dose limit of 1 mSv/y. Spatial distribution analysis indicated moderate variability in radiation levels across the study area, with relatively elevated concentrations in laboratory and radiographic facilities. The findings suggest that current radiation levels within the investigated environment do not pose significant radiological health risks to students, staff, or visitors. However, continuous and periodic monitoring is recommended to ensure sustained compliance with international radiological protection standards.