There is a general consensus that short term exposure to ozone (O 3 ) causes a decrease in lung function parameters such as forced vital capacity (FVC) and forced expiratory volume in one second (FEV1). The objective of this study was to assess the reproducibility of lung function decrements after ambient O 3 exposure over a two-summer period.The authors studied 797 children with a mean age of 8.2 yrs (95% confidence interval: 6.9±9.5) from the second and third grades of ten elementary schools in Austria and southwestern Germany. At the outset the various study locations were stratified into three groups with low (L), medium (M) There was no significant difference in FVC or FEV1 increase between the groups during the winter period. Adjusting for sex, age, height and passive smoke exposure, linear regression revealed a statistically significant negative association of average ambient O 3 concentration with the FVC and FEV1 increase in both summers. During the winter period no association of O 3 with FVC or FEV1 was observed.In conclusion, in two consecutive summer periods the authors found reproducible lung function decrements in children exposed to high levels of ambient ozone. Reoccurrence of ozone associated lung function deficits might increase the likelihood of persisting effects on the childrens' airways. Eur Respir J 2000; 16: 893±900. Laboratory studies of volunteers exposed to high ozone (O 3 ) concentrations in chambers and in epidemiological field studies both have revealed an O 3 related decline in lung function parameters such as forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and peak expiratory flow (PEF) [1±4]. Since children spend more time outdoors and are physically more active than adults and as the growing lung might be more susceptible, they are regarded as a potential risk population for O 3 induced health effects.The authors recently published data from a follow-up study with school-aged children living in two small cities in southwestern Germany [5]. A negative association between O 3 exposure under natural living conditions and lung function (FVC, FEV1) In contrast to the short-term health effects of ozone, there are few studies that have investigated the possible long term health effects of ozone in humans due to problems with exposure assessment and the coincident effects of other pollutants. Reduced levels of FVC and FEV1 after prolonged ozone exposure were reported in both children and adults [15,16]. However, the crosssectional design of these studies does not allow for an investigation into the cause-effect relationship, because outcome as well as exposure is assessed at the same time.Repeated lung-function testing was therefore performed over two years in ten communities with differing levels of Eur Respir J 2000; 16: 893±900 Printed in UK ± all rights reserved
In order to investigate nasal inflammation and subsequent adaptation after ambient ozone exposure, nasal lavage (NL) fluid was collected from 170 schoolchildren on 11 occasions (time points) between March and October.Eosinophil cationic protein (ECP), albumin and leukocytes were quantified as markers of nasal inflammation. The highest half-hour outdoor O 3 concentration for each individual on the day prior to the NL was used as a measure of exposure (O 3 indiv). To avoid confounding with exposure to common environmental allergens, the study population was restricted to children without sensitization to inhalant allergens.In the initial period of increased O 3 levels in May (time point 4), with a median O 3 indiv of 135 mg . m -3 (5th ±95th percentile 100±184 mg . m ). Cross-sectional analysis of all 11 time points revealed no significant association of O 3 indiv on the one hand and ECP, albumin and leukocyte levels on the other. A multivariable model estimated using generalized estimating equations showed a statistically significant association of O 3 indiv and leukocytes and ECP as the dependent variable, when time points 1±4 were analysed (p<0.05). In the same model, this association diminished continuously when time points 5±11 were added stepwise, in spite of high O 3 exposure. Not even a tendency towards an O 3 effect could be recognized when time points 1±8 were considered.The results indicate: 1) acute inflammation of the nasal mucosa after the first increase in ambient ozone levels, with 2) a significant dose-dependent increase in leukocyte and eosinophil cationic protein levels, and 3) possible adaptation of the nasal mucosa in spite of constant high levels of ozone exposure in children during the summer season.
Summary.To investigate the effect of natural exposure to ambient ozone over time, a follow-up study of school-aged children was performed in two small towns in southwestern Germany (Freudenstadt and Villingen) between March and October of 1994. Ozone half-hour mean concentrations were measured continuously and pulmonary function was tested in each child on four occasions (April, June, August, and September). To obtain an average short-term ozone effect, we first analyzed the data from the four time points separately and then constructed a model that included all information. During the study period the median (5th to 95th percentile) of all half-hour values of the ozone concentration was 101 µg/m 3 or 50.6 ppb (45-179 µg/m 3 or 22.5-89.8 ppb) in Freudenstadt and 64 µg/m 3 or 32.1 ppb (1 to 140 µg/m 3 or 0.5-70.1 ppb) in Villingen. To assess the effects of an individual ozone exposure we related the highest ozone concentration in the respective 24 hours before lung function testing to the results of the subsequent pulmonary function tests. In the lung function test following the highest ozone exposure, the results of our cross-sectional linear regression analysis showed a significant negative correlation (P = 0.0181) between ozone exposure and forced vital capacity (FVC). In the longitudinal linear regression model we observed a negative statistical correlation between ozone exposure and lung function for the subpopulation living in the town with the high ozone levels (Freudenstadt). The association was more pronounced in boys than girls. For the children in Freudenstadt the decrement of FVC was −12.31 ml/10 µg/m 3 ozone and the decrease in the forced expiratory volume in 1 second (FEV 1 ) was −11.29 ml/10 µg/m 3 ozone. Pediatr. Pulmonol. 1997; 23:344-353.
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