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H. Christopher Frey

Research Interests



Current and Recent Projects

Past Projects

Computer Laboratory

Frey Research Group

Professional Activities

Real-World Vehicle Emissions

Recent and Current Externally-Sponsored Research Projects


      Title:                            Development and Evaluation of Methodological Framework for Real-World Vehicle Energy Use and Emissions Estimation at Multiple Temporal and Vehicular Scales

Investigators:               H.C. Frey (PI) and N.M. Rouphail (Co-PI)

Granting Agency:        National Science Foundation

Dates:                          May 15, 2008 to May 14, 2011

Brief Description:       Vehicle Fuel Use and Emissions (FU&E) have substantial national energy and environmental implications, but are confounded by intra/inter-vehicle variability and, therefore, require scientific inquiry to develop an improved basis for their characterization and management.  The main objectives of this research are to:  (1) quantify intra-vehicle variability in FU&E due to inter-driver variability, cold start, ambient conditions, and road grades; (2) develop FU&E models based on multiple levels of vehicle aggregation and multiple temporal scales; and (3) evaluate the interface of these models with transportation models and for use with real-time vehicle detection.


      Title:                            A Spatial-Temporal Modeling Approach for Evaluating the Impact of Environmental Stressors, in Conjunction with Human Activity, on Human Health

Investigators:               M. Fuentes (Statistics), H. Christopher Frey, S. Ghosh (Statistics)

Granting Agency:        National Institutes of Health

Funding Amount:        $333,280 in Year 1 ($66,923 for Frey portion), renewable for up to three years.

Dates:                          January 1, 2008 to December 31, 2010

Brief Description:       The focus of this research is on development of new statistical methods for investigating the spatial and temporal associations between environmental stressors and adverse human health effects.  The environmental stressor investigated here will be fine particulate matter (PM) less than 2.5 microns in diameter (PM2.5).  Health effects to be assessed including mortality and morbidity.  A key feature of this work will be to quantify human exposure to PM2.5 based on ambient concentrations of PM2.5, the penetration of ambient PM2.5 into various microenvironments, and the activity patterns of humans with respect to time spent in each microenvironment.  The use of an exposure-based metric for environmental stressors on humans, rather than the more conventional ambient concentration metric, is hypothesized to lead to a better capability to explain differences in the rate of mortality and morbidity associated with PM2.5, such as when comparing results for different geographic regions. 


Title:                            Spatial Temporal Analysis of Health Effects Associated with Sources and Speciation of Fine Particulate Matter

Investigators:               M. Fuentes (Statistics), H. Christopher Frey, Y. Zhang (MEAS), M. Bell (Yale U.), F. Dominici (Johns Hopkins)

Granting Agency:        U.S. Environmental Protection Agency STAR Grants Program

Dates:                          November 15, 2008 to November 14, 2011

Brief Description:        The overall objective of this research is to investigate the adverse health outcomes associated with population exposure to fine particulate matter (PM) less than 2.5 microns in diameter (PM2.5), ans speciation of the fine PM to characterization geographic differences, sources, and population heterogeneity in putatively PM2.5 mediated health effects.  We will answer the following questions:  What is the recommended framework to integrate atmospheric models with monitoring data and other sources of information (i.e. source apportionment) to obtain a better spatial and temporal characterization of fine PM components and sources?  How to use source apportionment and exposure assessment approaches in national epidemiological studies, while characterizing different sources of uncertainty in the models and the data?


      Title:                            Regional Development, Population Trend and Technology Change Impacts on Future Air Pollution Emissions                      

Investigators:               Nagui M. Rouphail and H. Christopher Frey

Granting Agency:        U.S. Environmental Protection Agency STAR grant via University of North Carolina at Chapel Hill, and Center for Transportation and the Environment

Dates:                          November 2004 to November 2008

Brief Description:       This research tests the hypothesis that smart-growth development patterns can significantly influence the quantity and location of direct and indirect emissions from mobile sources. The patterns of interest include the type of development and its location.  We will develop a general method for exploring the leverage that smart-growth development patterns have on the spatial pattern and quantity of emissions from mobile sources. We will explore scenarios and chart the envelope of the effectiveness of smart growth as a means for reducing emissions. We will determine whether substantial emissions reductions are feasible with forecasts of the market penetration of smart growth.    


Title:                            Measurement and Evaluation of Alternative Fuels and Technologies for a Passenger Rail Diesel Locomotive Prime Mover Engine

Investigators:               H.C. Frey (PI)

Granting Agency:        American Motive Power, Inc

Dates:                          May 16, 2009 to August 15, 2009

      Brief Description:        The primary objectives of the proposed study are to:  (1) Demonstrate a methodology for using a Portable Emissions Measurement System (PEMS) in combination with an engine dynamometer used for performance testing in order to obtain useful data regarding engine emissions; (2) Measure exhaust gas concentrations of CO2, CO, HC, NO, and PM during a sequence of parametric tests in order to provide a comparative  basis for assessing the effect of fuels, injectors, and engine parameter settings with respect to emissions; and (3) Develop baseline emission factors for the tested EMD 645 engine in units of g/sec, g/gallon, and g/bhp-hr that may be used as a basis for comparisons in future work or with other engine emissions data.


Title:                            Measurement and Evaluation of Fuels and Technologies for Passenger Rail Service in North Carolina

Investigators:               H.C. Frey (PI)

Granting Agency:        North Carolina Department of Transportation

Dates:                          August 16, 2009 to August 15, 2011

      Brief Description:        This project will include the following tasks:  (1) railyard measurement of fuel use and emission rates on the rebuilt or replaced engines on each locomotive, using ultra low sulfur diesel (ULSD) fuel and B20; (2) measurement real-world in-use “over-the-rails” activity, fuel use, and emissions for service between Raleigh and Charlotte; (3) assessment of the avoided fuel use and emissions from substitution of rail service for highway vehicle trips; (4) evaluation of the energy use and emissions implications of B20 versus ULSD using a life cycle inventory approach; and (5) evaluation of emerging alternative technologies for locomotives, such as hydrogen-fueled internal combustion engines (ICEs) and fuel cells (FCs).




Updated September 29, 2009