Estimation of activity concentrations of radionuclides and their hazard indices in coastal plain sand region of Ogun state

Assessment of natural background radionuclides emanating from the subsurface geological features was carried out with the use of gamma-ray spectrometry at various locations at one of the secondary school in Canaan land, Ota, Ogun State. The activity concentrations of 226 Ra, 232 Th and 40 K were revealed to be 12.66 ± 0.76–42.33 ± 1.37, 44.96 ± 1.41–128.70 ± 1.56, 31.30 ± 1.18–453.85 ± 2.43 Bq kg −1 respectively. The mean value of 232 Th reported higher than the world reference standard of 50 Bq kg −1 . Moreover, the stations closest to the school’s laboratory were noticed to be prone to more gamma radiations than the other buildings in the school. Similarly, the results of the radiological parameters estimated varied between 86.04–243.7 Bq kg −1 , 40.02–115.4 nGy h −1 , 0.049–0.142 mSv y −1 and 0.232–0.658 for Ra eq , D (out) , AEDE and H ex , respectively. Although, the results of the radiological parameters did not exceed the world safe limits, higher values of these parameters were reported at some stations closer to the school laboratory. It can be concluded that the school laboratory is prone to more gamma radiation than the class rooms and the administrative block. Therefore, the laboratory instructors and staff, who spend longer time in the laboratory, are more liable to the health risk that could result from years of exposure to gamma radiation in the laboratory.