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

Bronchial hyperresponsiveness (BHR) and peak expiratory flow (PEF) variabil ity are associated expressions of airway lability, yet probably reflect dif ferent underlying pathophysiologic mechanisms. We investigated whether both measures can be used interchangeably to identify subjects who are suscepti ble to ambient air pollution, Data on BHR (greater than or equal to 20% fal l in FEV1), PEF variability (ampl%mean PEF > 5% on any day during an 8-d pe riod with low air pollution levels) and diary data on upper and lower respi ratory symptoms, cough, and phlegm were collected in 189 subjects (48-73 yr ). The acute effects (lag0) of particulate matter with a diameter less than 10 mu m (PM10), black smoke, SO2 and NO, on the prevalence of symptoms wer e estimated with logistic regression. In subjects with airway lability, bot h when expressed as PEF variability (69%) and BHR (28%), the prevalence of symptoms increased significantly with increasing levels of air pollution, e specially in those with the greater PEF variability (n = 55, 29%). We found no such consistent positive associations in adults without airway lability . PEF variability, and to a smaller extent BHR, can be used to Identify adu lts who are susceptible to air pollution. Though odds ratios were rather lo w (ranging from 1.13 to 1.41), the impact on public health can be substanti al because it applies to large populations.