Environmental Health Sciences Graduate Program, Susan and Henry Samueli College of Health Sciences, University of California, Irvine, CA, USA.
Program in Public Health, Susan and Henry Samueli College of Health Sciences, University of California, Irvine, 653 E. Peltason Dr., AIRB 2042, Irvine, CA, 92697-3957, USA.
Environ Health. 2018 Feb 21;17(1):20. doi: 10.1186/s12940-018-0361-6.
Associations between ambient particulate matter < 2.5 μm (PM) and asthma morbidity have been suggested in previous epidemiologic studies but results are inconsistent for areas with lower PM levels. We estimated the associations between early-life short-term PM exposure and the risk of asthma or wheeze clinical encounters among Massachusetts children in the innovative Pregnancy to Early Life Longitudinal (PELL) cohort data linkage system.
We used a semi-bidirectional case-crossover study design with short-term exposure lags for asthma exacerbation using data from the PELL system. Cases included children up to 9 years of age who had a hospitalization, observational stay, or emergency department visit for asthma or wheeze between January 2001 and September 2009 (n = 33,387). Daily PM concentrations were estimated at a 4-km resolution using satellite remote sensing, land use, and meteorological data. We applied conditional logistic regression models to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CI). We also stratified by potential effect modifiers.
The median PM concentration among participants was 7.8 μg/m with an interquartile range of 5.9 μg/m. Overall, associations between PM exposure and asthma clinical encounters among children at lags 0, 1 and 2 were close to the null value of OR = 1.0. Evidence of effect modification was observed by birthweight for lags 0, 1 and 2 (p < 0.05), and season of clinical encounter for lags 0 and 1 (p < 0.05). Children with low birthweight (LBW) (< 2500 g) had increased odds of having an asthma clinical encounter due to higher PM exposure for lag 1 (OR: 1.08 per interquartile range (IQR) increase in PM; 95% CI: 1.01, 1.15).
Asthma or wheeze exacerbations among LBW children were associated with short-term increases in PM concentrations at low levels in Massachusetts.
先前的流行病学研究表明，环境中直径小于 2.5 微米的颗粒物（PM）与哮喘发病率之间存在关联，但对于 PM 水平较低的地区，结果并不一致。我们利用马萨诸塞州创新妊娠至生命早期纵向（PELL）队列数据链接系统中的数据，估计了生命早期短期 PM 暴露与儿童哮喘或喘息临床就诊风险之间的关联。
我们使用了一种半双向病例交叉研究设计，使用 PELL 系统中的短期暴露滞后来研究哮喘加重的情况。病例包括 2001 年 1 月至 2009 年 9 月期间，0-9 岁儿童因哮喘或喘息住院、观察性住院或急诊就诊（n=33387）。利用卫星遥感、土地利用和气象数据，以 4 公里的分辨率估算 PM 浓度。我们应用条件逻辑回归模型来估计调整后的比值比（OR）和 95%置信区间（CI）。我们还按潜在的效应修饰剂进行分层。
参与者的 PM 浓度中位数为 7.8μg/m，四分位距为 5.9μg/m。总体而言，PM 暴露与儿童滞后 0、1 和 2 时的哮喘临床就诊之间的关联接近 OR=1.0 的零值。在滞后 0、1 和 2 时观察到出生体重的效应修饰，在滞后 0 和 1 时观察到临床就诊季节的效应修饰（p<0.05）。低出生体重（LBW）（<2500g）的儿童由于 PM 暴露增加，因滞后 1 的哮喘临床就诊的几率增加（OR：PM 每四分位距增加 1.08；95%CI：1.01，1.15）。
马萨诸塞州低水平的短期 PM 浓度增加与 LBW 儿童的哮喘或喘息恶化有关。
