title: The mobile source effect on curbside 1,3-butadiene, benzene, and particle-bound polycyclic aromatic hydrocarbons assessed at a tollbooth.
abstract: On-road mobile sources contribute substantially to ambient air concentrations of the carcinogens 1,3-butadiene, benzene, and polycyclic aromatic hydrocarbons (PAHs). The current study measured benzene and 1,3-butadiene at the Baltimore Harbor Tunnel tollbooth over 3-hr intervals on seven weekdays (n = 56). Particle-bound PAH was measured on a subset of three days. The 3-hr outdoor 1,3-butadiene levels varied according to time of day and traffic volume. The minimum occurred at night (12 a.m.-3 a.m.) with a mean of 2 microg/m3 (SD = 1.3, n = 7), while the maximum occurred during the morning rush hour (6 a.m.-9 a.m.) with a mean of 11.9 microg/m3 (SD = 4.6, n = 7). The corresponding traffic counts were 1413 (SD = 144) and 16,893 (SD = 692), respectively. During the same intervals, mean benzene concentration varied from 3 microg/m3 (SD = 3.1, n = 7) to 22.3 microg/m3 (SD = 7.6, n = 7). Median PAH concentrations ranged from 9 to 199 ng/m3. Using multivariate regression, a significant association (p < 0.001) between traffic and curbside concentration was observed. Much of the pollutant variability (1,3-butadiene 62%, benzene 77%, and PAH 85%) was explained by traffic volume, class, and meteorology. Results suggest > 2-axle vehicles emit 60, 32, and 9 times more PAH, 1,3-butadiene, and benzene, respectively, than do 2-axle vehicles. This study provides a model for estimating curbside pollution levels associated with traffic that may be relevant to exposures in the urban environment.
authors.affiliation: Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21205, USA. asapkota@jhsph.edu
authors.forename: Amir
authors.initials: A
authors.lastname: Sapkota
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Buckley
mesh_terms: D000465:Algorithms; D001554:Benzene / Q000032:analysis*; D002070:Butadienes / Q000032:analysis*; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000032:analysis*; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis*; D014481:United States; D014484:United States Environmental Protection Agency
chemical_list: D002070:Butadienes; D004785:Environmental Pollutants; D011084:Polycyclic Aromatic Hydrocarbons; D001554:Benzene; C031763:1,3-butadiene