MOBILE SOURCE ULTRA-FINE PM RESEARCH

Project No. A-66

Leaders:   R. S. MacArthur
                  J.C. Ball

Scope and Objective

The objective of this project is to summarize mobile source Ultra Fine Particulate Matter (UFPM) issues and research to develop insight into future mobile source UFPM research needs by providing a summary document that will be a common starting point for CRC to investigate UFPM.  This includes assessments of the magnitude from mobile source emissions, physical and chemical dynamics in the ambient air, and toxicology and epidemiology.

Current Status and Future Program

Examining UFPM (aerodynamic diameter less than 0.1 micrometers [100 nanometers]) from mobile sources is important because of urban population exposure, the large gradient with distance (~100 m) from the source, and the indicated health effects.  UFPM has been described by some as being more toxic than PM2.5.  Source characterization is still underway—one purpose of current UFPM measurement at the Caldecott Tunnel is to investigate the contribution of LD gasoline vehicles to the UFPM burden.  Similarly, population exposure to UFPM is not well known since its spatial variation has not been measured.  This also applies to indoor exposures.

The project approach included a literature search with documentation.  The project deliverable was a Final Report that will be used as a basis to direct future committee research. The Final Report was reviewed and approved by the committee and was posted on the CRC website (February 2008).

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