Fourteen mild asthmatics (7 treated with inhaled corticosteroids) were exposed for 2 h in a road tunnel and a control environment, respectively, separated by at least 3 weeks. Symptoms and peak expiratory flow (PEF) were recorded. Seven hours following exposure sessions, subjects underwent measurements of fraction of exhaled nitric oxide (FENO), spirometry, and a bronchial provocation test. NAL, induced sputum and blood samples were collected.
The median PM2.5 and PM10 levels during the exposure occasions in the road tunnel were 80 (range 41–93) μg/m3 and 183 (72–213) μg/m3 respectively. Irritative symptoms from the airways increased and PEF decreased after road tunnel exposure. Increased levels of IL-10, IL-12 and TNF-α were observed in NAL fluid from subjects without ongoing inhaled corticosteroid treatment. Forced expiratory volume in 1 s (FEV1) and the degree of bronchial responsiveness in asthmatics did not change significantly after tunnel exposure.
We conclude that asthmatics exhibit increased symptoms, decreased PEF and signs of inflammatory response in the upper airways, after a 2 h road tunnel exposure. Our findings may further emphasize asthmatics as a vulnerable group to common air pollutants.