A cross-sectional study of exposures, lung function and respiratory symptoms among aluminium cast-house workers

Objectives To investigate exposures, respiratory symptoms, lung function and exposure-response relationships among aluminium cast-house workers. Methods A cross-sectional study was conducted among 182 workers. Exposure data were used to model exposure to irritants. Lung function and questionnaire data on respiratory symptoms were compared to a general population sample and an internal reference group. Blood samples were taken from 156 workers to examine total IgE, eosinophils and sensitisation to common allergens. Results Average daily mean exposure to inhalable dust, metals, hydrogen fluoride, fluoride salts and sulphur dioxide was relatively low compared to reference values. Airflow patterns in the hall were disturbed regularly and resulted in pot emissions with high concentrations of fluorides. Peak exposures to chlorine gas occurred intermittently due to production process disturbances. Workers reported significantly more respiratory symptoms (continuous trouble with breathing (prevalence ratio (PR) 2.5; 95% CI 1.2 to 5.3), repeated trouble with breathing (PR 1.8; 95% CI 1.1 to 3.0), wheezing (PR 1.4; 95% CI 1.1 to 1.8), asthma attack (ever) (PR 2.8; 95% CI 1.7 to 4.6) and doctor diagnosed asthma (PR 2.6; 95% CI 1.5 to 4.4). Regression analysis showed significantly lower FEV1 values (-195 ml) and FVC values (-142 ml) compared to a general population sample. Lung function did not differ between groups. Conclusion This epidemiological study suggests cast-house workers in the aluminium industry are exposed to respiratory hazards. Exposure-response relationships could not be demonstrated but this study supports preventive measures in the work environment with a focus on (peak) exposures to irritants.