Assessment of mine ventilation systems and air pollution impacts on artisanal tanzanite miners at Merelani, Tanzania

Abstract

This article assesses mine ventilation systems and air pollution impacts on 4000 artisanal tanzanite miners at Merelani. Concentration of carbon monoxide (CO) in five selected mines averaged 66.2 ppm (with maximum of 102 ppm) which is 2.5 times higher than the maximum concentration specified by Ontario Ministry of Labour (2015). The average level of respirable dust was 8 mg dust/m3 air, which is 4 times higher than the allowable American guidelines for mines. Suffocation accidents consists of 29% of the total accidents in Merelani which claimed lives of 44 miners from 2005 to 2014. About 82% of the suffocation accidents were caused by unauthorized entry in temporary stopped or abandoned mines. Many miners suffer from silicosis and other lung diseases and 6.6% of miners have tuberculosis (TB). Based on the results of field studies it was found that small compressors being used for both drilling and ventilation are capable of providing 11.4 m3 of air/min in average. Usually 100 to 120 miners per shift are working in the mining fronts and this air quantity is not adequate to provide enough fresh air and comfort to workers and to dilute contaminants to a safe concentration. Interviews with managers of 50 mining fronts revealed that dry drilling is used by 92% and only 10% of miners wear masks. The study highlights the need of forced fans, dust control strategies, use of dust mask, pre and post medical checks, gas monitoring, training and abiding to safe mining practices as the measures to improve health and safety of the miners at the area.