Spatial and Temporal Distribution of Near-Highway Air Pollution in Three Urban Neighborhoods in Metropolitan Boston (USA)

摘要

While exposures to components of air pollution vary both within and between neighborhoods, it is unknown to what extent multi-pollutant concentration patterns are generalizable across near-highway neighborhoods in a metropolitan area. The goal of this work was to determine the extent of inter-neighborhood differences that can be explained by different sources, geography, and meteorology in three neighborhoods (Somerville, Dorchester, and Chinatown) along Interstate 93 (I-93) in the metropolitan Boston area (USA). The objectives were to characterize spatial gradients from I-93 and temporally-varying predictors of seven traffic-related air pollutants (PNC, PAH, NO, NO_x, BC, CO, PM_(2.5)) to (1) determine whether spatial patterns in concentrations and inter-pollutant correlations among pollutants differ across neighborhoods; and (2) determine whether variation across neighborhoods can be explained by local sources or meteorology. One year of mobile monitoring (36-55 days per neighborhood) was performed in near-highway (＜400 m) and paired urban background (＞1000 m) neighborhoods. Effects of temperature, wind speed and direction, and highway traffic volume were estimated using mixed effects models. Pollutant levels generally increased with highway proximity, consistent with I-93 as a major source of traffic-related pollution; however, distance-decay gradients varied by pollutant, neighborhood, time of day, and season. Correlations among pollutants differed across neighborhoods (e.g., p = 0.35-0.80 between UFP and NO_x and p = 0.11-0.60 between UFP and BC) and were generally lower in Dorchester than in the other neighborhoods. Examination of concentration patterns indicated contributions from major surface roads that were comparable in magnitude to contributions from I-93. The differences in near-highway pollutant distributions in a single metropolitan area suggest that caution should be used when assuming similarity of near-highway areas for epidemiology studies.