THE ASSOCIATION OF AMBIENT AIR-POLLUTION WITH TWICE-DAILY PEAK EXPIRATORY FLOW-RATE MEASUREMENTS IN CHILDREN

A stratified sample of 83 children living in Uniontown, Pennsylvania, reported twice daily peak expiratory flow rate (PEFR) measurements on 3,582 child-days during the summer of 1990. Upon arising and before re tiring, each child recorded the time, three PEFR measurements, and the presence of cold, cough, or wheeze symptoms. Ambient air pollution, i ncluding particle-strong acidity, was measured separately during the d ay (8 a.m. to 8 p.m.) and at night. Each child's maximum PEFR for each session was expressed as the deviation from his or her mean PEFR over the study and adjusted to a standard of 300 liters/minute. The sessio n-specific average deviation was then calculated across all of the chi ldren. A second-order autoregressive model for PEFR was developed, whi ch included a separate intercept for evening measurements, trend, temp erature, and 12-hour average air pollutant concentration weighted by t he number of hours each child spent outdoors during the previous 12-ho ur period. The results are expressed in terms of the interquartile ran ge for each pollutant. A 12-hour exposure to a 125-nmol/m(3) increment in particle-strong acidity was associated with a -2.5 liters/minute d eviation in the group mean PEFR (95% confidence interval (CI) -4.2 to -0.8) and with increased cough incidence (odds ratio (OR) = 1.6, 95% C I 1.1 to 2.4). A 30-ppb increment in ozone for 12 hours was associated with a similar deviation in PEFR levels (-2.8, 95% CI -6.7 to 1.1). T he association between PEFR and particle-strong acidity was observed a mong the 60 children who were reported as symptomatic on the prior sym ptom questionnaire (-2.5, 95% CI -4.5 to -0.5). The authors conclude t hat summer occurrences of excessive acid aerosol and particulate pollu tion are associated with declines in peak expiratory flow rates in chi ldren.