Personally measured weekly exposure to NO2 and respiratory health among preschool children

Nitrogen dioxide is known as a deep lung irritant. The aim of this study wa s to find out whether the relatively low ambient air NO2 concentrations in the northern city of Helsinki had an impact on the respiratory health of ch ildren. The association between personal exposure to ambient air NO2 and respirator y health was investigated in a 13-week follow-up study among 163 preschool children aged 3-6 yrs, Personal weekly average exposure to NO2 was measured by passive diffusion samplers attached to the outer garments, Symptoms wer e recorded daily in a diary by the parents, Among 53 children, peak expirat ory flow (PEF) was measured at home in the mornings and evenings. The assoc iation between NO2 exposure and respiratory symptoms was examined with Pois son regression. The median personal NO2 exposure was 21.1 mu g.m(-3) (range 4-99 mu g.m(-3) . An increased risk of cough was associated with increasing NO2 exposure (r isk ratio=1.52; 95% confidence interval 1.00-2.31). There was no such assoc iation between personal weekly NO2 exposure and nasal symptoms, but a nonsi gnificant negative association was found between the exposure and the weekl y average deviation in PEF. In conclusion, even low ambient air NO2 concentrations can increase the ris k of respiratory symptoms among preschool children.