Research: Urban sustainability engineering
I am interested in energy and environmental impacts of cities, especially urban transportation systems. My research group analyzes data and builds models to understand the air pollution, climate-change emissions, and health impacts of the built environment. The goal is to investigate approaches to improve the environmental and public health aspects of urban areas. Three main focus areas, and specific projects for each area, are listed below. Our research is supported by the National Science Foundation, the Environmental Protection Agency, and the State of Minnesota.
Air pollution and health
Urban air pollution is one of the top 15 causes of death, responsible for ~ 1% of deaths annual. In the U.S., air pollution is estimated to be responsible for the majority (~85%) of environmental health risks. A main goal for air quality engineering is prioritization: which emission sources should be reduced and how much? Our research aims to help address that question.
My group studies how much pollution people breathe from specific sources and what would be the health benefits from reducing those emissions. We often use a metric called intake fraction, which is the fraction of emissions from a source that are inhaled by people. Intake fraction quantifies the emission-to-intake relationship in a manner that is useful for cost-benefit analyses, health risk assessment, and other analyses that can help prioritize emission reductions among sources.
Current projects:
- Exposure benefits from emission reductions in California’s South Coast Air Basin: Mobility-based model (with Gurumurthy Ramachandran, Public Health, UMN)
- Environmental justice aspects of air pollution exposures in the South Coast Air Basin
- Intake fraction for wood-smoke particulate matter in Vancouver, British Columbia (with Michael Brauer, Environmental Health, University of British Columbia)
- Intake fraction for urban motor-vehicle emissions throughout the globe
- Evaluation of methods for summarizing meteorological data for intake fraction calculations (with Olivier Jolliet, Public Health, University of Michigan)
- Measurements of neighborhood-scale air pollution in a low-income and a medium-income neighborhood in Bangalore, India (with Gurumurthy Ramachandran, Public Health, UMN)
You can watch two brief air pollution "movies" by clicking here: diesel movie; benzene movie. [After clicking the link to open the file with Powerpoint, view as slide show (button F5).
The movie loops through 24 hours of concentrations in 1-hour time steps. To pause or un-pause, press the {left-arrow} or {right-arrow}; to exit, hit {Esc}. Credits: I made this movie with Abby Hoats, based on output from ENVIRON's CAMx model for
the South Coast Air Basin (map).]
Energy, climate, and sustainability
Scientific consensus on climate-change is that (1) unequivocally, the climate is changing, and (2) it is very likely (greater than 90% certainty) that those changes are caused by human actions. We have three options: mitigate, for example by reducing or sequestering emissions; adapt, for example, social and technical change that reflects the environmental change; or, suffer, if we are unprepared for negative climate-change impacts. Current and future responses will involve some combination of those three options. Mitigation and adaptation in the next 5 – 15 years are unlikely to involve a single “magic bullet” technical shift; instead, a suit of approaches is needed. My group is interested in understanding and quantifying options for climate-mitigation for transportation systems.
Current projects:
- Climate-mitigation for the transportation system in Minnesota: changes to vehicles, fuels, and transportation and land-use planning (with Elizabeth Wilson, Public Policy, UMN; David Kittleson and Win Watts, Mechanical Engineering, UMN).
- Energy-efficient urban form: how much can smart growth and other urban design attributes contribute to climate-mitigation goals?
- Transportation-CO2 emissions trends for rapidly-developing countries in Asia (with Peter Marcotullio, Geography, Hunter College)
- Greenhouse gas and air pollution impacts of bio-fuels (with Jason Hill and Steve Polasky, Applied Economics, David Tilman, Ecology, Evolution, and Behavior, and Sangwon Suh, Bio-based Products, UMN)
Environmental and health impacts of urban form
In approximately 2007, for the first time in history, the global population shifted from being a majority rural to a majority urban. In coming decades, urban populations are expected to double (to ~ 6 billion), while rural populations (~3 billion) hold constant or decline slightly. The majority of this urban growth will occur in developing countries. I am interested in how the size, shape, and layout of cities impact their environmental footprint.
Current projects:
- Air pollution and exercise levels in Vancouver: “healthy neighborhoods” (with Michael Brauer, Environmental Health, University of British Columbia; Larry Frank, Community and Regional Planning, University of British Columbia)
- Understanding and modeling US urban sprawl, 1950 – 2000
- Energy-efficient urban form: how much can smart growth and other urban design attributes contribute to climate-mitigation goals?
- Using satellite data to explore the connection between urban form (sprawl versus compact development) and air pollution (with Dylan Millet, Soil, Water, & Climate, UMN; Steven Manson, Geography, UMN)
