ESTIMATION OF ANNUAL EFFECTIVE DOSE FROM SOIL-GAS RADON IN SELECTED REGIONS OF ILORIN, NIGERIA

Abstract

- In recent times, researchers have shown an increasing interest in the study of radioactive gas radon due to its radiological health hazard. Soil-gas radon (222Rn) concentrations vary from place to place and human exposure level varies from one region to the other. The annual effective dose is commonly used for prospective assessment of yearly radiation dose received by the public for the purpose of optimization and planning in radiation protection within and around regions of high radioactivity concentration. In this study, soilgas radon concentrations were measured in-situ at 100cm below the ground from ten (10) locations with granite rock basement within Ilorin using RAD7, a solid-state radon detector manufactured by Durridge Company (USA). Results of radon concentrations varied from 17.54 ± 500.59 Bq/m3 to 1833.66±892.00 Bq/m3 with an average value of 387.193±218.47 Bq/m3 . The estimated annual effective dose attributed to the inhalation of 222Rn concentrations ranged from 0.00017 mSv/y at ASD location to 0.01735 mSv/y at TK location with average value of 0.00037 mSv/y in the study area. The obtained 222Rn concentrations in all locations were found below the tolerable levels which range from (400 to 40,000) Bq/m3 . However, locations WS (543.67± 465.52) Bq/m3 and TK (1833.66±892.00) Bq/m3 showed values above 400 Bq/m3 minimum range but below 40, 000 Bq/m3 maximum range of the world range limit. Overall, values of annual effective dose in all locations of the study area are below the 1 mSv/y dose limit recommended for radon inhalation from all sources. From the result of this study, it is safe to conclude that dwellers within the study area have no radiological health concern due to soil-gas radon.