Wilson William E, Brauer Michael
National Center for Environmental Assessment, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA.
J Expo Sci Environ Epidemiol. 2006 May;16(3):264-74. doi: 10.1038/sj.jes.7500483.
To provide additional insight into factors affecting exposure to airborne particulate matter and the resultant health effects, we developed a method to estimate the ambient and nonambient components of total personal exposure. The ambient (or outdoor) component of total personal exposure to particulate matter (PM) (called ambient exposure) includes exposure to the ambient PM concentration while outdoors and exposure while indoors to ambient PM that has infiltrated indoors. The nonambient component of total personal exposure to PM (called nonambient exposure) refers to exposure to PM generated by indoor sources and an individual's personal activity. We used data collected from a personal monitoring study in Vancouver, Canada to demonstrate the methodology. In this study, ambient PM(2.5) exposure was 71% of the measured ambient PM(2.5) concentration and was responsible for 44% of the measured total personal PM(2.5) exposure. Regression analysis of the pooled data sets for ambient and total exposure against outdoor concentrations yielded similar slopes (0.76 for ambient and 0.77 for total) but a higher coefficient of determination for ambient exposure (R(2)=0.62) than for total exposure (R(2)=0.072). As expected, the nonambient exposure was not related to the ambient concentration (R(2)<10(-6)). For longitudinal analyses of the relationship between measured personal exposure and ambient concentrations for individual subjects, the correlation of total personal exposure with ambient concentration yielded values of Pearson's r from 0.83 to -0.68 with an average of 0.36. The relationship was statistically significant for only five of the 16 subjects. In contrast, the correlation of the estimated ambient exposure with ambient concentration yielded values of Pearson's r from 0.92 to 0.77 with an average of 0.88; 14 were significant. An example, taken from an epidemiologic analysis using the exposure data from this paper, demonstrates the usefulness of separating total exposure into its ambient and nonambient components.
为了更深入地了解影响空气中颗粒物暴露及其对健康影响的因素，我们开发了一种方法来估算个人总暴露中的环境和非环境成分。个人对颗粒物（PM）总暴露的环境（或室外）成分（称为环境暴露）包括在室外时对环境PM浓度的暴露以及在室内时对渗入室内的环境PM的暴露。个人对PM总暴露的非环境成分（称为非环境暴露）是指对室内源产生的PM以及个人自身活动产生的PM的暴露。我们使用从加拿大温哥华的一项个人监测研究中收集的数据来演示该方法。在这项研究中，环境PM（2.5）暴露占测量的环境PM（2.5）浓度的71%，并占测量的个人总PM（2.5）暴露的44%。对环境暴露和总暴露的合并数据集与室外浓度进行回归分析，得到了相似的斜率（环境暴露为0.76，总暴露为0.77），但环境暴露的决定系数（R² = 0.62）高于总暴露的决定系数（R² = 0.072）。正如预期的那样，非环境暴露与环境浓度无关（R² < 10⁻⁶）。对于个体受试者测量的个人暴露与环境浓度之间关系的纵向分析，个人总暴露与环境浓度的相关性产生的Pearson's r值范围为0.83至 -0.68，平均值为0.36。在16名受试者中，只有5名受试者的这种关系具有统计学意义。相比之下，估计的环境暴露与环境浓度的相关性产生的Pearson's r值范围为0.92至0.77，平均值为0.88；其中14个具有统计学意义。本文通过一项使用暴露数据的流行病学分析实例，展示了将总暴露分为环境和非环境成分的有用性。
