EXHALED NO IN CHILDREN EXPOSED TO OZONE 125 INCREASE OF EXHALED NITRIC OXIDE IN CHILDREN EXPOSED TO LOW LEVELS OF AMBIENT OZONE

Ozone (O3) is known to induce lung function impairment and airways inflammation during episodes of photochemical smog. The aim of the present study was to assess the inflammatory effect of ambient O3 in healthy children using nitric oxide in exhaled air (eNO) as a non invasive test. The study was performed on six groups of children (n = 11-15), aged 6.5 to 15 years who attended summer camps in rural areas of the South of Belgium in 2002. Ambient O3 concentrations continuously monitored in the camps ranged from 48 to 221 µg/m3 (1-hour maximal concentration). Children remained outdoors during the experimental days doing various recreational activities but no sports. Lung function tests (FEV1 and FVC) and eNO were measured twice in each child in the morning and in the evening. Whilst lung function tests did not show any consistent pattern of decrease at these O3 levels, a highly significant increase in eNO was found in all subjects from an ambient 1-hour O3 level of 167 µg/m3. A multivariate analysis did not reveal any influence of age, gender, height, weight and BMI of the children. The threshold for this O3-induced increase in eNO estimated benchmark dose analysis was 135 µg/m3 for 1-hour exposure and 110 µg/m3 for 8-hour exposure. These observations suggest that ambient ozone produces early inflammatory changes in the airways of children from levels slightly below current air quality standards