Peer-Reviewed Archival Journal Papers

  1. Rubin, E.S., J.S. Salmento, and H.C. Frey, “Cost-Effective Emission Controls for Coal-Fired Power Plants,” Chemical Engineering Communications, 74:155-167 (1988).
  2. Frey, H.C., and E.S. Rubin, “Probabilistic Evaluation of Advanced SO2/NOxControl Technology,” Journal of the Air and Waste Management Association, 41(12):1585-1593 (December 1991).
  3. Frey, H.C., and E.S. Rubin, “Evaluation Method for Advanced Acid Rain Compliance Technology,” Journal of Energy Engineering, 118(1):38-55 (April 1992).
  4. Frey, H.C., and E.S. Rubin, “Evaluation of Advanced Coal Gasification Combined-Cycle Systems Under Uncertainty,” Industrial and Engineering Chemistry Research, 31(5):1299-1307 (May 1992).
  5. Diwekar, U.M., H.C. Frey, and E.S. Rubin, “Synthesizing Optimal Flowsheets: Applications to IGCC System Environmental Control,” Industrial and Engineering Chemistry Research, 31(8):1927-1936 (August 1992).
  6. Frey, H.C., and E.S. Rubin, “Integration of Coal Utilization and Environmental Control in Integrated Gasification Combined Cycle Systems,” Environmental Science and Technology, 26(10):1982-1990 (October 1992).
  7. Frey, H.C., E.S. Rubin, and U.M. Diwekar, “Modeling Uncertainties in Advanced Technologies: Application to a Coal Gasification System with Hot Gas Cleanup,” Energy 19(4):449-463 (1994).
  8. Shih, J.S., and H.C. Frey, “Coal Blending Optimization Under Uncertainty,” European Journal of Operations Research, 83(3):452-465 (1995).
  9. Frey, H.C., and D.S. Rhodes, “Characterizing, Simulating, and Analyzing Variability and Uncertainty: An Illustration of Methods Using an Air Toxics Emissions Example,” Human and Ecological Risk Assessment: an International Journal, 2(4):762-797 (December 1996).
  10. Diwekar, U.M., E.S. Rubin, and H.C. Frey, “Optimal Design of Advanced Power Systems Under Uncertainty,” Energy Conversion and Management, 38(15):1725-1735 (1997).
  11. Rubin, E.S., J.R. Kalagnanam, H.C. Frey, and M.B. Berkenpas, “Integrated Environmental Control Concepts for Coal-Fired Power Plants,” Journal of the Air and Waste Management Association, 47(11):1180-1188 (November 1997).
  12. Agarwal, P., and H.C. Frey, “Modeling and Evaluation of the Externally Fired Combined Cycle Using ASPEN,” Journal of Energy Engineering, 123(3):69-87 (December 1997).
  13. Frey, H.C., and Z. Iwanski, “Probabilistic Methodology for Risk Assessment of New Energy Technologies and Application to Gasification Repowering for an Oil Refinery in Poland,” Energy Conversion and Management, 39 (16/18):267-274 (1998). [special issue:  Florence World Energy Research Symposium (FLOWERS ’97)].
  14. Frey, H.C., and D.S. Rhodes, “Characterization and Simulation of Uncertain Frequency Distributions: Effects of Distribution Choice, Variability, Uncertainty, and Parameter Dependence,” Human and Ecological Risk Assessment: an International Journal, 4(2):423-468 (April 1998).
  15. Frey, H.C., and D.E. Burmaster, “Methods for Characterizing Variability and Uncertainty: Comparison of Bootstrap Simulation and Likelihood-Based Approaches,” Risk Analysis, 19(1):109-130 (February 1999).
  16. Hanna, S.R., Z. Lu, H.C. Frey, N. Wheeler, J. Vukovich, S. Arunachalam, M. Fernau, and D.A. Hansen, “Uncertainties in Predicted Ozone Concentrations due to Input Uncertainties for the UAM-V Photochemical Grid Model Applied to the July 1995 OTAG Domain,” Atmospheric Environment, 35(5):891-903 (2001).
  17. Frey, H.C., and S. Bammi, “Quantification of Variability and Uncertainty in Lawn and Garden Equipment NOx and Total Hydrocarbon Emission Factors,” Journal of the Air & Waste Management Association, 52(4):435-448 (April 2002).
  18. Frey, H.C., and S.R. Patil, “Identification and Review of Sensitivity Analysis Methods,” Risk Analysis, 22(3):553-578 (June 2002).
  19. Frey, H.C., and J. Zheng, “Quantification of Variability and Uncertainty in Air Pollutant Emission Inventories: Method and Case Study for Utility NOx Emissions,” Journal of Air & Waste Manage. Association, 52(9):1083-1095 (September 2002).
  20. Frey, H.C., and J. Zheng, “Probabilistic Analysis of Driving Cycle-Based Highway Vehicle Emission Factors,” Environmental Science and Technology, 36(23):5184-5191 (December 2002).
  21. Frey, H.C., and S. Bammi, “Probabilistic Nonroad Mobile Source Emission Factors,” ASCE Journal of Environmental Engineering, 129(2):162-168 (February 2003).
  22. Frey, H.C., A. Unal, N.M. Rouphail, and J.D. Colyar, “On-Road Measurement of Vehicle Tailpipe Emissions Using a Portable Instrument,” Journal of Air & Waste Manage. Assoc., 53(8):992-1002 (August 2003).
  23. Abdel-Aziz, A., and H.C. Frey, “Quantification of Hourly Variability in NOx Emissions for Baseload Coal-Fired Power Plants,” Journal of the Air & Waste Management Association, 53(11):1401-1411 (November 2003).
  24. Abdel-Aziz, A., and H.C. Frey, “Development of Hourly Probabilistic Utility NOx Emission Inventories Using Time Series Techniques: Part I-Univariate Approach,” Atmospheric Environment, 37:5379-5389 (2003).
  25. Abdel-Aziz, A., and H.C. Frey, “Development of Hourly Probabilistic Utility NOx Emission Inventories Using Time Series Techniques: Part II-Multivariate Approach,” Atmospheric Environment, 37:5391-5401 (2003).
  26. Frey, H.C., and S. Li, “Quantification of Variability and Uncertainty in AP-42 Emission Factors: Case Studies for Natural Gas-Fueled Engines,” Journal of the Air & Waste Management Association, 53(12):1436-1447 (December 2003).
  27. Unal, A., N.M. Rouphail, and H.C. Frey, “Effect of Arterial Signalization and Level of Service on Measured Vehicle Emissions,” Transportation Research Record, Journal of the Transportation Research Board, No. 1842, pp. 47-56 (2003). DOI: 3141/1842-06.
  28. Unal, A., H.C. Frey, and N.M. Rouphail, “Quantification of Highway Vehicle Emissions Hot Spots Based Upon On-Board Measurements,” Journal of the Air & Waste Management Association, 54(2):130-140 (February 2004).
  29. Abdel-Aziz, A., and H.C. Frey, “Propagation of Uncertainty in Hourly Utility NOx Emissions Through a Photochemical Grid Air Quality Model: A Case Study for the Charlotte, NC Modeling Domain,” Environmental Science and Technology, 38(7):2153-2160 (2004).
  30. Patil, S.R., and H.C. Frey, “Comparison of Sensitivity Analysis Methods Based Upon Applications to a Food Safety Risk Model,” Risk Analysis, 24(3):573-585 (June 2004).
  31. Zheng, J., and H.C. Frey, “Quantification of Variability and Uncertainty Using Mixture Distributions: Evaluation of Sample Size, Mixing Weights and Separation between Components,” Risk Analysis, 24(3):553-571 (June 2004).
  32. Zhao, Y., and H.C. Frey, “Quantification of Variability and Uncertainty for Censored Data Sets and Application to Air Toxic Emission Factors,” Risk Analysis, 24(4):1019-1034 (2004).
  33. Frey, H.C., and Y. Zhao, “Quantification of Variability and Uncertainty for Air Toxic Emission Inventories With Censored Emission Factor Data,” Environmental Science and Technology, 38(22):6094-6100 (2004).
  34. Chen, J., and H.C. Frey, “Optimization Under Variability and Uncertainty: A Case Study for NOx Emissions Control for a Gasification System,” Environmental Science and Technology, 38(24):6741-6747 (2004).
  35. Zhao, Y., and H.C. Frey, “Development of Probabilistic Emission Inventory for Air Toxic Emissions for Jacksonville, Florida,” Journal of the Air & Waste Management Association, 54(11):1405-1421 (2004).
  36. Mokhtari, A., and H.C. Frey, “Recommended Practice Regarding Selection of Sensitivity Analysis Methods Applied to Microbial Food Safety Process Risk Models,” Human and Ecological Risk Assessment, 11(3):591-605 (2005).
  37. Zheng, J., and H.C. Frey, “Quantitative Analysis of Variability and Uncertainty with Known Measurement Error: Methodology and Case Study,” Risk Analysis, 25(3):663-676 (2005).
  38. Mokhtari, A., and H.C. Frey, “Sensitivity Analysis of a Two-Dimensional Probabilistic Risk Assessment Model Using Analysis of Variance,” Risk Analysis, 25(6):1511-1529 (2005).
  39. Frey, H.C., and Y. Zhu, “Improved System Integration for Integrated Gasification Combined Cycle (IGCC) Systems,” Environmental Science and Technology, 40(5):1693-1699 (March 2006).
  40. Mokhtari, A., H.C. Frey, and L.-A. Jaykus, “Application of Classification and Regression Trees (CART) for Sensitivity Analysis of the Escherichia coli O157:H7 Food Safety Process Risk Model,” Journal of Food Protection, 69(3):609–618 (March 2006).
  41. Zhang, K., and H.C. Frey, “Road Grade Estimation for On-Road Vehicle Emissions Modeling Using LIDAR Data,” Journal of the Air & Waste Management Association, 56(6):777-788 (June 2006).
  42. Silva, C.M, T.L. Farias, H.C. Frey, and N.M. Rouphail, “Evaluation of Numerical Models for Simulation of Real-World Hot-Stabilized Fuel Consumption and Emissions of Gasoline Light-Duty Vehicles.” Transportation Research Part D, 11(5):377-385 (2006).
  43. Miller, C.A., G. Hidy, J. Hales, C.E. Kolb, A.S. Werner, B. Haneke, D. Parrish, C. Frey, L. Rojas-Blanco, M. DesLauriers, B. Pennell, and J.D. Mobley, “Air Emissions Inventories in North America: A Critical Assessment,” Journal of the Air & Waste Management Association, 56(8):1115-1129 (August 2006).
  44. Mokhtari, A., H.C. Frey, and J. Zheng, “Evaluation and recommendation of sensitivity analysis methods for application to Stochastic Human Exposure and Dose Simulation (SHEDS) models,” Journal of Exposure Science and Environmental Epidemiology, 16(6):491-506 (Nov 2006).
  45. Mokhtari, A., and H.C. Frey, “Evaluation of Sampling-Based Methods for Sensitivity Analysis: Case Study for the coli Food Safety Process Risk Model,” Human and Ecological Risk Assessment, 12(6):1128-1152 (Dec 2006).
  46. Zhao, Y. and H.C. Frey, “Uncertainty for Data with Non-Detects: Air Toxic Emissions from Combustion,” Human and Ecological Risk Assessment, 12(6):1171-1191 (Dec 2006).
  47. Zhu, Y., and H.C. Frey, “Uncertainty Analysis of Integrated Gasification Combined Cycle (IGCC) Systems Based on Frame 7H versus 7F Gas Turbines,” Journal of the Air & Waste Management Association, 56(12):1649-1661 (Dec 2006).
  48. Frey, H.C., and K. Kim, “Comparison of Real-World Fuel Use and Emissions for Dump Trucks Fueled with B20 Biodiesel Versus Petroleum Diesel,” Transportation Research Record, 1987:110-117 (2006). DOI: 3141/1987-12.
  49. Frey, H.C., N.M. Rouphail, and H. Zhai, “Speed- and Facility-Specific Emission Estimates for On-Road Light-Duty Vehicles based on Real-World Speed Profiles,” Transportation Research Record, 1987:128-137 (2006). DOI: 3141/1987-14.
  50. Vicari A.S., A. Mohktari, R.A. Morales, L.A. Jaykus, H.C. Frey, B.D. Slenning and P. Cowen, “Second-Order Modeling of Variability and Uncertainty in Microbial Hazard Characterization,” Journal of Food Protection, 70(2):363-372 (February 2007).
  51. Frey, H.C., N.M. Rouphail, H. Zhai, T.L. Farias, and G.A. Gonçalves, “Comparing Real-World Fuel Consumption for Diesel- and Hydrogen-Fueled Transit Buses and Implication for Emissions,” Transportation Research – Part D. 12:281-291 (June 2007).
  52. Zhu, Y., and H.C. Frey, “Simplified Performance Model of Gas Turbine Combined Cycle Systems,” ASCE Journal of Energy Engineering, 133(2):82-90 (June 2007).
  53. Zhang, K., and H.C. Frey, “Evaluation of Response Time of a Portable System for In-Use Vehicle Tailpipe Emissions Measurements,” Environmental Science and Technology, 42(1), 221–227 (2008).
  54. Frey, H.C., K. Zhang, and N.M. Rouphail, “Fuel Use and Emissions Comparisons for Alternative Routes, Time of Day, Road Grade, and Vehicles Based on In-Use Measurements,” Environmental Science and Technology, 42(7):2483–2489 (April 2008).
  55. Abolhasani, S., H.C. Frey, K. Kim, S. Pang, W. Rasdorf, P. Lewis, “Real-World In-Use Activity, Fuel Use, and Emissions for Nonroad Construction Vehicles: A Case Study for Excavators,” Journal of the Air & Waste Management Association, 58(8):1033-1046 (August 2008).
  56. Frey, H.C., Kim, K., S. Pang, W. Rasdorf, P. Lewis, “Characterization of Real-World Activity, Fuel Use, and Emissions for Selected Motor Graders Fueled with Petroleum Diesel and B20 Biodiesel,” Journal of the Air & Waste Management Association, 58(10):1274-1287 (October 2008).
  57. Zhai, H., H.C. Frey, and N.M. Rouphail, “A Vehicle-Specific Power Approach to Speed- and Facility-Specific Emissions Estimates for Diesel Transit Buses,” Environmental Science and Technology, 42(21):7985-7991 (November 2008).
  58. Frey, H.C., W.J. Rasdorf, K. Kim, S.H. Pang, P. Lewis, “Comparison of Real-World Emissions of B20 Biodiesel Versus. Petroleum Diesel for Selected Nonroad Vehicles and Engine Tiers,” Transportation Research Record, 2058:33-42 (2008).
  59. Frey, H.C., N.M. Rouphail, and H. Zhai, “Link-Based Emission Factors for Heavy-Duty Diesel Trucks Based on Real-World Data,” Transportation Research Record, 2058:23-32 (2008). DOI: 3141/2058-04.
  60. Frey, H.C., P.Y. Kuo, and C. Villa, “Methodology for Characterization of Long-Haul Truck Idling Activity under Real-World Conditions,” Transportation Research – Part D, 13D(8):516-523 (December 2008).
  61. Coelho, M., H.C. Frey, N.M. Rouphail, H. Zhai, and L. Pelkmans, “Assessing Methods for Comparing Emissions from Gasoline and Diesel Light-Duty Vehicles Based on Microscale Measurements,” Transportation Research – Part D, 14D(2):91-99 (March 2009).
  62. Ozkaynak, H., H.C. Frey, J. Burke, and R.W. Pinder, “Analysis of coupled model uncertainties in source to dose modeling of human exposures to ambient air pollution: a PM5 case-study,” Atmospheric Environment, 43(9): 1641-1649 (March 2009).
  63. Lewis, P., W. Rasdorf, H.C. Frey, S.H. Pang, and K. Kim, “Requirements and Incentives for Reducing Construction Vehicle Emissions and Comparison of Nonroad Diesel Engine Emissions Data Sources,” ASCE Journal of Construction Engineering and Management, 135(5):341-351 (May 2009).
  64. Bogen, K., A. Cullen, H.C. Frey, and P. Price, “Probabilistic Exposure Analysis for Chemical Risk Characterization,” Toxicological Sciences, 109(1):4-17 (May 2009).
  65. Frey, H.C., and P.Y. Kuo, “Real-World Energy Use and Emission Rates for Idling Long-Haul Truck Engines and Selected Idle Reduction Technologies,” Journal of the Air & Waste Management Association, 59(7):857-864 (July 2009).
  66. Zhai, H., H.C. Frey, N.M. Rouphail, G. Goncalves, and T. Farias, “Comparison of Flexible Fuel Vehicle and Life Cycle Fuel Consumption and Emissions of Selected Pollutants and Greenhouse Gases for Ethanol 85 Versus Gasoline,” Journal of the Air & Waste Management Association, 59(8):912-924 (August 2009).
  67. Pang, S.H., H.C. Frey, and W.J. Rasdorf, “Life Cycle Inventory Energy Consumption and Emissions for Biodiesel versus Petroleum Diesel Fueled Construction Vehicles,” Environmental Science and Technology, 43(16):6398-6405 (August 15, 2009).
  68. Frey, H.C., P.Y. Kuo, and C. Villa, “Effects of Idle Reduction Technologies on Real World Fuel Use and Exhaust Emissions of Idling Long-Haul Trucks,” Environmental Science and Technology, 43(17):6875–6881 (DOI: 10.1021/es900186e, published online July 30, 2009).
  69. Frey, H.C., H. Zhai, and N.M. Rouphail, “Regional On-Road Vehicle Running Emissions Modeling and Evaluation for Conventional and Alternative Vehicle Technologies,” Environmental Science and Technology, 43(21):8449–8455 (doi: 10.1021/es900535s, published online Sept 22, 2009).
  70. Choi, H.W. and H.C. Frey, “Estimating Light Duty Gasoline Vehicle Emission Factors at High Transient and Constant Speeds for Short Road Segments,” Transportation Research – Part D. 14(8):610–614 (2009). Available at:
  71. Frey, H.C., and K. Kim, “In-Use Measurement of Activity, Fuel Use, and Emissions of Cement Mixer Trucks Operated on Petroleum Diesel and B20 Biodiesel,” Transportation Research – Part D. 14(8):585-592 (2009).
  72. Lewis, P., H.C. Frey, and W. Rasdorf, “Development and Use of Emissions Inventories for Construction Vehicles,” Transportation Research Record, 2123:46-53 (2009). DOI: 3141/2123-06.
  73. Rasdorf, W., H.C. Frey, P. Lewis, K. Kim, S. Pang, and S. Abolhasani, “Field Procedures for Real-World Measurements of Emissions from Diesel Construction Vehicles,” ASCE Journal of Infrastructure Systems, 16(3):216-225 (Sept 2010).
  74. Choi, H.W., and H.C. Frey, “Estimating Diesel Vehicle Emission Factors at Constant and High Speeds for Short Road Segments,” Transportation Research Record, No. 2158:19-27 (2010). DOI: 3141/2158-03.
  75. Frey, H.C., W. Rasdorf, P. Lewis, “Comprehensive Field Study of Fuel Use and Emissions of Nonroad Diesel Construction Equipment,” Transportation Research Record, No. 2158:69-76 (2010). DOI: 3141/2158-09.
  76. Liu, X., H.C. Frey, and Y. Cao, “Estimation of In-Vehicle Concentration and Human Exposure for PM5 Based on Near Roadway Ambient Air Quality and Variability in Vehicle Operation,” Transportation Research Record, No. 2158:105-112 (2010). DOI: 10.3141/2158-13.
  77. Frey, H.C., K. Zhang, and N.M. Rouphail, “Vehicle-Specific Emissions Modeling Based Upon On-Road Measurements,” Environmental Science and Technology, 44(9):3594-3600 (2010).
  78. Choi, H.W., and H.C. Frey, “Method for In-Use Measurement and Evaluation of the Activity, Fuel Use, Electricity Use, and Emissions of a Plug-in Hybrid Diesel-Electric School Bus,” Environmental Science and Technology, 44(9):3601-3607 (2010).
  79. Cao, Y., and H.C. Frey, “Assessment of Inter-Individual and Geographic Variability in Human Exposure to Fine Particulate Matter in Environmental Tobacco Smoke,” Risk Analysis, 31(4):578-591 (2011). (April 2011).
  80. Liu, X., and H.C. Frey, “Modeling Of In-Vehicle Human Exposure to Ambient Fine Particulate Matter,” Atmospheric Environment, 45(27):4745-4752 (2011).
  81. Zhai, H., H.C. Frey, and N.M. Rouphail, “Development of A Modal Emissions Model for A Hybrid Electric Vehicle,” Transportation Research – Part D. 16(6):444-450 (August 2011).
  82. Cao, Y., and H.C. Frey, “Geographic differences in inter-individual variability of human exposure to fine particulate matter,” Atmospheric Environment, 45(32):5684-5691 (October 2011)
  83. Graver, B.M, H.C. Frey, and H.W. Choi (2011), “In-Use Measurement of the Activity, Energy Use, and Emissions of a Plug-in Hybrid Electric Vehicle,” Environmental Science and Technology, 45(20):9044-9051 (DOI: 1021/es201165d). (October 15, 2011).
  84. Lewis, P., M. Leming, H.C. Frey, and W. Rasdorf (2011), “Assessing the Effects of Operational Efficiency on Pollutant Emissions of Nonroad Diesel Construction Equipment,” Transportation Research Record, 2233:11-18 (DOI: 3141/2233-02).
  85. Lee, T., and H.C. Frey, “Evaluation of Representativeness of Site-Specific Fuel-based Vehicle Emission Factors for Area-wide Average Emissions,” Environmental Science and Technology, 46(12):6867–6873 (2012). DOI: 10.1021/es204451z.
  86. Rasdorf, W.R., P. Lewis, S.K. Marshall, I. Arocho, H.C. Frey, “Evaluation of Fuel Use and Emissions Over the Duration of a Construction Building Project,” ASCE Journal of Infrastructure Systems, 18(2):119-129 (2012). DOI: 10.1061/(ASCE)IS.1943-555X.0000071.
  87. Cao, Y., and H.C. Frey, “Modeling of Human Exposure to In-Vehicle PM5 from Environmental Tobacco Smoke,” Human and Ecological Risk Assessment, 18(3):608-626 (2012) DOI: 10.1080/10807039.2012.672894.
  88. Chang, H.H., M. Fuentes, and H. C. Frey, “Time Series Analysis of Personal Exposure to Ambient Air Pollution and Mortality Using an Exposure Simulator,” Journal of Exposure Science and Environmental Epidemiology, 22, 483-488 (2012) doi:10.1038/jes.2012.53. Sept/Oct 2012.
  89. Lewis, P., W. Rasdorf, M. Leming, and H.C. Frey, “Effects of Engine Idling on NAAQS Criteria Pollutant Emissions from Nonroad Diesel Construction Equipment,” Transportation Research Record, No. 2270, pp 67-75 (2012). DOI: 10.3141/2270-09.
  90. Sandhu, G.S., and H.C. Frey, “Real-World Measurement and Evaluation of Heavy Duty Truck Duty Cycles, Fuels, and Emission Control Technologies,” Transportation Research Record, 2270:180-187 (2012). DOI: 10.3141/2270-21.
  91. Marshall, S.K., W. Rasdorf, P. Lewis, H.C. Frey, “A Methodology for Estimating Emissions Inventories for Commercial Building Projects,” ASCE Journal of Architectural Engineering, 18(3):25-260 (September 2012).
  92. Jiao, W., H.C. Frey, and Y. Cao, “Assessment of Inter-Individual, Geographic, and Seasonal Variability in Estimated Human Exposure to Fine Particulate Matter.” Environmental Science and Technology, 46(22):12519-12526 (2012). DOI: 10.1021/es302803g.
  93. Frey, H.C., H.W. Choi, and K. Kim, “Portable Emissions Measurement System for Emissions of Passenger Rail Locomotives,” Transportation Research Record, 2289:56-63 (2012). DOI:  3141/2289-08.
  94. Abolhasani, S., and H.C. Frey, “Engine and Duty Cycle Variability in Diesel Construction Equipment Emissions,” ASCE Journal of Environmental Engineering, 139(2):261-268 (February 2013). DOI:  1061/(ASCE)EE.1943-7870.0000548.
  95. Yazdani, B., H.C. Frey, and G.S. Sandhu, “Road Grade Measurement Using In-Vehicle, Stand-Alone GPS with Barometric Altimeter,” ASCE Journal of Transportation Engineering, 139(6):605-611 (2013).
  96. Sandhu, G.S., and H.C. Frey, “Effects of Errors on Vehicle Emission Rates from Portable Emissions Measurement Systems,” Transportation Research Record, 2340:10-19 (2013). DOI:10.3141/2340-02.
  97. Mannshardt, E., K. Sucic, W. Jiao, F. Dominici, H.C. Frey, B. Reich, and M. Fuentes, “Comparing Exposure Metrics for the Effects of Fine Particulate Matter on Emergency Hospital Admissions,” Journal of Exposure Science and Environmental Epidemiology, 23:627-636 (doi:10.1038/jes.2013.39). (2013). .
  98. Graver, B.M., and H.C. Frey, “Comparison of Locomotive Emissions Measured during Dynamometer versus Rail Yard Engine Load Tests,” Transportation Research Record, 2341:23-33 (2013).
  99. Jiao, W., and H.C. Frey, “Method for Measuring the Ratio of In-Vehicle to Near-Vehicle Exposure Concentrations of Airborne Fine Particles,” Transportation Research Record, 2341:34-42 (2013).
  100. Salamati, K., M. Coelho, P. Fernandes, N.M. Rouphail, H.C. Frey and J. Bandeira, “Emission Estimation at Multilane Roundabouts: Effect of Movement and Approach Lane,” Transportation Research Record, 2389:12-21 (March 2013).
  101. Yazdani, B., and H.C. Frey, “Road Grade Quantification Based on Global Positioning System Data Obtained from Real-World Vehicle Fuel Use and Emission Measurements,” Atmospheric Environment, 85:179-186 (March 2014).
  102. Sandhu, G.S., H.C. Frey, S. Bartelt-Hunt, and E. Jones, “In-Use Measurement of the Activity, Fuel Use, and Emissions of Front-Loader Refuse Trucks,” Atmospheric Environment, 92:557-565 (August 2014).
  103. , J., H.C. Frey, G.S. Sandhu, B.M. Graver, G. Bishop, B. Shuchmann, J. Ray, “Method for Modeling Driving Cycle, Fuel Use, and Emissions for Over Snow Vehicles,” Environmental Science and Technology, 48(14):8258-8265, 2014, DOI: 10.1021/es501164j.
  104. Che, W., H.C. Frey, and A. Lau, “Assessment of the effect of population and diary sampling methods on estimation of school-age children exposure to fine particles,” Risk Analysis, 34(12):2066-2079 (December 2014), DOI: 10.1111/risa.12238, published online July 31, 2014.
  105. Jiao, W., and H.C. Frey, “Comparison of Fine Particulate Matter and Carbon Monoxide Exposure Concentrations for Selected Transportation Modes,” Transportation Research Record, 2428(2):54-62 (2014).
  106. Anya, A.R., N.M. Rouphail, H.C. Frey, and B. Schroeder, “Application of AIMSUN Micro Simulation Model in Estimating Emissions on Signalized Arterial Corridors,” Transportation Research Record, 2428(2):75-86 (2014).
  107. Sandhu, G.S., H.C. Frey, S. Bartelt-Hunt, and E. Jones, “In-Use Activity, Fuel Use, and Emissions of Heavy Duty Diesel Roll-off Refuse Trucks,” Journal of the Air & Waste Management Association, 65(3):306-323 (2015). DOI:10.1080/10962247.2014.990587.
  108. Che, W., H.C. Frey, and A.K.H. Lau, “Comparison of Sources of Variability in School Age Children Exposure to Ambient PM5,” Environmental Science and Technology, 2015, 49(3):1511–1520.
  109. Liu, B., and H.C. Frey, “Quantification and Application of Real-World Light Duty Vehicle Performance Envelope for Speed and Acceleration,” Transportation Research Record, 2503:128-136. DOI: 10.3141/2503-14 (2015).
  110. Liu, B., and H.C. Frey, “Variability in Light Duty Gasoline Vehicle Emission Factors from Trip-Based Real-World Measurements,” Environmental Science & Technology, 49(20):12525-12534. DOI: 10.1021/acs.est.5b00553 (2015)
  111. Salamati, K., N.M. Rouphail, H.C. Frey, B. Liu, and B.J. Schroeder, “A Simplified Method for Comparing Emissions at Roundabouts and Signalized Intersections,” Transportation Research Record, 2517:48-60. DOI: 10.3141/2517-06. (2015)
  112. Zhou, X., S. Tanvir, H. Lei, J. Taylor, B. Liu, N.M. Rouphail, and H.C. Frey, “Integrating a Simplified Emission Estimation Model and Mesoscopic Dynamic Traffic Simulator to Efficiently Evaluate Emission Impacts of Traffic Management Strategies,” Transportation Research – Part D, 37(2015):123-136.
  113. Graver, B.M., and H.C. Frey, “Comparison of Over-the-Rail and Rail Yard Measurements of Diesel Locomotives,” Environmental Science and Technology, 49(21):13031-13039 (2015), DOI: 10.1021/acs.est.5b02497.
  114. Sandhu, G.S., H.C. Frey, S. Bartelt-Hunt, and E. Jones, “Real-World Activity, Fuel Use, and Emissions of Diesel Side-Loader Refuse Trucks,” Atmospheric Environment, 129:98-104 (March 2016). doi:10.1016/j.atmosenv.2016.01.014
  115. Khan, T., and H.C. Frey, “Evaluation of Light Duty Gasoline Vehicle Rated Fuel Economy Based on In-Use Measurements,” Transportation Research Record, 2570:21-29 (2016). http://dx.doi.org/10.3141/2570-03
  116. Hu, J., H.C. Frey, and S.S. Washburn, “Comparison of Vehicle-Specific Fuel Use and Emissions Models Based on Externally and Internally Observable Activity Data,” Transportation Research Record, 2570:30-38 (2016).
  117. Che, W., H.C. Frey, and A.K.H. Lau, “Sequential Measurement of Intermodal Variability in Public Transportation PM5 and CO Exposure Concentrations,” Environmental Science and Technology, 50(16):8760-8769 (2016) DOI: 10.1021/acs.est.6b01594.
  118. Graver, B.M., and H.C. Frey, “Highway Vehicle Emissions Avoided by Diesel Passenger Rail Service Based on Real-World Data,” Urban Rail Transit, 2(3-4):153-171 (2016).
  119. 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 (2016), DOI: 1021/acs.est.6b03567, October 3, 2016.
  120. Li, Z., W. Che, H.C. Frey, A.K.H. Lau, “Characterization of PM5 Exposure Concentration in Transport Microenvironments Using Portable Air Monitors,” Environmental Pollution, 228:433-442 (2017).
  121. 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).
  122. Li, Z., W. Che, H.C. Frey, A.K.H. Lau, “Factors Affecting Variability in PM5 Exposure Concentrations in a Metro System,” Environmental Research, 160C:20-26 (2018).
  123. Khan, T., and H.C. Frey, “Comparison of Real-world Versus Certification Emission Rates for Light Duty Gasoline Vehicles,” Science of the Total Environment, 622-623:790-800 (2018).
  124. Delavarrafiee, M., and H.C. Frey, “Real-World Fuel Use and Gaseous Emission Rates for Flex Fuel Vehicles Operated on E85 versus Gasoline,” Air & Waste Management Association, 68(3):235-254 (March 2018).
  125. Kumar, P., I. Rivas, A.P. Singh, V.J. Ganesh, M. Ananya, H.C. Frey, “Dynamics of Coarse and Fine Particles Exposure in Transport Microenvironments,” npj Climate and Atmospheric Science, 1, 11, 2018, doi:10.1038/s41612-018-0023-y.
  126. Kumar, Prashant, Allison P. Patton, John L. Durant, H. Christopher Frey, “A review of factors governing exposure to PM5, ultrafine particles and black carbon in Asian transport microenvironments,” Atmospheric Environment, 187:301-316 (2018).
  127. Frey, H.C., “2018 Critical Review: Trends in Onroad Transportation Energy and Emissions,” Journal of the Air & Waste Management Association, 68(6):514-563 (2018).  DOI: 10.1080/10962247.2018.1454357.  50 pages.
  128. Tanvir, S., H.C. Frey, and N.M. Rouphail, “Effect of Light Duty Vehicle Performance on a Driving Style Metric,” Transportation Research Record, 2672:67-78 (December 2018).
  129. Che, W., H.C. Frey, Z. Li, X. Lao, A.K.H. Lau, “Indoor Exposure to Ambient Particles and Its Estimation Using Fixed Site Monitors,” Environmental Science and Technology, 53(2):808-819 2019).
  130. Bunds, K.S., Casper, J.M., Frey, H.C., & Barrett, M. “Air pollution at College Football Games: Developing a Methodology for Measuring Air Pollutant Exposure in a Sport Event Microenvironment,” Event Management, 23(3), 2019, 399-412(14).
  131. Khan, T., and H.C. Frey, “Effect of Air-Conditioning on Light Duty Gasoline Vehicles Fuel Economy,” Transportation Research Record, 2673(5):131–141 (2019).
  132. Yuan, W., H.C. Frey, and N. Rastogi, “Quantification of Energy Saving Potential for a Passenger Train based on Inter-run Variability in Speed Trajectories,” Transportation Research Record, Vol. 2673(5):153–165 (2019).
  133. Yuan, W., H.C. Frey, T. Wei, N. Rastogi, S. VanderGriend, D. Miller, and L. Mattison, “Comparison of Real-World Vehicle Fuel Use and Tailpipe Emissions for Gasoline-Ethanol Fuel Blends,” Fuel, 249:352-364 (August 2019).
  134. Che, W., H.C. Frey, J.C.H. Fung et al., PRAISE-HK: A personalized real-time air quality informatics system for citizen participation in exposure and health risk management, Sustainable Cities and Society, Volume 54 (March 2020).
  135. Frey, H.C., X. Zheng, and J. Hu, “Variability in Measured Real-World Operational Energy Use and Emission Rates of a Plug-In Hybrid Electric Vehicle,” Energies, 13(5), 1140 (March 2020). https://doi.org/10.3390/en13051140
  136. Yuan, W., and H.C. Frey, “Potential for Metro Rail Energy Saving and Emissions Reduction via Eco-driving,” Applied Energy, 268, article 114944, 13 pages. June 15, 2020.  https://doi.org/10.1016/j.apenergy.2020.114944
  137. Wei, T., and H.C. Frey, “Evaluation of the Precision and Accuracy of Cycle Average Light Duty Gasoline Vehicles Tailpipe Emission Rates Predicted by Modal Models,” Transportation Research Record, 2674(7):566-584 (2020). https://doi.org/10.1177/0361198120924006
  138. Wei, T., and H.C. Frey, “Factors Affecting Variability in Fossil-Fueled Transit Bus Emission Rates,” Atmospheric Environment, 233, July 15, 2020, 117613. https://doi.org/10.1016/j.atmosenv.2020.117613
  139. Khan, T., H.C. Frey, N. Rastogi, T. Wei, “Geospatial Variation of Real-World Tailpipe Emission Rates for Light Duty Gasoline Vehicles,” Environmental Science & Technology, 54(14):8968–8979 (2020). https://pubs.acs.org/doi/full/10.1021/acs.est.0c00489
  140. Frey, H.C., D. Gadre, S. Singh, and P. Kumar, “Quantification of Sources of Variability of Air Pollutant Exposure Concentrations Among Selected Transportation Microenvironments,” Transportation Research Record, 2674(9), 395–411. https://doi.org/10.1177/0361198120929336.
  141. CHE, Che, W., A.T.Y. Li, H.C. Frey, K.T.J. Tang, I. Sun, P. Wei, M.S. Hossain, T. Hohenberger, K.W. Leung, A.K.H. Lau, “Factors affecting variability in gaseous and particle microenvironmental air pollutant concentrations in Hong Kong primary and secondary schools,” Indoor Air, 2021;31:170–187. https://doi.org/10.1111/ina.12725
  142. Sandhu, G., H.C. Frey, S. Bartelt-Hunt, E. Jones, “Real-world Activity, Fuel Use, and Emissions of Heavy-Duty Compressed Natural Gas Refuse Trucks,” Science of the Total Environment, Volume 761, 20 March 2021, 143323. https://doi.org/10.1016/j.scitotenv.2020.143323
  143. Hossain, M.S., H.C. Frey, P.K. Louie, and A.K.H. Lau, “Combined effects of increasing O3 concentrations and decreasing NO2 concentrations on short-term air pollution health risk in Hong Kong,” Environmental Pollution, Volume 270, 1 February 2021, 116280. https://doi.org/10.1016/j.envpol.2020.116280
  144. Wei, T., and H.C. Frey, “Sensitivity of light duty vehicle tailpipe emission rates from simplified portable emission measurement systems to variation in engine volumetric efficiency,” Journal of the Air & Waste Management Association, 71:9, 1127-1147 (2021). https://doi.org/10.1080/10962247.2021.1923586
  145. Rastogi, N., and H.C. Frey, “Characterizing Fuel Use and Emissions Hotspots for a Diesel-operated Passenger Rail Service,” Environmental Science & Technology, 55(15), 10633-10644 (2021). https://doi.org/10.1021/acs.est.1c00273
  146. Yuan, W., and H.C. Frey, “Multi-scale evaluation of diesel commuter rail fuel use, emissions, and eco-driving,” Transportation Research Part D: Transport and Environment, Volume 99, October 2021, 102995. https://doi.org/10.1016/j.trd.2021.102995
  147. Hossain, M.S., W. Che, H.C. Frey, A.K.H. Lau, “Factors affecting variability in infiltration of ambient particle and gaseous pollutants into home at urban environment,” Building and Environment, Volume 206, December 2021, 108351. https://doi.org/10.1016/j.buildenv.2021.108351
  148. Wei, T., and H.C. Frey, “Intermodal comparison of tailpipe emission rates between transit buses and private vehicles for on-road passenger transport,” Atmospheric Environment, Available online 30 April 2022, 119141, https://doi.org/10.1016/j.atmosenv.2022.119141.
  149. Yuan, W., H.C. Frey, T. Wei, “Fuel use and emission rates reduction potential for light-duty gasoline vehicle eco-driving,” Transportation Research Part D: Transport and Environment, 109, August 2022, 103394. https://doi.org/10.1016/j.trd.2022.103394
  150. Breen M.S., Y. Xu Y, H.C. Frey, M. Breen, V. Isakov. Microenvironment Tracker (MicroTrac) model to estimate time-location of individuals for air pollution exposure assessments: model evaluation using smartphone data. J Expo Sci Environ Epidemiol. 2022 Dec 16. doi: 10.1038/s41370-022-00514-w
  151. Hu, J., H.C. Frey, B.Y. Boroujeni. Contribution of Cold Starts to Real-World Trip Emissions for Light-Duty Gasoline Vehicles. Atmosphere 2023, 14, 35. https://doi.org/10.3390/atmos14010035
  152. Ahn, Kyoungho, Ahmed Aredah, Hesham A. Rakha, Tongchuan Wei, and H. Christopher Frey. 2023. “Simple Diesel Train Fuel Consumption Model for Real-Time Train Applications” Energies 16, no. 8: 3555.
  153. Rastogi, N, H.C. Frey, and T. Wei, “Identifying emissions hotspots and strategies to reduce real-world fuel use and emissions for passenger rail: A spatially resolved approach,” Science of the Total Environment, Volume 896, 165110, October 2023.