Radon levels and health risks in the artisanal and small-scale gold mines in Rwamgasa, Tanzania

Abstract

This research outlines the findings from measurements of radon levels and radiation exposure in the Rwamgasa artisanal and small-scale gold mine (RASGM) in Tanzania, which are crucial for evaluating radiogenic threats to both workers and the surrounding community. Data were obtained using both a continuous radon monitor CRM-510 and a portable radon monitor PRM-145. The concentration of radon gas in the active mining area ranged from 229.8 Bq/m³ to 342.5 Bq/m³, with an average of 302.5 Bq/m³. Residences situated near the mining area recorded an average radon level of 205.4 Bq/m³, fluctuating between 81.4 Bq/m³ and 327.5 Bq/m³, while inactive mining sites and the control zone displayed average readings of 75.8 Bq/m³ and 26.3 Bq/m³, respectively. The active mining sites and houses in the mining area reported average annual effective doses of 1.45 mSv/y and 0.98 mSv/y, respectively. In contrast, the estimates for inactive mining sites and the control area were 0.36 mSv/y and 0.13 mSv/y, respectively. These findings reveal significantly elevated levels in active compared to inactive areas, implying potential radiological health hazards for miners and the community. An analysis of indoor readings illustrated that the peak indoor radon concentrations over time varied considerably among the four sampled locations, including active mining pits, residences in the mining area, inactive mining pits, and the control area, with the mining pits and residences in the mining vicinity showing higher readings. This suggests that mining operations accelerate the levels of radon gas. This study provides one of the first comprehensive assessments of radon distribution, intake, and associated annual effective doses in artisanal and small-scale gold mining environments in Tanzania, while also comparing active mining pits, inactive pits, residential areas, and control locations to evaluate the influence of mining activities on radon variability.