Air pollution exposure and COPD among miners, ex-miners and non-miners in Northern Tanzania: A cross-sectional study

Abstract

Background: There is a substantial burden due to Chronic Obstructive Pulmonary Disease (COPD) contributes to a substantial burden of diseases in developed countries. The existing unregulated mining activities in Africa, often without proper protective gear, could expose miners to excessive air pollution levels and subsequent development of COPD. Methods: We conducted a case – control study in small-scale, informal, hard-rock mining site in Northern Tanzania. We recruited all eligible active miners and ex-miners and matched non-miners aged ≥30 years. We collected data on respiratory symptoms and risk factors using the BOLD questionnaire and performed spirometry with COPD defined based on post-bronchodilator FEV 1 /FVC<70%. We monitored air pollution based on PM 10 level in underground mining pits using TSI Side Pak TM AM510 samplers. Results: A total of 851 men ⦋577 active miners, 211 ex-miners and 63 non-miners⦌ were recruited with a mean age of 40.95 ± 9.21 years and two-thirds were cigarette smokers. About 83% of all respondents completed the questionnaires and underwent post-bronchodilator spirometry. The prevalence for COPD was estimated at 15.20%, 17.10% and 15.40% for active miners, ex-miners and non-miners respectively. Over 18% of current cigarette smokers had significant nicotine dependence which was associated with the duration of smoking (p= 0.028) and the number of pack years (p= 0.002). The majority of COPD patients presented with cough and had frequent exacerbations but with mild to moderate airway limitation. The majority of ex-miners presented with dyspnoea and had poor FEV 1 and FVC parameters. About 25% of COPD patients reported a history of pulmonary tuberculosis. The survey revealed up to 20000µg/m 3 of PM 10 in the underground drilling points; 400-fold higher than the acceptable WHO limits. Conclusion: There is high prevalence of COPD among small-scale miners in Tanzania. The patients are largely young and many are smoking cigarettes. The mining activities are typically carried out without protective gear. There is widespread lack of awareness of COPD and often people received inappropriate diagnosis and therapy.