Blood eosinophils in workers with aluminum potroom asthma are increased to higher levels in non-smokers than in smokers

Abstract

Background: Aluminum potroom asthma (PA) has been described in several reports. This study aimed to investigate the association between blood eosinophils and PA.

Methods: In a cross-sectional study, 338 workers were examined as follows: spirometry, blood eosinophils, skin prick test, and work exposure measurements. They also completed a questionnaire on respiratory symptoms, smoking, allergy, and duration of work exposure.

Results: The odds ratio for PA was 4.2 (95% confidence interval 1.5-9.7) for workers with eosinophils > or =400 x 10(6) cells/L compared with workers with eosinophils <200 x 10(6) cells/L. In non-smokers, the number of eosinophils was 177 x 10(6) cells/L (P < 0.001) higher among workers with PA than asymptomatic workers, whereas the corresponding difference among current smokers was only 63 x 10(6) cells/L (P = 0.03).

Conclusions: The prevalence of PA was positively associated with blood eosinophils. An attenuation of the blood eosinophil increase was observed in smoking asthmatics, suggesting an immune-modulating effect of smoking.