Indoor Radon Concentration and Ventilation Rate in Some Elementary Schools in Ibadan, Nigeria

Abstract

Introduction: This study aimed to find the correlation between indoor radon concentration and ventilation rate in some selected elementary schools in Ibadan, Southwestern Nigeria. The schools and the rooms were selected on the basis of different natural ventilation conditions. Materials and methods: The measurements of indoor radon concentrations were performed by using a passive diffusion cup technique fitted with CR-39 detectors. The values of indoor radon concentration vary from 103 Bq/m 3 to 362 Bq/m 3 with an average value of 196 Bq/m 3. However, the value of effective dose ranged between 0.65 mSvy-1 and 2.28 mSvy-1 , with an average value of 0.45 mSvy-1. The approximate natural ventilations rates of the selected rooms were calculated using ventilation formulae. The measurements were aimed to investigate the effect of ventilation rate on indoor radon concentration. Results: The results of the present study indicate that there is a high correlation between radon concentration and ventilation rate. Ventilation rate is inversely proportional to indoor radon concentration. By and large, all the results of indoor radon concentration are found to be lower than the recommended action level (1000-1500 Bq/m 3) for workplaces by the International Commission of Radiation Protection (ICRP). Also, the values of the effective dose levels are found to be lower than the average value of 10 mSvy-1. Conclusion: Radon concentration is expected to be higher during the cold season when ventilation would be low. Therefore, there is need to improve on ventilation and other means of mitigation in some classrooms where radon concentrations were relatively high.