Investigation of radon concentration and annual effective dose in selected caves in kakumiro and fort portal, western Uganda

Abstract

This study was conducted to determine radon concentration and annual effective dose in Amabere Ga Nyinamwiru cave and Semwama hill cave in Western Uganda using continuous radon monitor (Radon Sentinel model 1030). The radon concentration levels in Amabere caves for morning period (7:00-10:00), mid-morning period (10:00-1:00) and afternoon period (1:00- 4:00) varied from 14.27 ± 4.01 Bqm-3 to 17.70 ± 01 Bqm-3 with mean value of 15.90 ± 2.76 Bqm-3. The radon concentration in Semwama hill cave for morning period (7:00-10:00), mid-morning period (10:00-1:00) and afternoon period (1:00- 4:00) was found to vary from 447.3 ± 30.64 Bqm-3 to 507.63 ± 30.64 Bqm-3 with a mean value of 480.56 ± 30.64 Bqm-3. The annual effective dose for Amabere caves varied from 0.36 ± 0.10 mSvyr-1 to 0.44 ± 0.08 mSvyr-1 with an average value of 0.40 ± 0.07 mSvyr-1. The annual effective doses for Semwama hill cave ranged from 11.27 ± 0.77 mSvy-1 to 12.27 ± 77 mSvy-1 with mean value of 12.11 ± 0.77 mSvy-1. The Semwama Hill Cave effective dose data show that there is evidence of radon health risk to the general public and workers, as most of the values of yearly effective doses determined are more than 1 mSvy-1 as advised by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), International Commission on Radiological Protection (ICRP), and World Health Organization (WHO). Semwama hill cave, which has limited ventilation, has higher radon concentrations than Amabere caves. Further studies should be carried out on Semwama hill cave to ascertain the exposure levels to 222Radon gas as compared with a broad baseline measurement and future research should also look at the seasonal variations in the cave's radon concentration, equilibrium factor, and aerosol state, as well as an analysis of the tour guides' time spent there.