AMBIENT OZONE CAUSES UPPER AIRWAYS INFLAMMATION IN CHILDREN

Ozone constitutes a major air pollutant in Western Europe. During the summer national air quality standards are frequently exceeded, which justifies concern about the health effects of ozone at ambient concentrations. We studied upper airways inflammation after ozone exposure in 44 children by repeated nasal lavages from May to October 1991. During this time period five to eight lavages were performed for each child. On 14 days following high ozone exposure (daily maximum greater-than-or-equal-to 180 mug/m3) 148 nasal lavages were performed, and on 10 days following low ozone exposure (daily maximum less-than-or-equal-to 140 mug/m3) 106 nasal lavages were performed. A significant increase of intra-individual mean polymorphonuclear leukocytes (PMN) counts from low ozone days (median, 20.27 x 10(3)) to high ozone days (median, 27.38 x 10(3); p < 0.01) was observed. Concomitant with a decrease of ozone concentrations in the fall mean PMN counts showed a downward trend. Linear regression analysis of log-PMN counts yielded a significant effect for ozone (p = 0.017). In a subsample humoral markers of inflammation were measured for each child's highest and lowest exposure. A significant increase was observed for eosinophilic cationic protein (median, 3.49 mug/L on low ozone days versus 5.39 mug/L on high ozone days; p < 0.05) and myeloperoxidase (median, 77.39 mug/L on low ozone days versus 138.6 mug/L on high ozone days; p < 0.05). Thus we conclude that ozone at ambient concentrations initiates a reversible inflammatory response of the upper airways in normal children.