Abstract
BackgroundFew studies of miners have been carried out in African countries; most are from South Africa, where the working conditions are assumed to be better than in the rest of Africa. Several studies have focused on respiratory disorders among miners, but development workers responsible for creating underground road ways have not been studied explicitly. This is the first study assessing the associations between exposure to dust and quartz and respiratory symptoms among coal mine workers in a manually operated coal mine in Tanzania, focusing on development workers, as they have the highest exposure to coal dust.MethodsA cross-sectional study was carried out among 250 production workers from a coal mine. Interviews were performed using modified standardized questionnaires to elicit information on occupational history, demographics, smoking habits and acute and chronic respiratory symptoms. The relationships between current dust exposure as well as cumulative respirable dust and quartz and symptoms were studied by group comparisons as well as logistic regression.ResultsWorkers from the development group had the highest dust exposure, with arithmetic mean of 10.3 mg/m3 for current respirable dust and 1.268 mg/m3 for quartz. Analogous exposure results for mine workers were 0.66 mg/m3 and 0.03 mg/m3, respectively; and for other development workers were 0.88 mg/m3 and 0.10 mg/m3, respectively.The workers from the development section had significantly higher prevalence of the acute symptoms of dry cough (45.7%), breathlessness (34.8%) and blocked nose (23.9%). In addition, development workers had significantly more chronic symptoms of breathlessness (17.0%) than the mine workers (6.4%) and the other production workers (2.4%). The highest decile of cumulative exposure to respirable dust was significantly associated with cough (OR = 2.91, 95% CI 1.06, 7.97) as were cumulative exposure to quartz and cough (OR = 2.87, CI 1.05, 7.88), compared with the reference consisting of the group of workers with the lowest quartile of the respective cumulative exposure.ConclusionThe development workers in a coal mine had more acute and chronic respiratory symptoms than the mine and the other production workers. In addition, there was an association between high cumulative coal dust and respiratory symptoms.
Highlights
Few studies of miners have been carried out in African countries; most are from South Africa, where the working conditions are assumed to be better than in the rest of Africa
There was an association between high cumulative coal dust and respiratory symptoms
The results indicate an association between dust exposure and respiratory symptoms, since stratification by smoking habits did not alter the significant difference in the prevalence of cough as much as 4–6 times a day for 4 days or more in a week and shortness of breath walking with people of own age between the groups; but a cross-sectional study cannot confirm causal relationships
Summary
Few studies of miners have been carried out in African countries; most are from South Africa, where the working conditions are assumed to be better than in the rest of Africa. Various studies from industrialized countries have documented the relationship between exposures to coal dust and increased respiratory symptoms Both longitudinal and cross-sectional studies [3,4,5,6,7,8] have shown that symptoms of persistent cough and phlegm production, breathlessness and wheezing relate significantly with individual cumulative exposure to respirable mixed coal dust. The US Coal Mine Health and Safety Act in 1969 set the legal respirable mixed coal dust standard for coal mines in the United States at 3 mg/m3, with a reduction to 2 mg/m3 in 1973 Despite these standards, studies in the United States showed statistically significant associations between cumulative exposure to respirable dust and respiratory symptoms for miners joining the industry after 1970 [10]. This study suggested that respiratory symptoms might provide an early warning related to prior exposure and might be followed by impairment in lung functioning
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