[Effects of air pollutants on pulmonary function and bronchial reactivity in patients with chronic obstructive...

Exposure to polluted air can cause respiratory symptoms in subjects with airflow limitation. Twelve COPD (chronic obstructive pulmonary disease) patients with mild to moderate obstructive ventilatory defects were exposed on separate occasions to fresh ambient air and polluted air collected from the Lin-Sun S. Road tunnel in Taipei City. Concentrations of SO2 and NO2 were 85-121 ppb and 449-502 ppb, respectively, and were 4-fold and 10-fold, respectively, higher than those of out-door air in the city. Twenty healthy adult volunteers served as the control group. Maximal expiratory flow-volume determination, respiratory resistance (Rrs) and methacholine bronchial challenges were completed before and after inhalation of polluted air for 20 minutes. No difference in FVC (forced vital capacity), FEV1 (1 second forced expiratory volume), Rrs and bronchial reactivity was noted for normal subjects after inhaling polluted air and ambient air. For patients with COPD, there was a small but significant decrease in FEV1 after exposure. The elevation in Rrs was prominent, and there was also a significant increase in bronchial sensitivity to methacholine (decrease in cumulative provocation dose, DA) in positive responders. We conclude that short-term exposures to moderate polluted air can affect lung function and increase bronchial sensitivity to methacholine in COPD patients.