Loftus Christine, Yost Michael, Sampson Paul, Arias Griselda, Torres Elizabeth, Vasquez Victoria Breckwich, Bhatti Parveen, Karr Catherine
Department of Epidemiology, School of Public Health, University of Washington, Box 357236, Seattle, WA 98195, United States.
Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Box 357234, Seattle, WA 98195, United States.
Environ Res. 2015 Jan;136:505-12. doi: 10.1016/j.envres.2014.10.030. Epub 2014 Nov 27.
Elevated pediatric asthma morbidity has been observed in rural US communities, but the role of the ambient environment in exacerbating rural asthma is poorly understood.
To investigate associations between particulate matter less than 2.5 μm in diameter (PM2.5) and pediatric asthma exacerbations in an agricultural community of Washington State.
School-aged children with asthma (n=58) were followed for up to 25 months with repeated measures of respiratory health. Asthma symptoms and quick-relief medication use were assessed biweekly through phone administered surveys (n=2023 interviews). In addition, subjects used home peak flow meters on a daily basis to measure forced expiratory volume in one second (FEV1) (n=7830 measurements). Regional PM2.5 was measured at a single air monitor located centrally in the study region. To assess relationships between PM2.5 and these outcomes we used linear regression with generalized estimating equations, adjusting for meteorological and temporal confounders. Effect modification by atopy was explored as well.
An interquartile increase (IQR) in weekly PM2.5 of 6.7 μg/m(3) was associated with an increase in reported asthma symptoms Specific symptoms including wheezing, limitation of activities, and nighttime waking displayed the strongest associations. FEV1 as a percent of predicted decreased by 0.9% (95%CI: -1.8, 0.0) for an IQR increase in PM2.5 one day prior, and by 1.4% (95%CI: -2.7, -0.2) when restricted to children with atopic asthma.
This study provides evidence that PM2.5 in an agricultural setting contributes to elevated asthma morbidity. Further work on identifying and mitigating sources of PM2.5 in the area is warranted.
美国农村社区儿童哮喘发病率升高，但环境因素在加重农村哮喘方面的作用尚不清楚。
调查华盛顿州一个农业社区中直径小于2.5μm的颗粒物（PM2.5）与儿童哮喘发作之间的关联。
对58名患有哮喘的学龄儿童进行长达25个月的跟踪，重复测量其呼吸健康状况。通过电话调查（共2023次访谈）每两周评估一次哮喘症状和速效药物的使用情况。此外，受试者每天使用家用峰值流量计测量一秒用力呼气量（FEV1）（共7830次测量）。在研究区域中心的一个空气监测站测量区域PM2.5。为了评估PM2.5与这些结果之间的关系，我们使用了带有广义估计方程的线性回归，并对气象和时间混杂因素进行了调整。还探讨了特应性对效应的修饰作用。
每周PM2.5增加一个四分位数间距（IQR），即6.7μg/m³，与报告的哮喘症状增加有关。包括喘息、活动受限和夜间醒来在内的特定症状显示出最强的关联。前一天PM2.5的IQR增加时，FEV1占预测值的百分比下降了0.9%（95%CI：-1.8，0.0），而对于患有特应性哮喘的儿童，这一比例下降了1.4%（95%CI：-2.7，-0.2）。
本研究提供了证据表明农业环境中的PM2.5会导致哮喘发病率升高。有必要进一步开展工作以识别和减轻该地区PM2.5的来源。
