Assessment of background radionuclides and gamma dose rate distribution in Urban-setting and its radiological significance

Background: Awareness of the dangers associated with exposure to high radiation in the environment is necessary to avoid its health impact, especially when staying in-door. Method: Assessment of gamma dose rate and radionuclides in urban settings of Ota has been carried out using a hand-held gamma detector to determine the hotspot of high radionuclides concentration in the study area. In this study, eighteen (18) stations were covered, gamma dose rate and radio-nuclides (Uranium-238, Thorium-232, and Potassium-40) emitting from the subsurface were measured. Results: The result showed that the mean value for the measured dose rate of 45.06 nGh−1 is below the suggested value of 84 nGh−1 while the estimated mean values for the radionuclides are were 23.81, 45.35 and 77.82 Bq/kg respectively. The evaluated radium equivalent (Raeq), internal index (Hin), external index (Hex) and gamma index (Iy) ranges from 70.92 to 128.70 Bq/kg, 0.24 to 0.41, 0.19 to 0.35 and 0.25 to 0.46 respectively. Furthermore, the estimated value of the alpha index ranged between 0.05 and 0.15, and an annual effective dose rate from 0.33 to 0.55. The estimated mean value of excess cancer lifetime risk is 0.0015. Conclusions: Therefore, the study suggests that the study area is safe for the residents. However, radioactivity concentration emanating from the subsurface of the setting should be monitored to avoid the environmental-health implication of accumulation of low gamma-dose, which can cause cancer of the lung due to anthropogenic activities.