AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
In-situ Measurements of Particle Size and Volatility in a Traffic Tunnel
ALBERT A. PRESTO, Xiang Li, Carnegie Mellon University
Abstract Number: 131 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract Motor vehicles are an important source of gas- and particle-phase pollutants to the atmosphere. Emissions from motor vehicles include CO, NOx, volatile organic compounds (VOCs), and particulate matter (PM). Direct PM emissions from vehicles are dominated by the carbonaceous fraction in the form of organic aerosol (OA) and carbon soot (EC/BC). These PM emissions are dominated by ultrafine particles (diameters smaller than 100 nm).
Emissions from vehicular sources can be measured with dynamometer studies, near-road or on-road measurements, and tunnel studies. Tunnel studies hold the unique advantage that primary emissions are largely captive, with minimal mixing from outside air. This poster presents measurements of particle and gas-phase pollutant concentrations from a traffic tunnel in Pittsburgh, PA. Gas-phase measurements include NOx, CO, and CO2. Particle-phase measurements include OC and EC, as measured with an in situ Sunset OC/EC analyzer, black carbon (single particle soot photometer), and particle size distributions (scanning mobility particle sizer). Particles were also sampled through a thermodenuder operating at 60, 80, and 100o C.
The measurements are used to determine emission factors as a function of season, traffic volume, and vehicle fleet composition. Thermodenuder data are used to assess the volatility of primary PM emissions, particularly the OA fraction. Results will be compared to data collected in a recent series of dynamometer test conducted by this group in conjunction with the CA Air Resources Board.