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Darrell Sonntag conducted independent research on the topic “Modeling the Temporal and Size Distributions of Diesel Particulate Matter Emissions.” His academic advisor was Dr. Oliver Gao of Cornell University and his professional advisor was Larry McAuliffe, NYMTC’s Sustainability Manager. Diesel particulate matter emissions are a serious health threat in the NYMTC region. However, little is known about important characteristics of particle emissions, including the size-distribution of fine and ultrafine particles. For his September 11th Memorial Program research, Darrell analyzed the size-distribution of particulate matter emissions from diesel transit buses and alternative fueled passenger cars. This research will help better understand the health risks from current and future transportation-source emissions in the NYMTC region.


Darrell Sonntag graduated with his Ph.D. in February of 2010, and after a short post-doctoral appointment at Cornell University, took a position as an AAAS Science & Technology Policy Fellow and began work with the US Environmental Protection Agency’s Office of Transportation and Air Quality in Washington DC. He is currently in this position and is conducting policy-focused research on the impact of potential emissions regulations on public health and the environment. Darrell indicated, “The memorial aspect of the internship helped me to appreciate my opportunities to study and apply knowledge to build a better and safer world. It gave me a stronger desire to do my best with the awarded funds to make a meaningful difference in the world. I’m also grateful for the opportunity to present my research at NYMTC headquarters. I felt that NYMTC really honored our work and was interested in what we had accomplished.”

Darrell feels that his professional advisor, Larry McAuliffe, provided valued assistance on conducting research and helped with his choice to conduct research that could influence “real-world decisions.” He conveyed that his opportunity gave him a broader perspective on the role of public transportation agencies in overcoming environmental challenges.

A review of his research conducted with September 11th Memorial Program funds appeared in the following journal article: Diane U. Keogh and Darrell Sonntag, Challenges and Approaches for Developing Ultrafine Particle Emission Inventories for Motor Vehicle and Bus Fleets, Atmosphere 2011, 2(2), 36-56. Darrell also had the opportunity to make several presentations which were at least partially based on his September 11th Memorial Program work at various conferences.

Darrell Sonntag
Civil Engineering