U.C. Davis-Caltrans Air Quality Project, Department of Civil and Environmental Engineering, University of California, Davis, California 95616, USA.
Environ Sci Technol. 2010 Jul 15;44(14):5334-44. doi: 10.1021/es100008x.
Despite increasing regulatory attention and literature linking roadside air pollution to health outcomes, studies on near roadway air quality have not yet been well synthesized. We employ data collected from 1978 as reported in 41 roadside monitoring studies, encompassing more than 700 air pollutant concentration measurements, published as of June 2008. Two types of normalization, background and edge-of-road, were applied to the observed concentrations. Local regression models were specified to the concentration-distance relationship and analysis of variance was used to determine the statistical significance of trends. Using an edge-of-road normalization, almost all pollutants decay to background by 115-570 m from the edge of road; using the more standard background normalization, almost all pollutants decay to background by 160-570 m from the edge of road. Differences between the normalization methods arose due to the likely bias inherent in background normalization, since some reported background values tend to underpredict (be lower than) actual background. Changes in pollutant concentrations with increasing distance from the road fell into one of three groups: at least a 50% decrease in peak/edge-of-road concentration by 150 m, followed by consistent but gradual decay toward background (e.g., carbon monoxide, some ultrafine particulate matter number concentrations); consistent decay or change over the entire distance range (e.g., benzene, nitrogen dioxide); or no trend with distance (e.g., particulate matter mass concentrations).
尽管监管机构越来越重视并将路边空气污染与健康结果联系起来,但对近路空气质 量的研究尚未得到很好的综合。我们使用了截至 2008 年 6 月发表的 41 项路边监测研究中报告的 1978 年收集的数据,其中包括 700 多个空气污染物浓度测量值。对观察到的浓度应用了两种归一化方法,即背景和路边。指定了局部回归模型来拟合浓度-距离关系,并使用方差分析来确定趋势的统计学意义。使用路边归一化,几乎所有污染物在距路边 115-570 米处衰减至背景水平;使用更标准的背景归一化,几乎所有污染物在距路边 160-570 米处衰减至背景水平。归一化方法之间的差异源于背景归一化中固有的可能偏差,因为一些报告的背景值往往低于实际背景。随着与道路距离的增加,污染物浓度的变化分为三类:在 150 米处,峰值/路边浓度至少降低 50%,然后朝着背景持续但逐渐衰减(例如,一氧化碳,一些超细颗粒物数浓度);在整个距离范围内持续衰减或变化(例如,苯,二氧化氮);或无距离趋势(例如,颗粒物质量浓度)。