Prevalence and correlates of lung function impairment among open-pit miners at Nchanga in Zambia

Abstract

Background Mining operations contaminate the environment by emitting sizable quantities of dust particles or chemical emissions into the air which singly or in combination cause respiratory impairment if inhaled at adequate concentrations and over a long enough period of time. Studies in African countries, like Zambia, have shown that precautionary measures against dust inhalation at mineral extraction sites are generally poor or nonexistent. In Zambia, mining regulations do not have crystalline silica exposure limits. Many miners are therefore exposed to the harmful effects of silica dust which includes respiratory complications. This study was undertaken to determine the prevalence and correlates of impaired lung function among open-pit miners and also to add information to the body of knowledge on the relationship between mere exposure to dust measured by length of service in the mine and lung function impairment. Materials and Methods A cross-sectional study was conducted at the Nchanga open-pit mine in Chingola, Zambia. Informed consent to participate in the study was sought from each open-pit miner that was selected by stratified sampling method. Consenting open-pit miners were interviewed to get information on socio-demographic characteristics, respiratory symptoms, smoking, and also personal protective equipment. Further, the respondents also had their lung function measured using a spirobank G spirometer. The research was cleared by the biomedical ethics committee of the University of Zambia, school of medicine, Zambia. Data were entered, managed and analysed using EPI-DATA and SPSS (version 17) for windows. Results The response proportion to participate in the study was 93.9% (N=122). Most of the participants were of age 45-54. The prevalence rate of Lung function impairment was 27% (Severe; 4 (3.3%), Moderate; 5 (4.1%), and Mild 24 (19.7%)). It was found that the respondents who had cough first thing in morning (morning cough) were 3.44 times (CI=1.10, 10.70) more likely to have had lung function impairment than those who did not cough first thing in morning. Also, respondents who had chest tightness in the past year were 2.37 times (CI=1.22, 4.62) more likely to have had lung function impairment than those who did not have chest tightness in the past year. Conclusion/Recommendation No association was observed between duration of employment and lung function impairment hence the hypothesis did not hold and was rejected. Only morning cough and chest tightness were found to be significantly associated to lung function impairment and hence the correlates. It is therefore, recommended that respiratory symptom evaluation including spirometry be performed at least every year or so in order to check for the development of significant pulmonary symptoms. This may necessitate early intervention which may lead to reduced prevalence.