Abstract
There are over 1.3 billion onroad vehicles globally. Vehicle operation contributes significantly to global energy use and emissions of greenhouse gas, criteria, and mobile source air toxic air pollutants. Vehicle emissions lead to adverse effects on human health, including approximately 200,000 premature deaths globally. The objective of this work is to quantify the real-world energy use and emissions from onroad transport, to quantify the how sensitivity of emissions to infrastructure, vehicle technology, fuels, and operator behavior, and to quantify exposures to transportation-related emissions in near-road and on-road microenvironments. Measurements of vehicles energy use and tailpipe exhaust emissions were made under real-world operating conditions using portable emission measurement systems (PEMS). Vehicle emissions are highly sensitive to second-by-second speed trajectories, which leads to spatial variation in emission source strength. Because real-world emissions are highly episodic, a potentially effective approach to emissions management is to reduce the frequency and severity of short-term episodes of high emissions. Implications for near road air quality and human exposure to traffic-related air pollution are discussed.
Dr. Frey conducts research on measurement and modeling of the activity, energy use, and emissions of onroad and nonroad vehicles, and regarding human exposure to air pollution. He chaired the Clean Air Scientific Advisory Committee of the U.S. Environmental Protection Agency and currently serves on the EPA Science Advisory Board. He has also served in expert and advisory roles for the National Research Council, the World Health Organization, and the Inter-Governmental Panel on Climate Change, and contributed to a report to the U.S. Congress on Transportation’s Role in Reducing U.S. Greenhouse Gas Emissions. He is a Fellow of the Air & Waste Management Association and a Fellow and past president of the Society for Risk Analysis. He is a visiting professor in the Division of Environment and Sustainability at the Hong Kong University of Science and Technology. His degrees include B.S. Mechanical Engineering from the University of Virginia, Master of Engineering in Mechanical Engineering from Carnegie Mellon University, and PhD in Engineering and Public Policy from Carnegie Mellon University.