AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Spatial Variation of Pollutants in the Near-Road Environment
NICHOLE BALDWIN, Philip K. Hopke, Stuart Batterman, Suresh Raja, Clarkson University
Abstract Number: 163 Working Group: Urban Aerosols
Abstract Exposure to traffic-related air pollutants such as black carbon (BC), fine particulate matter (PM2.5), and NO2 can exacerbate asthma and other respiratory problems. Cities such as Detroit, MI have high volumes of local traffic combined with long-haul trucking which contribute to air pollution and thus, respiratory problems of nearby residents. Of particular interest are diesel engine emissions, which consist of ultrafine particles (UFP) that are deposited in the lungs and aggravate disease.
To assess exposure in the vicinity of major roadways, this study aims to characterize pollutant evolution in the near-road environment with respect to time and distance from highways. Sites at varying distances from Detroit highways were sampled for 5 minutes each during mornings and afternoons for 7 consecutive days in two seasons. The concentrations of BC, UFP, PM2.5, PM10, SO2, and NOx were measured. Concentration differences due to time of day, day of the week, distance from highway, wind speed and direction, and season were studied.
Concentrations decreased with distance from the highway with NO and BC showing the largest changes; PM10 changed the least. NO levels decreased 53%, from 25 ppb at 50 m from the highway to 12 ppb at 500 m. BC concentrations decreased 25%. UFP diameters increased from 49 nm to 55 nm. Pollutant levels were usually highest in the morning, a result of meteorological conditions, e.g., diminished dispersion and lower mixing heights. Concentrations at locations 50 and 150 m downwind of highways were usually elevated relative to upwind locations and approached background levels at 500 m downwind.
Traffic-related air pollutant concentrations decrease with distance from highways, thus, people living or working closest to highways receive the highest pollutant exposures. Further analysis of the spatial variation will allow an improved understanding of exposure, advancing health impact assessments.