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Development and Evaluation of a Continuous Coarse (PM10-PM2.5) Particle Monitor

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Abstract: In this paper, we describe the development and laboratory and field evaluation of a continuous coarse (2.5-10 um) particle mass (PM) monitor that can provide reliable measurements of the coarse mass (CM) concentrations in time intervals as short as 5-10 min. The operating principle of the monitor is based on enriching CM concentrations by a factor of -25 by means of a 2.5-um cut point round nozzle virtual impactor while maintaining fine mass (FM) - that is, the mass of PM2.5 at ambient concentrations. The aerosol mixture is subsequently drawn through a standard tapered element oscillating microbalance (TEOM), the response of which is dominated by the contributions of the CM, due to concentration enrichment. Findings from the field study ascertain that a TEOM coupled with a PM10 inlet followed by a 2.5-um cut point round nozzle virtual impactor can be used successfully for continuous CM concentration measurements. The average concentration-enriched CM concentrations measured by the TEOM were 26-27 times higher than those measured by the time-integrated PM 10 samplers [the micro-orifice uniform deposit impactor (MOUDI) and the Partisol] and were highly correlated. CM concentrations measured by the concentration-enriched TEOM were independent of the ambient FM-to-CM concentration ratio, due to the decrease in ambient coarse particle mass median diameter with an increasing FM-to-CM concentration ratio. Finally, our results illustrate one of the main problems associated with the use of real impactors to sample particles at relative humidity (RH) values less than 40%. While PM10, concentrations obtained by means of the MOUDI and Partisol were in excellent agreement, CM concentrations measured by the MOUDI were low by 20%, and FM concentrations were high by a factor of 5, together suggesting particle bounce at low RH.

This work was supported by the Southern California Particle Center and Supersite (SCPCS), funded by EPA under the STAR program through Grants #53-4507-0482 and 53-4507-7721 to the University of Southern California (USC). EPA, through its Office of Research and Development, collaborated in this research and preparation of this manuscript. The manuscript has been subjected to Agency review and approved for publication. Mention of trade names or commercial products does not constitute an endorsement or recommendation for use. Finally, a provisional patent application has been filed to the U.S. Patent Office by the USC Office of Technology and Licensing (USC File No. 3102).
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Citation:Misra, C., M. D. Geller, P. Shah, C. Sioutas, and P. A. Solomon. Development and Evaluation of a Continuous Coarse (PM10-PM2.5) Particle Monitor. JOURNAL OF AIR AND WASTE MANAGEMENT 51(9):1309-1317, (2001).
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Contact: Liz Hope - (919) 541-2785 or hope.elizabeth@epa.gov
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Division: Human Exposure & Atmospheric Sciences Division
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Branch: Process Modeling Research Branch
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Product Type: Journal
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Published: 09/01/2001
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Related Entries:
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Bullet Item PM Supersites Program
spacer Relationship Reason:   A Project of the Product
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Last Updated on Monday, October 22, 2007
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