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H. Christopher Frey


Glenn E. Futrell Distinguished University Professor

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Department of Civil,

Construction, and

Environmental Engineering


North Carolina State University
Raleigh, NC 27695-7908

Telephone: (919) 515-1155

Email:  frey (at)

Research Interests



Current and Recent Projects

Past Projects

Computer Laboratory

Frey Research Group

Professional Activities

Real-World Vehicle Emissions

My interests are broadly in energy and environmental systems, including:  modeling and evaluation of advanced energy conversion (e.g.,combustion, gasification) and environmental control systems; measurement and modeling of real-world fuel use and emissions of onroad and nonroad vehicles; development and application of methods for quantification of variability and uncertainty and for sensitivity analysis in systems models; and exposure and risk analysis.  Air pollutant emissions of interest include criteria pollutants, hazardous air pollutants (“air toxics”), particulate matter, and greenhouse gases.  More details on my teaching, current and past research activities, publications, professional advisory activities, research group, and computer laboratory are available in the links above.  [link to CCEE department webpage for Dr. Frey]


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Latest News:


·         Dr. Frey was recognized by Environmental Science and Technology with an “Excellence in Review Award” in recognition of going "the extra distance to write reviews that were truly exceptions."  Only 18 awards were given internationally, of which only 7 in the U.S. were selected, based on about 10,000 reviews submitted to ES&T in the past year (  November 2017

·         Dr. Frey recently gave a seminar on “Denying Denialism:  Uncovering the Methods and Institutions of Climate Change Denial  The abstract, slides, and video for this seminar are available.

·         The Transportation and Air Quality Committee (ADC20) of the Transportation Research Board selected a paper authored by Dr. H. Christopher Frey and graduate students Maryam Delavarrafiee and Sanjam Singh as its "Spotlight Presentation" for the 2017 TRB Annual Meeting.  The paper, "Real-World Freeway and Ramp Activity and Emissions for Light Duty Gasoline Vehicles," was ranked 1st among 110 papers reviewed by ADC20 for the Annual Meeting.

·         Dr. H. Christopher Frey who is a member of the Board of Directors of the Air & Waste Management Association (A&WMA), was elected in November 2016 as a 2017 Vice President of the A&WMA.  He will join the A&WMA Executive Committee in addition to continuing to serve on the board.

·         Five recently published journal papers:       

1.    Khan, T., and H.C. Frey, “Comparison of real-world and certification emission rates for light duty gasoline vehicles,” Science of the Total Environment,             622–623: 790–800 (May 2018). (free access)

2.    Li, Z., W. Che, H.C. Frey, A.K.H. Lau, “Factors Affecting Variability in PM2.5 Exposure Concentrations in a Metro System,” Environmental Research, 160C:20-26 (2017). (free access until 11/10/17)

3.    Frey, H.C., M. Delavarrafiee, and S. Singh, “Real-World Freeway and Ramp Activity and Emissions for Light Duty Gasoline Vehicles,” Transportation Research Record, 2627:17-25 (2017).

4.    Li, Z., W. Che, H.C. Frey, A.K.H. Lau, “Characterization of PM2.5 Exposure Concentration in Transport Microenvironments Using Portable Air Monitors,” Environmental Pollution, 228:433-442 (2017).

5.    Graver, B.M., H.C. Frey, and J. Hu, “Effect of Biofuels on Real-World Emissions of Passenger Locomotives,” Environmental Science and Technology, 50(21):12030-12039, DOI:  10.1021/acs.est.6b03567, October 3, 2016. (

More publications

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Portions of this web site are based upon work supported by the
National Science Foundation under Grant No. 9701502.

Any opinions, findings, and conclusions or recommendations expressed in this web site
are those of the author(s) and do not necessarily reflect the views of the
National Science Foundation.