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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 will include 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 as being more
toxic than PM2.5. This is because subsequent to exposure, some
evidence indicates UFPM directly enters the bloodstream, suggesting particle
number or surface area is more important than mass. 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 will include a literature search with documentation. The project
deliverable will be a final report that will be used as a basis to seed future
committee research. A request for proposal has been issued, and the project
should start before the end of 2007.
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