Assessment of radon level and the associated radiological risk from soil samples of quarry area at Hakim Gara, Ethiopia

Excavation of terrestrial surface of the Earth could enhance the chance of exposure to radon while gases in the underground get access to escape. This study was aimed to assess the level of radon concentration from soil samples of quarrying sites at Hakim Gara in Ethiopia using CR-39 detectors in sealed container technique. The results of the measured radon concentration level were ranging from 164.3 to 494.0 Bq/m³ with average value of 295.7 ± 87.09 Bq.m⁻³. The activity concentration value of radium ranging from 0.63 to 2.74 Bq.kg⁻¹ with average value of 1.59 ± 0.55 Bq.kg⁻¹. The radon surface exhalation rate ranging between 0.95 to 4.1 Bqm⁻² h⁻¹ with mean value of 2.38 ± 0.83 Bqm⁻² h⁻¹. The mass exhalation rate ranging between 0.01 and 0.11 Bqkg⁻¹ h⁻¹ with average 0.06 ± 0.03 Bqkg⁻¹ h⁻¹. The AED and ELCR values for the study area were calculated and the mean value of the quarry area were determined on the basis of altitude variation and found to be different for individual and group sample locations. Compared to values recommended by WHO for outdoor radon exposure, the measured levels of radon concentration were observed to be higher in the study area. But residential areas under construction in the area need further studies since the measured and calculated values were high for indoors in some soil samples.