AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Effects of Diesel Particle Filters on the Size Distribution of Emitted Particles
CHELSEA PREBLE, Nicholas Tang, Timothy Dallmann, Nathan Kreisberg, Susanne Hering, Robert Harley, Thomas Kirchstetter, University of California, Berkeley
Abstract Number: 704 Working Group: Urban Aerosols
Abstract Diesel particle filters (DPFs) reduce the mass of particles emitted from diesel trucks. However, there may be some unintended consequences of using these filters, such as a concomitant increase in emission of ultrafine particles (UFPs). UFPs are not specifically regulated by current air quality standards but they may pose a health risk that larger particles do not because of their small size (< 100 nm in diameter).
The present study measured pollutants emitted from trucks at the Port of Oakland, California in November 2011. At this location, the California Air Resources Board’s Drayage Truck Regulation required replacement of trucks with pre-1994 engines and retrofit with diesel particulate filters (DPFs) of trucks with newer engines. The size distribution of particles in the exhaust plumes of individual heavy-duty trucks en route to the Port were measured at a frequency of 1 Hz using a Fast Mobility Particle Sizer (FMPS, TSI model 3091). Emissions were linked on a truck-by-truck basis to installed emission control equipment via the matching of transcribed license plates to a Port truck database.
This analysis examines particle size distributions in the exhaust of trucks (1) retrofitted with DPFs, (2) equipped with DPFs as original equipment, and (3) not equipped with DPFs. Preliminary findings indicate that (a) most trucks emitted particles characterized by a single mode of approximately 100 nm in diameter and (b) new trucks originally equipped with DPFs were 5 to 6 times more likely than DPF-retrofitted trucks and trucks without DPFs to emit particles characterized by a single mode in the range of 10 to 30 nm in diameter. This analysis also indicated a sampling artifact of the FMPS, which overstates the presence of ultrafine particles on the trailing side of a peak when concentrations are rapidly decreasing.