Meta-Analysis on Near-Road Air Pollutants Concentrations for Developing Traffic Indicators for Exposure Assessment

摘要

Near-road air pollution has been associated with various health risks in human populations living near roadways. To better understand relationship between vehicle emissions and spatial profiles of traffic-related air pollutants we performed a comprehensive and systematic literature survey on publications containing measurement data for air pollutants with distance information from roads. 8169 publications matched to the initial wide-scope keywords search and 3799 publications were retained after excluding publications related to models, health effects, and land use. 1879 publications were collected into an Endnote library after screening the 3799 publications for containing information on black carbon (BC), carbon monoxide (CO), nitrogen oxides (NO, NO2, or NOx), and particulate matter (PM). Three researchers independently read the abstracts of these 1879 publications to find those containing actual data for the selected air pollutants near major roads with distance profiles. Analyses were performed on concentration data of the selected air pollutants from 65 publications meeting the final criteria. These analyses showed no apparent distance decay relationship for PM but a clear distance-decay for BC. NOx also showed distance gradients which are more obvious than that shown for CO. These initial observations suggest that some near-road air pollutants bear closer relationship with the vehicle emissions than the others. Further analysis of original data obtained from EPA near-road study projects will refine these spatial-distance-decay patterns. Thus it is possible to develop traffic density-defined parameters for serving as surrogate pollution indexes for these air pollutants.