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On-Road Measurement of Light-Duty Gasoline and Heavy-Duty Diesel Vehicle Emissions
This page updated March 5, 2009
Chair’s Air Pollution Seminar |
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Friday, May 8, 2009
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On-Road Measurement of
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Robert A. Harley, Ph.D.
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Emissions from
light-duty (LD) gasoline and heavy-duty (HD) diesel vehicles were
measured at the Caldecott tunnel in the San Francisco Bay area in
summer 2006, with comparisons to results from previous years at the
same site made to quantify emission trends over time. LD vehicle
emissions of nitrogen oxides, volatile organic compounds, carbon
monoxide, and particulate matter (PM) continue to decline over time due
to fleet turnover effects and improved emission control technologies on
new vehicles. Some effects of the switch from methyl-tert butyl ether (MTBE) to ethanol in California gasoline were observed. Substantial reductions in HD diesel truck emissions of PM were also observed between 1997 and 2006. The distributions of black carbon (soot) and ultrafine particle number emissions from individual diesel trucks were measured as part of this study, and sub-populations of high-emitting trucks were identified. NOx from HD trucks has been decreasing more slowly than for LD vehicles over the last decade, with the result that the relative importance of diesel engines as a source of NOx emissions in California has increased dramatically. Diesel engines are also an important source of direct emissions of aldehydes, which are malodorous, toxic, and reactive in the atmosphere. Exhaust emissions of ammonia from LD vehicles used to be negligible, then increased with the adoption of three-way catalytic converters, and appear to have declined since 1999 as carbon monoxide emissions and air/fuel ratio for LD vehicles have been brought under better control.
Robert A. Harley Ph.D., is a Professor in the Department
of Civil and Environmental Engineering at the University of California,
Berkeley, where he has been on the faculty since 1993. Dr.
Harley's research focuses on air quality and sustainable
transportation; he is an author of 60 papers published in peer-reviewed
scientific journals. Professor Harley currently serves as Environmental
Engineering faculty group leader (2007-09). Dr. Harley is
also Deputy Department Head for Atmospheric Sciences in the
Environmental Energy Technologies Division of Lawrence Berkeley
National Laboratory, a U.S. Department of Energy science lab located
adjacent to campus. Dr. Harley received the National Science
Foundation's young investigator (CAREER) award in 1996, as well as a
visiting scientist fellowship (1999-2000) at the University of
Colorado/NOAA Aeronomy Lab in Boulder. Professor Harley served for 3
years as Vice Chair of the Civil and Environmental Engineering
Department at Berkeley (2001-04), chairing committees that were
responsible for undergraduate curriculum and graduate student
admissions. Professor Harley holds a bachelor's degree in
Engineering Science (Chemical Engineering option) from the University
of Toronto; and both M.S. and a Ph.D. degree in Environmental
Engineering Science from the California Institute of Technology
(Caltech).
For information
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