Effects of ambient air pollution on upper and lower respiratory symptoms and peak expiratory flow in children

Background Previous epidemiological studies have shown acute effects of inc reased amounts of ambient air pollution on the prevalence of respiratory sy mptoms in children with respiratory disorders. We investigated whether chil dren with bronchial hyperresponsiveness (BHR) and relatively high serum con centrations of total IgE (>60 kU/L, the median value) are susceptible to ai r pollution. Methods We collected data from children during three winters (1992-95) in r ural and urban areas of the Netherlands. Lower respiratory symptoms (wheeze , attacks of wheezing, shortness of breath), upper respiratory symptoms (so re throat, runny or blocked nose), and peak expiratory flow were recorded d aily for 3 months. The acute effects of airborne particulate matter with a diameter of less than 10 mu m, black smoke, sulphur dioxide, and nitrogen d ioxide were estimated by logistic regression. Findings 459 (73%) of 632 children had complete data. Of these, 26% had BHR and relatively high (above median) serum total IgE, 36% had no BHR and tot al IgE of 60 kU/L or less, 15% had BHR and total IgE of 60 kU/L or less, an d 23% had a total IgE of more than 60 kU/L but no BHR. In children with BHR and relatively high serum total IgE the prevalence of lower respiratory sy mptoms increased significantly by between 32% and 139% for each 100 mu m/m( 3) increase in particulate matter, and between 16% acid 131% for each 40 mu m/m(3) increase in black smoke, SO2, or NO2. Decrease in peak expiratory f low of more than 10% in that group was more common with increased airborne particulate matter and black smoke. There were no consistent positive or ne gative associations between increased air pollution and prevalence of respi ratory symptoms or decrease in peak expiratory flow in the other three grou ps of children. Interpretation Children with BHR and relatively high concentrations of seru m total IgE are susceptible to air pollution. Although our odds ratios were rather low (range 1.16-2.39) the overall effect of air pollution on public health is likely to be substantial since these odds ratios refer to large numbers of people.