Sputum neutrophilia and annual decline of FEV1 in dust exposed workers

In a previous study in the smelting industry we found a significant relationship between dust exposure and accelerated annual decline in FEV1. The aim of the present study was to investigate the association between annual decline in lung function and different inflammatory markers in induced sputum from the production workers. Methods: Employees (n=76 (27 current smokers)) who had been part of a longitudinal study (9-13 years) including spirometry (>6 measurements) and respiratory questionnaires, performed induced sputum and exhaled NO. Results: All workers had neutrophil inflammation compared to unexposed controls. However neutrophil levels in sputum samples did not differ between workers with annual decline in FEV1 (>45ml - upper tertile) compared to workers with annual decline in FEV1 Conclusion: All production workers displayed airway inflammation characterized by neutrophilia. Surprisingly, there were no differences in the neutrophil level when comparing workers with rapid decline in lung function with those with slow decline in lung function. As expected smokers had low levels of exhaled NO, but there was no difference in neutrophil levels between smokers and non-smokers. Sputum neutrophilia was not a marker for increased decline in FEV1.