BACKGROUND Ambient and home exposure to nitrogen dioxide (NO2) causes asthma symptoms and decreased lung function in children with asthma. Little is known about the health effects of school classroom pollution exposure. OBJECTIVE We aimed to determine the effect of indoor classroom NO2 on lung function and symptoms in inner-city school children with asthma. METHODS Children enrolled in the School Inner-City Asthma Study were followed for 1 academic year. Subjects performed spirometry and had fraction of exhaled nitric oxide values measured twice during the school year at school. Classroom NO2 was collected by means of passive sampling for 1-week periods twice per year, coinciding with lung function testing. Generalized estimating equation models assessed lung function and symptom relationships with the temporally nearest classroom NO2 level. RESULTS The mean NO2 value was 11.1 ppb (range, 4.3-29.7 ppb). In total, exposure data were available for 296 subjects, 188 of whom had complete spirometric data. At greater than a threshold of 8 ppb of NO2 and after adjusting for race and season (spirometry standardized by age, height, and sex), NO2 levels were associated highly with airflow obstruction, such that each 10-ppb increase in NO2 level was associated with a 5% decrease in FEV1/forced vital capacity ratio (β = -0.05; 95% CI, -0.08 to -0.02; P = .01). Percent predicted forced expiratory flow between the 25th and 75th percentile of forced vital capacity was also inversely associated with higher NO2 exposure (β = -22.8; 95% CI, -36.0 to -9.7; P = .01). There was no significant association of NO2 levels with percent predicted FEV1, fraction of exhaled nitric oxide, or asthma symptoms. Additionally, there was no effect modification of atopy on lung function or symptom outcomes. CONCLUSION In children with asthma, indoor classroom NO2 levels can be associated with increased airflow obstruction.

中文翻译：

---

内城区哮喘儿童学校教室中的二氧化氮暴露量。

背景技术环境和家庭中暴露于二氧化氮（NO2）会导致哮喘症状，并使哮喘患儿的肺功能下降。关于学校教室污染暴露对健康的影响知之甚少。目的我们旨在确定室内教室NO2对内城区小学生哮喘的肺功能和症状的影响。方法对参加学校城市哮喘研究的儿童进行为期1个学年的随访。受试者进行肺活量测定，并在学年中两次测量呼出一氧化氮的分数。每年两次通过被动采样的方式收集教室NO2，为期1周，每年两次，与肺功能测试相吻合。广义估计方程模型评估与暂时性教室NO2水平之间的肺功能和症状关系。结果NO2平均值为11.1 ppb（范围4.3-29.7 ppb）。总共有296位受试者的暴露数据，其中188位具有完整的肺活量测定数据。当NO2的阈值大于8 ppb时，并根据种族和季节进行了调整（通过年龄，身高和性别标准化的肺活量测定），NO2的水平与气流阻塞高度相关，因此，每升高10 ppb的NO2水平都与之相关。 FEV1 /强迫肺活量比降低了5％（β= -0.05； 95％CI，-0.08至-0.02； P = 0.01）。强迫肺活量的第25至第75个百分位之间的预计强迫呼气流量百分比也与较高的NO2暴露呈负相关（β= -22.8； 95％CI，-36.0至-9.7； P = 0.01）。NO 2水平与预测的FEV 1百分比，呼出的一氧化氮分数或哮喘症状之间无显着相关性。另外，特应性对肺功能或症状结局没有影响。结论在哮喘儿童中，室内教室NO2水平可能与气流阻塞增加有关。