Exercise-induced bronchoconstriction and exercise-induced respiratory symptoms in workers exposed to tea dust.

Assuming that airborne particles and pollutants are important contributing factors in the development of exercise-induced bronchoconstriction (EIB), we performed a case-control study including 63 tea workers (36 men and 27 women, aged 36-55, duration of employment 3-30 years) and an equal number of office workers, matched by sex and age. Exercise-induced respiratory symptoms were recorded in a questionnaire. Skin prick tests, spirometry, as well as exercise and histamine challenge were carried out. Environmental measurements were performed on site during the work shifts. The prevalence of self-reported exercise-induced respiratory symptoms and EIB did not differ significantly between the exposed and control group (41.6% vs 36.8%, and 6.4% vs 4.8%, respectively). In both exposed and control workers, EIB was strongly linked to asthma (P < 0.01). In the exposed workers it was significantly associated with positive family history of asthma (P < 0.01) and positive family history of atopies (P < 0.05), whereas in the exposed smokers it was significantly related to smoking duration (P < 0.05). Bronchial reaction to exercise in the exposed smokers was significantly greater than in control smokers (P < 0.05). Self-reported exercise-induced respiratory symptoms were weakly associated with EIB, with a large proportion of false positive and a low proportion of false negative results in both groups.