Browsing by Author "Sawe, Shovi Furaeli"

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    Determinant of radon gas and respirable coal dust deconcetrations in the working environments of kiwira coal mine, sw Tanzania
    (University of Dar es Salaam, 2010) Sawe, Shovi Furaeli
    The main sources of respiratory health effects in underground mining operations are exposure to radon gas and its decay products as well as the exposure to respirable dusts. The extent of radon exposure in underground mining in Tanzania is still unknown since few studies on this subject have been conducted. Likewise, there have been few studies on exposure to respirable dust in Tanzania mines. In this study, the concentrations of radon gas and respirable coal dust have been estimated at Kiwira Coal Mine. For radon concentration measurements, a portable radon gas monitor (A1phaGUARD) was used and annual effective dose was estimated using the intake data and its dosimetric conversion coefficient. Respirable dust particles were collected on filters of 37 mm in diameter and pore size of 0.45 IM1 using a dichotomous sampler and quantified by gravimetric analysis. The lowest mean radon concentration of 36±5 Bq/m3 was measured at the main air intake and the highest mean radon concentration of 305±29 Bq/m3 was measured at the main air return. The overall mean dust concentrations were found to be 0.81 mg/m3, 1.07 mg/m3 and 2.50 mg/m3 for underground, washing plant and power plant, respectively. These results show that radon gas concentrations are below the action level of 500 —1500 Bq/m3 recommended by the ICRP. The corresponding annual effective doses from radon gas are also below the dose limit of 20 mSv/y. Dust concentration and the corresponding intake in the coal extraction area and coal processing plant were below the acceptable limit of 2 mg/m3. However, this limit was exceeded by 25 % in the pow er plant, which therefore requires intervention measures.