ARB Research Seminar

This page updated June 19, 2013

Source Apportionment of Fine and Ultrafine Particles in California

Michael J. Kleeman, Ph.D., Department of Civil and Environmental Enginering, University of California, Davis

October 09, 2008
Cal EPA Headquarters, 1001 "I" Street, Sacramento, CA

Research Project


Atmospheric Particulate Matter (PM) is associated with increased human mortality and morbidity in many epidemiological studies. It has been postulated that ultrafine particles (Dp < 0.1 Ám) (PM0.1) are more pathogenic and are thus a likely candidate for some observed correlation between fine PM and adverse health. The composition and source origin of ultrafine particles must be determined to fully investigate their relationship with human health.

In the current study, source profiles for particles smaller than 0.1 Ám in diameter (PM0.1) were measured from light-duty gasoline-powered vehicles, heavy-duty diesel vehicles, pine wood combustion, oak wood combustion, eucalyptus wood combustion, rice straw combustion, and meat cooking. PM0.1 concentrations in the roadside environment adjacent to a busy freeway were dominated by contributions from gasoline and diesel with smaller contributions from lubricating oil. Ambient air measurements at Sacramento, Modesto, and Bakersfield showed that the majority of the PM0.1 mass was composed of organic carbon with smaller amounts of elemental carbon. Wood combustion and meat cooking account for the majority of the PM0.1 organic carbon and therefore the majority of the PM0.1 mass. Gasoline fuel, diesel fuel, and lubricating oil accounted for the majority of the PM0.1 elemental carbon. These findings reflect the proximity of the sampling locations to each source type, and indicate that future inhalation exposure studies should also consider including wood combustion and meat cooking sources as potential causes of adverse health effects in central California cities during cold winter stagnation events.

Speaker Biography

Michael J. Kleeman, Ph.D., is a professor of the Department of Civil and Environmental Engineering at the University of California, Davis. Dr. Kleeman's main interests are the study of urban and regional air quality problems with an emphasis on the size and composition of atmospheric particles and gas-to-particle conversion processes. Professor Kleeman's research program balances experiment, theory, and modeling to approach air quality problems from multiple directions. Current projects include the climate impacts on air quality in California, health effects of airborne particles, and agricultural contributions to air pollution.

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