AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
An Annual Study of Chemical Composition and Source Apportionment of Ultrafine Particulate Matter (PM0.1) in Three Major Cities in California
JIAN XUE, Wei Xue, Michael Kleeman, University of California, Davis
Abstract Number: 556 Working Group: Urban Aerosols
Abstract Numerous studies have identified associations between the mass of particles with aerodynamic diameter < 2.5 µm (PM$_(2.5)) and premature mortality but far less is known about the public health threat associated with smaller particle size fractions within the PM2.5 metric. One size range of great interest is ultrafine particles (UFPs, PM$_(0.1), Dp < 0.1 µm) due to the ability of these particles to access to the blood circulation and translocate to different regions of the body, and their apparent toxicity in multiple studies. The present work is the first stage of a framework study to perform a state-of-the-science exposure assessment for UFPs and to determine if UFPs are positively associated with premature death in California.
A sampling network was deployed across 3 polluted California cities for 1 year (2015/2016) to measure the concentration and composition of UFPs. Two stations are located in the San Francisco Bay Area, one station is located in Fresno, and one station is located in Los Angeles. UFPs samples were collected with 3 day averaging times using Micro Orifice Uniform Deposit Impactors (MOUDIs). Two impactors were deployed at each site to support a full range of chemical analysis. The first MOUDI was loaded with aluminum foil substrates prebaked at 550oC for characterization of carbonaceous material. The second MOUDI was loaded with Teflon substrates for characterization of trace elements. The chemical concentrations across the year were input to the Positive Matrix Factorization (PMF) model to identify UFPs source contributions from diesel engines, gasoline engines, brake wear/road dust, rail, residential wood burning, and food cooking. The results reveal interesting trends in the annual variation of UFPs chemical composition, spatial gradients, atmospheric processing, and source contributions. The results will provide a basis for future comparison to exposure estimates produced by regional chemical transport models and evaluation of future control strategies.