title: Spatial and temporal differences in traffic-related air pollution in three urban neighborhoods near an interstate highway.
abstract: Relatively few studies have characterized differences in intra- and inter-neighborhood traffic-related air pollutant (TRAP) concentrations and distance-decay gradients in along an urban highway for the purposes of exposure assessment. The goal of this work was to determine the extent to which intra- and inter-neighborhood differences in TRAP concentrations can be explained by traffic and meteorology in three pairs of neighborhoods along Interstate 93 (I-93) in the metropolitan Boston area (USA). We measured distance-decay gradients of seven TRAPs (PNC, pPAH, NO, NOX, BC, CO, PM2.5) in near-highway (<400 m) and background areas (>1 km) in Somerville, Dorchester/South Boston, Chinatown and Malden to determine whether (1) spatial patterns in concentrations and inter-pollutant correlations differ between neighborhoods, and (2) variation within and between neighborhoods can be explained by traffic and meteorology. The neighborhoods ranged in area from 0.5 to 2.3 km2. Mobile monitoring was performed over the course of one year in each pair of neighborhoods (one pair of neighborhoods per year in three successive years; 35-47 days of monitoring in each neighborhood). Pollutant levels generally increased with highway proximity, consistent with I-93 being a major source of TRAP; however, the slope and extent of the distance-decay gradients varied by neighborhood as well as by pollutant, season and time of day. Correlations among pollutants differed between neighborhoods (e.g., ρ = 0.35-0.80 between PNC and NOXand ρ = 0.11-0.60 between PNC and BC) and were generally lower in Dorchester/South Boston than in the other neighborhoods. We found that the generalizability of near-road gradients and near-highway/urban background contrasts was limited for near-highway neighborhoods in a metropolitan area with substantial local street traffic. Our findings illustrate the importance of measuring gradients of multiple pollutants under different ambient conditions in individual near-highway neighborhoods for health studies involving inter-neighborhood comparisons.
authors.affiliation: Civil and Environmental Engineering, Tufts University, 200 College Ave, Medford, MA 02155, USA.
authors.forename: Allison P
authors.initials: AP
authors.lastname: Patton
authors.affiliation: Civil and Environmental Engineering, Tufts University, 200 College Ave, Medford, MA 02155, USA.
authors.forename: Jessica
authors.initials: J
authors.lastname: Perkins
authors.affiliation: Somerville Transportation Equity Partnership, Somerville, MA, USA.
authors.forename: Wig
authors.initials: W
authors.lastname: Zamore
authors.affiliation: Boston University School of Public Health, 715 Albany St, Boston, MA 02118, USA.
authors.forename: Jonathan I
authors.initials: JI
authors.lastname: Levy
authors.affiliation: Public Health and Community Medicine, Tufts University, 136 Harrison Avenue, Boston, MA 02111, USA.
authors.forename: Doug
authors.initials: D
authors.lastname: Brugge
authors.affiliation: Civil and Environmental Engineering, Tufts University, 200 College Ave, Medford, MA 02155, USA.
authors.forename: John L
authors.initials: JL
authors.lastname: Durant
keywords: distance-decay gradients; metropolitan Boston (USA); mobile monitoring; near-highway; traffic-related air pollution