Short-term effect of exposure to suspended particulate matter (PM10) on the respiratory function of urban asthmatic and control adults

The aim of this study was to assess the effects of PM10 daily concentrations in urban ambient air on bronchial reactivity and on two indices of respiratory function (FEV1 and PEF) of healthy control (n = 20) and of mild asthmatic adults (n = 20). The study took place over two periods of a month and a half, during summer 1996 and winter 1997. Each volunteer underwent two methacholine challenge tests, one during a weekday, the other early on the next Monday morning, after a weekend of lower exposure. They also monitored their FEV1 and PEF twice daily with an electronic peak flow meter. The respiratory function decreased among asthmatic subjects a few days after daily PM10 levels had increased (−1.25% for FEV1, 95% CI = [−0.58, −1.92]; and −0.87% for PEF [−0.1, −1.63], for a daily 10 μg m−3 variation of PM10 in summer; −0.25% [−0.51, 0.02] for FEV1 only in winter). No association between daily variations of respiratory function and PM10 was observed among control subjects. Bronchial reactivity was not significantly different between the two days of methacholine tests among asthmatic and control subjects, either in summer or in winter. This study confirms the greater sensitivity of asthmatic adults, compared with healthy subjects, to short-term variations of ambient air concentrations of particles. However, bronchial reactivity is not modified by small short-term variations of particulate pollution among mild asthmatics or healthy subjects. Copyright © 1999 John Wiley & Sons, Ltd.