Peak expiratory flow variability, bronchial responsiveness, and susceptibility to ambient air pollution in adults

Bronchial hyperresponsiveness(BHR) and peak expiratory flow (PEF) variability are associated expressions of airway lability, yet probably reflect different underlying pathophysiologic mechanisms. We investigated whether both measures can be used interchangeably to identify subjects who are susceptible to ambient air pollution. Data on BHR ( ⩾ 20% fall in FEV1), PEF variability (ampl%mean PEF > 5% on any day during an 8-d period with low air pollutionlevels) and diary data on upper and lower respiratory symptoms, cough, and phlegmwere collected in 189 subjects (48–73 yr). The acute effects (lag0) of particulate matter with a diameter less than 10 μ m (PM10), black smoke, SO2 and NO2 on the prevalence of symptoms were estimated with logistic regression. In subjects with airway lability, both when expressed as PEF variability (69%) and BHR (28%), the prevalence of symptoms increased significantly with increasing levels of air pollution, especially in those with the greater PEF variability (n = 55, 29%). W...