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Physical and Chemical Characterization of Atmospheric Ultrafine Particles in the Los Angeles Area

Hughes, Lara S. and Cass, Glen R. and Gone, Jec and Ames, Michael and Olmez, Ilhan (1998) Physical and Chemical Characterization of Atmospheric Ultrafine Particles in the Los Angeles Area. Environmental Science and Technology, 32 (9). pp. 1153-1161. ISSN 0013-936X. doi:10.1021/es970280r.

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Atmospheric ultrafine particles (diameter < 0.1 μm) are under study by inhalation toxicologists to determine whether they pose a threat to public health, yet, little is known about the chemical composition of ultrafine particles in the atmosphere of cities. In the present work, the number concentration, size distribution, and chemical composition of atmospheric ultrafine particles is determined under wintertime conditions in Pasadena, CA, near Los Angeles. These experiments are conducted using a scanning differential mobility analyzer, laser optical counter, and two micro-orifice impactors. Samples are analyzed to create a material balance on the chemical composition of the ultrafine particles. The number concentration of ultrafine particles in the size range 0.017 < d_p < 0.1 μm, analyzed over 24-h periods, is found to be consistently in the range 1.3 × 10^4 ± 8.9 × 10^3 particles cm^(-3) air. Ultrafine particle mass concentrations are in the range 0.80−1.58 μg m^(-3). Organic compounds are the largest contributors to the ultrafine particle mass concentration. A small amount of sulfate is present in these particles, at concentrations too low to tell whether it exists as unneutralized sulfuric acid. Iron is the most prominent transition metal found in the ultrafine particles. These data may assist the health effects research community in constructing realistic animal or human exposure studies involving ultrafine particles.

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Additional Information:© 1999 American Chemical Society. Received for review March 26, 1997. Revised manuscript received December 18, 1997. Accepted January 6, 1998. This work was supported by the Center for Air Quality Analysis at Caltech. Thanks are due to Drs. Kent Hoekman and Steve Ziman of Chevron for assistance with this research. Aerosol carbon analyses were performed by Bob Cary at Sunset Labs, Forest Grove, OR.
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Caltech Center for Air Quality AnalysisUNSPECIFIED
Issue or Number:9
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Official Citation:Physical and Chemical Characterization of Atmospheric Ultrafine Particles in the Los Angeles Area Lara S. Hughes, Glen R. Cass, Jec Gone, Michael Ames,and Ilhan Olmez Environmental Science & Technology 1998 32 (9), 1153-1161 DOI: 10.1021/es970280r
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:67875
Deposited By: George Porter
Deposited On:13 Jun 2016 20:06
Last Modified:11 Nov 2021 03:56

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