RESPIRATORY EFFECTS ASSOCIATED WITH INDOOR NITROGEN-DIOXIDE EXPOSURE IN CHILDREN

Background. The human health effects of exposure to indoor nitrogen di oxide (NO2) are unclear, and few studies have examined the effects of short-term peak levels of exposure. Methods. The association between i ndoor exposure to NO2 and respiratory illness was examined in 388 chil dren aged 6-11 years. The NO2 levels were monitored during winter in 4 1 classrooms, from four schools with unflued gas heating and four scho ols with electric heating. Each classroom was monitored daily with B-h our passive diffusion badge monitors over nine alternate weeks, and wi th hourly monitors over two of those weeks. Children living in homes w ith unflued gas appliances were also monitored daily over four evening s during times of gas use. Results. Exposure to NO2 at hourly peak lev els of the order of greater than or equal to 80 ppb, compared with bac kground levels of 20 ppb, was associated with a significant increase i n sore throat, colds and absences from school. An increase in cough wi th phlegm was marginally significant. Significant dose-response relati onships were demonstrated for these four measures with increasing leve ls of NO2 exposure. Conclusions. Short-term peak levels of exposure ar e important to consider in relation to adverse respiratory effects ass ociated with NO2 exposure.