From the aDepartment of Epidemiology, University of North Carolina, Chapel Hill, NC; bHealth Sciences Library, University of North Carolina, Chapel Hill, NC; cUnited States Environmental Protection Agency, Research Triangle Park, Durham, NC; dDepartment of Public Health Sciences, Pennsylvania State University, Hershey, PA; eStatistical and Mathematical Sciences Institute, Research Triangle Park, Durham, NC; fDepartment of Statistics and Operations Research, University of North Carolina, Chapel Hill, NC; and gDepartment of Medicine, University of North Carolina, Chapel Hill, NC.
Epidemiology. 2014 Jan;25(1):35-43. doi: 10.1097/EDE.0000000000000006.
Although ambient concentrations of particulate matter ≤10 μm (PM10) are often used as proxies for total personal exposure, correlation (r) between ambient and personal PM10 concentrations varies. Factors underlying this variation and its effect on health outcome-PM exposure relationships remain poorly understood.
We conducted a random-effects meta-analysis to estimate effects of study, participant, and environmental factors on r; used the estimates to impute personal exposure from ambient PM10 concentrations among 4,012 nonsmoking, participants with diabetes in the Women's Health Initiative clinical trial; and then estimated the associations of ambient and imputed personal PM10 concentrations with electrocardiographic measures, such as heart rate variability.
We identified 15 studies (in years 1990-2009) of 342 participants in five countries. The median r was 0.46 (range = 0.13 to 0.72). There was little evidence of funnel plot asymmetry but substantial heterogeneity of r, which increased 0.05 (95% confidence interval = 0.01 to 0.09) per 10 µg/m increase in mean ambient PM10 concentration. Substituting imputed personal exposure for ambient PM10 concentrations shifted mean percent changes in electrocardiographic measures per 10 µg/m increase in exposure away from the null and decreased their precision, for example, -2.0% (-4.6% to 0.7%) versus -7.9% (-15.9% to 0.9%), for the standard deviation of normal-to-normal RR interval duration.
Analogous distributions and heterogeneity of r in extant meta-analyses of ambient and personal PM2.5 concentrations suggest that observed shifts in mean percent change and decreases in precision may be generalizable across particle size.
虽然环境中 PM10（颗粒物小于等于 10 微米）浓度通常被用作总个人暴露的替代物，但环境和个人 PM10 浓度之间的相关性（r）存在差异。导致这种差异的因素及其对健康结果-暴露关系的影响仍知之甚少。
我们进行了一项随机效应荟萃分析，以估计研究、参与者和环境因素对 r 的影响；利用这些估计值，从妇女健康倡议临床试验中的 4012 名非吸烟、患有糖尿病的参与者中推断出个人的环境 PM10 暴露量；然后估计环境和推断的个人 PM10 浓度与心电图测量值（如心率变异性）之间的关联。
我们确定了 15 项研究（1990-2009 年），涉及五个国家的 342 名参与者。中位数 r 为 0.46（范围为 0.13 至 0.72）。虽然漏斗图不对称的证据很少，但 r 的异质性很大，平均环境 PM10 浓度每增加 10 µg/m，r 增加 0.05（95%置信区间为 0.01 至 0.09）。用推断的个人暴露量替代环境 PM10 浓度会使暴露量每增加 10 µg/m 时心电图测量值的平均百分比变化偏离零值，并降低其精度，例如，正常到正常 RR 间隔持续时间的标准偏差从-2.0%（-4.6%至 0.7%）变为-7.9%（-15.9%至 0.9%）。
在对环境和个人 PM2.5 浓度进行的现有荟萃分析中，r 的分布和异质性类似，这表明观察到的平均百分比变化的变化和精度的降低可能在颗粒尺寸上具有普遍性。
