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

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, skinprick test, and work exposure measurements. They also completeda 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 >= 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) cellsIL (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.