PLUTO

PROJECTING THE IMPACT OF LAND USE AND TRANSPORTATION ON FUTURE AIR QUALITY

IN THE UPPER MIDWESTERN UNITED STATES

EPA ABSTRACT

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OVERVIEW

How will land use decisions made today influence travel behavior and air quality tomorrow? Project PLUTO is an EPA funded study designed to investigate the impact of regional land use patterns on air quality throughout the upper Midwestern United States. The principal goal of this research is to evaluate the effectiveness of "smart growth" land use policies in combating ozone formation and fine particulate air pollution between today and 2050. Through the integration of travel survey data with a set of mobile source emissions and air chemistry models, we will assess the influence of regional land use and technology change scenarios, coupled with ongoing changes in climate, on air quality throughout the states of Minnesota, Wisconsin, Illinois, Michigan, Indiana, and Ohio. Project PLUTO is the first study to evaluate the potential for smart growth land use strategies to improve regional air quality over time and in comparison with conventional technological strategies, such as power plant scrubbers and hybrid vehicles.

Over a decade since the passage of the Clean Air Act Amendments of 1990, many large metropolitan regions of the United States remain in non-attainment for one or more criteria air pollutants regulated by the U.S. Environmental Protection Agency. Confronted with ever increasing rates of personal vehicle travel and energy consumption, unhealthy levels of regional pollutants such as tropospheric ozone (O3) and fine particulate matter (PM) have persisted – and, in some cases, increased – in many regions of the country, despite significant reductions in both mobile and point source emissions achieved through technological emissions controls. While land use patterns characterized by moderate to high population and employment densities, an intermixing of compatible land uses, and pedestrian and transit supportive design techniques have been associated with reduced rates of vehicle travel in the planning literature, few studies have sought to measure the potential benefits of these planning strategies for regional air quality over time. In light of the many uncertainties pertaining to not only the nature of future development patterns, but also to changes in vehicle technologies, energy demand, inter-regional transport of air pollution, and regional climates, an integrated modeling framework is needed to assess the potential for such strategies to measurably improve air quality over the next half century.

Research Approach

The research approach will combine national demographic and travel survey data with vehicle emissions (MOBILE6), regional air quality (CMAQ), and global atmospheric chemistry (MOZART) models to associate land use patterns with O3 and PM in future years. Through the use of the USDOT’s Nationwide Personal Transportation Survey “transferability component,” we will derive estimates of census tract level VMT that may be projected to future time periods in response to “business as usual” and “smart growth” development scenarios (Figure 1). Adjusting for regional and temporal variability in vehicle fleet composition (including hybrid vehicle fractions), travel speeds, coldstart fractions, and ambient temperatures, MOBILE6 will be used to generate a set of vehicle emissions factors that, in combination with the VMT estimates, will be used to estimate daily vehicle emissions. In concert with point source emissions estimates derived from an energy demand analysis, these vehicle emissions estimates will be aggregated to 36 km x 36 km grid cells and incorporated into CMAQ to model regional O3 and PM chemistry under variable development, technology, and climate change scenarios. As a final step, MOZART will be employed to assess the influence of continental and global scale precursor transport on O3 and PM throughout the study region (Figure 2).

Expected Results

This research will make three principal contributions to the fields of land use and air quality management:

1. Development of an integrated land use, vehicle travel, and air emissions framework for evaluating the mobility and air quality implications of alternative regional land  development scenarios. A central contribution of this research will be the development of a highly transparent and readily transferable modeling framework that may be employed by an array of local, state, and federal planning agencies to assess the local and regional air quality implications of land development decisions.

2. Derivation of tract level vehicle emissions estimates of NOx, VOC, CO, and PM for alternative land development, hybrid vehicle dissemination, and climate change scenarios. As smart growth planning strategies generally require many years for implementation, the ability to forecast air quality effects several decades into the future is critical for assessing the potential utility of these strategies in the context of ongoing climatological changes.

3. Estimation of O3 and PM concentrations at a 36 km2 resolution for alternative land development, technological emissions control, and climate change scenarios. The ozone and fine particulate forecasts generated by this research will provide the first comprehensive assessment of disaggregate land use change, emissions production, and regional air quality over a multi-state study region.

Project Team

Dr. Brian Stone, PI, City and Regional Planning Program, Georgia Institute of Technology

Dr. Tracey Holloway, PI, Nelson Institute of Environmental Studies, UW-Madison

Adam Mednick, Dept. of Urban and Regional Planning, UW-Madison

Scot Spak, Nelson Institute of Environmental Studies, UW-Madison

For more information, please contact Brian Stone (stone@gatech.edu) or Tracey Holloway (taholloway@wisc.edu). This research is funded by an EPA Science to Achieve Results Grant #R831840.