Harvard School of Public Health, Boston, Massachusetts; State University of New York at Buffalo, Buffalo, New York

Air Toxics Exposure from Vehicular Emissions at a US Border Crossing

Spengler JD, Lwebuga-Mukasa JS

The Peace Bridge Port of Entry into the United States from Canada is the setting for a study assessing exposures to air toxics arising from vehicular emissions. The Peace Bridge Complex consists of the custom station, truck parking area, toll booths, duty-free shop and bridge. Vehicular emissions are of particular concern at border crossings because private and commercial vehicles may idle for considerable time while awaiting border inspection. A pilot study was recently completed in January 2005 which evaluated the feasibility of characterizing the air quality of West Buffalo, a neighborhood lying in the shadow of the Peace Bridge. On average, roughly 4,000 diesel trucks and 14,000 passenger cars cross the bridge each day. With an expansion proposal of the bridge underway, local residents are concerned that this may negatively affect children in the neighborhood who on the whole already have high rate of asthma. This study area can be considered a “hot spot” in that the predominant wind direction is southwesterly with an average wind speed of 12 mph bringing relatively clean air from over Lake Erie before encountering the traffic emissions from the Peace Bridge Complex and subsequently the neighborhood study area which is approximately 1 km2. The pilot study’s objective was to field test the sampling plan and methods, train staff, and determine ambient levels for the various toxins. The pilot consisted of a summer (June 20-26, 2004) and a winter monitoring component (January 8-18, 2005). Descriptive statistics of upwind and downwind concentrations of certain key toxins are presented in the poster. Our sampling plan combined fixed sites containing both integrated and continuous monitors, and mobilized continuous monitors. We were able verify that our sampling methods were adequate to detect all toxins of interest. A consolidated listing of targeted toxins include: PM2.5, ultrafines, black carbon, elements (arsenic, cadmium, chromium, lead, manganese, nickel), nitrogen oxide, carbon monoxide, ozone, VOCs (benzene, 1,3- butadiene, MTBE, toluene, xylene, actetaldehyde, formaldehyde, acrolein), and semi-VOCs (PAHs and nitro-PAHs). Our hypothesis was that the vehicle emissions from the Peace Bridge Complex produce a measurable gradient downwind into the community and embedded within this gradient are a pattern of local sources from the neighborhood street grid. Simply stated, the differences we expected to measure across the study area would depend on a combination of distance from the Peace Bridge Complex, local MET, and the local traffic intensity, composition and spatial pattern. Using a geoadditive spatial model and GIS software, we found that the Peace Bridge Complex does produce a distinct gradient with respect to particle count of PM2.5. We expect this to hold for particle-bound polyaromatic hydrocarbons (PAHs) as measured using a handheld photoelectric aerosol sensor during the winter pilot along with an ultrafine particle counter and handheld GPS. Beyond local health concerns, the findings and methods implemented in the proposed study should be relevant to other similar mobile-source hot spots, such as those along the U.S. borders with Mexico, and other locations of intense vehicle traffic, such as ports.