AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Ultrafine Particle Exposure of Street Users Walking, Cycling, and Driving Along an Urban Residential Roadway
DAVID QUIROS, Eon Lee, Yifang Zhu, Rui Wang, University of California, Los Angeles
Abstract Number: 285 Working Group: Urban Aerosols
Abstract Elevated concentrations of ultrafine particles (UFPs, < 0.1 micro-meters), which have been linked to adverse health effects, are commonly found near roadways. We measured particle number concentration (PNC) across three transportation modes on an urban residential street in Santa Monica, CA: walking, cycling, and driving with windows open and windows closed. We repeated measurements concurrently for nine days during the morning (7:30-9:00), afternoon (12:30-14:00), and evening (17:00-18:00). We observed ~60% PNC reductions when driving with closed with recirculation, relative to modes with direct contact to the outside air (cycling, walking, and driving with windows open). Afternoon and evening period PNC was ~75% lower than morning period PNC. We found nearly four times higher exposure to commuters cycling and walking due to higher ventilation rates and longer durations per round trip. We found positive associations between PNC and road grade and proximity to intersections. We classified on-roadway fleet by vehicle type from video recorded footage, and found our measured PNC originated ~30% from older (before 1980) gasoline vehicles, ~40% from newer gasoline vehicles, and ~30% from diesel trucks (school buses, garbage trucks, and heavy-duty diesel trucks). This is one of the first transportation mode comparison studies in the United States for assessment of commuter exposure to UFPs and other air pollutants. The study site is currently under redesign construction and when completed will meet the California Complete Streets Act standards. Our study serves as a baseline condition for UFP exposure across all street users.