Determination of the contributions of light duty and heavy duty vehicle emissions to ambient particles in California

This report describes a new approach for particulate (PM) source apportionment, using meteorological, gas phase, and single particle source signatures, that has been developed and successfully tested for identifying and apportioning ambient particles in California. A central component of these studies involves using aerosol time-of-flight mass spectrometry (ATOFMS). This technique analyzes the size and chemical composition of single particles in real-time for determining the size-resolved mass spectral source signatures of the particulate exhaust emissions from heavy duty diesel vehicles (HDDV) and gasoline powered light duty vehicles (LDV) that can be used for ambient source apportionment. The source signatures were measured by directly sampling PM emissions from multiple vehicles operating on different driving cycles while on a chassis dynamometer. Differences between HDDV and LDV source seeds are discussed. The second and final phase of this project involved sampling ambient particles inside a tunnel and alongside a major freeway. In the freeway study, a high fraction (70-85%) of ambient particles were shown to match the dynamometer source seeds, indicating that the dynamometer seeds are truly representative of “real-world” emissions. The difference signatures from LDV and HDDV allow for differentiation of ambient particles from multiple sources including vehicles, biomass, and meat cooking. The established ATOFMS signature libraries for HDDV and LDV exhaust particles will be used in future ATOFMS apportionment studies which will detail the fraction of vehicle emissions in particulate matter in ambient air throughout California.

  • Record URL:
  • Supplemental Notes:
    • Also available online via the CARB website (
  • Corporate Authors:

    California Environmental Protection Agency

    Air Resources Board

    California Air Resources Board

    1001 I Street, P.O. Box 2815
    Sacramento, CA  United States  95812

    University of California, San Diego

    Department of Chemistry and Biochemistry
    San Diego, CA  United States 
  • Authors:
    • Prather, Kimberly A
  • Publication Date: 2005-5


  • English

Media Info

  • Pagination: xviii, 218 p.

Subject/Index Terms

Filing Info

  • Accession Number: 01007032
  • Record Type: Publication
  • Source Agency: UC Berkeley Transportation Library
  • Files: CALTRANS
  • Created Date: Nov 8 2005 8:41AM