Fine Particle Emissions from Light Duty Vehicles: Gas-Particle Partitioning of Primary Organic Aerosol and Secondary Organic Aerosol Formation

ALBERT PRESTO (1), Timothy Gordon (1,2), Ngoc Nguyen (1,3), Andrew May (1,3), Chris Hennigan (1,3), Allen Robinson (1,2,3), Hector Maldonado (4), Sulekha Chattopadhyay (4), Alvaro Gutierrez (4), Matti Maricq (5), Eric Lipsky (6)

(1) Center for Particle Studies, Carnegie Mellon University, (2) Engineering and Public Policy, Carnegie Mellon University, (3) Mechanical Engineering, Carnegie Mellon University, (4) California Air Resources Board, (5) Ford Motor Company, (6) Pennsylvania State University, Greater Allegheny

     Abstract Number: 511
     Last modified: May 13, 2010

Abstract
Emissions from motor vehicles are a major contributor to fine particle pollution in urban environments. Experiments were conducted at the California Haagen-Smit Laboratory to investigate fine particle emissions from light duty vehicles. Separate tests were performed using more than 50 vehicles recruited from the in-use California fleet operated over the Unified Driving Cycle. The test fleet included a wide range of vehicle types (car, light duty truck, SUV), model years (1990-2009), emission control technologies and fuels (gasoline, biodiesel (B100), ULSD).

The gas- and particulate-phase emissions from every vehicle were characterized by collecting samples from a constant volume sampling system. Tenax sorbent samples were collected to characterize the emissions of semivolatile and intermediate volatility organic compounds. For select vehicles, the emissions were also injected into a smog chamber and then photochemically aged. Experiments with seed aerosols and a thermodenuder were used to characterize the gas-particle partitioning of the primary organic aerosols. Data from the smog chamber experiments were used to quantify the secondary organic aerosol (SOA) production from the different vehicle/fuel combinations. Smog chamber experiments were conducted at different VOC to NOx ratios (representative of the range of atmospheric conditions from urban to rural locations) to quantify the impact of this variable on SOA emission factors. The measured secondary aerosol production is being compared to predictions from a SOAM II model. This presentation will highlight the initial results from this large test campaign.