Ozone-Forming Potential of Reformulated Gasoline

Committee on Ozone-Forming Potential of Reformulated Gasoline

Board on Environmental Studies and Toxicology

Board on Atmospheric Sciences and Climate

Commission on Geosciences, Environment, and Resources

National Research Council

National Academy Press
Washington D.C.



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--> Ozone-Forming Potential of Reformulated Gasoline Committee on Ozone-Forming Potential of Reformulated Gasoline Board on Environmental Studies and Toxicology Board on Atmospheric Sciences and Climate Commission on Geosciences, Environment, and Resources National Research Council National Academy Press Washington D.C.

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--> NATIONAL ACADEMY PRESS 2101 Constitution Ave., N.W. Washington, D.C. 20418 NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competencies and with regard for appropriate balance. The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Bruce Alberts is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. William A. Wulf is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Kenneth I. Shine is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy's purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Bruce M. Alberts and Dr. William A. Wulf are chairman and vice chairman, respectively, of the National Research Council. This project was supported by Contract No. 68D60069 between the National Academy of Sciences and the Environmental Protection Agency. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the organizations or agencies that provided support for this project. International Standard Book Number 0-309-06445-7 Additional copies of this report are available from: National Academy Press 2101 Constitution Ave., NW Box 285 Washington, DC 20055 800-624-6242 202-334-3313 (in the Washington metropolitan area) http://www.nap.edu Copyright 1999 by the National Academy of Sciences. All rights reserved.

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--> Committee on Ozone-Forming Potential of Reformulated Gasoline WILLIAM L CHAMEIDES (Chair), Georgia Institute of Technology, Atlanta, Georgia CHARLES A. AMANN, KAB Engineering, Bloomfield Hills, Michigan ROGER ATKINSON, University of California, Riverside, California NANCY J. BROWN, Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California JACK G. CALVERT, National Center for Atmospheric Research, Boulder, Colorado FRED C. FEHSENFELD, National Oceanographic Atmospheric Administration, Boulder, Colorado JOHN P. LONGWELL, Massachusetts Institute of Technology, Cambridge, Massachusetts MARIO J. MOLINA, Massachusetts Institute of Technology, Cambridge, Massachusetts S. TRIVIKRAMA RAO, New York State Department of Environmental Conservation, Albany, New York ARMISTEAD G. RUSSELL, Georgia Institute of Technology, Atlanta, Georgia CHRISTOPHER L. SARICKS, Argonne National Laboratory, Argonne, Illinois Staff RAYMOND A. WASSEL, Project Director JAMES ZUCHETTO, Senior Staff Officer ROBERT J. CROSSGROVE, Editor KATHRINE IVERSON, Information Specialist MIRSADA KARALIC-LONCAREVIC, Information Specialist TRACIE HOLBY, Senior Project Assistant

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--> Board on Environmental Studies and Toxicology GORDON ORIANS (Chair), University of Washington, Seattle, Washington DONALD MATTISON (Vice Chair), March of Dimes, White Plains, New York DAVID ALLEN, University of Texas, Austin, Texas MAY R. BERENBAUM, University of Illinois, Urbana, Illinois EULA BINGHAM, University of Cincinnati, Cincinnati, Ohio PAUL BUSCH, Malcolm Pirnie, Inc., White Plains, New York PETER L. DEFUR, Virginia Commonwealth University, Richmond, Virginia DAVID L. EATON, University of Washington, Seattle, Washington ROBERT A. FROSCH, Harvard University, Cambridge, Massachusetts JOHN GERHART, University of California, Berkeley, California MARK HARWELL, University of Miami, Miami, Florida ROGENE HENDERSON, Lovelace Respiratory Research Institute, Albuquerque, New Mexico CAROL HENRY, Chemical Manufacturers Association, Arlington, Virginia BARBARA HULKA, University of North Carolina, Chapel Hill, North Carolina DANIEL KREWSKI, Health Canada and University of Ottawa, Ottawa, Ontario JAMES A. MACMAHON, Utah State University, Logan, Utah MARIO J. MOLINA, Massachusetts Institute of Technology, Cambridge, Massachusetts CHARLES O'MELIA, Johns Hopkins University, Baltimore, Maryland KIRK SMITH, University of California, Berkeley, California MARGARET STRAND, Oppenheimer Wolff Donnelly & Bayh, LLP, Washington, D.C. TERRY F. YOSIE, Chemical Manufacturers Association, Arlington, Virginia Senior Staff JAMES J. REISA, Director DAVID J. POLICANSKY, Associate Director and Senior Program Director for Applied Ecology CAROL A. MACZKA, Senior Program Director for Toxicology and Risk Assessment RAYMOND A. WASSEL, Senior Program Director for Environmental Sciences and Engineering KULBIR BAKSHI, Program Director for the Committee on Toxicology LEE R. PAULSON, Program Director for Resource Management

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--> Board on Atmospheric Sciences and Climate ERIC J. BARRON (Co-Chair), Pennsylvania State University, University Park, Pennsylvania JAMES R. MAHONEY (Co-Chair), I T Group, Inc., Washington, D.C. SUSAN K. AVERY, Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado LANCE F. BOSART, State University of New York, Albany, New York MARVIN A. GELLER, State University of New York, Stony Brook, New York CHARLES E. KOLB, Aerodyne Research, Inc., Billerica, Massachusetts ROGER A. PIELKE, JR., National Center for Atmospheric Research, Boulder, Colorado ROBERT T. RYAN, WRC-TV, Washington, D.C. MARK R. SCHOEBERL, NASA Goddard Space Flight Center, Greenbelt, Maryland JOANNE SIMPSON, NASA Goddard Space Flight Center, Greenbelt, Maryland NIEN DAK SZE, Atmospheric and Environmental Research, Inc., Cambridge, Massachusetts ROBERT A. WELLER, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts ERIC F. WOOD, Princeton University, Princeton, New Jersey Staff ELBERT W. (JOE) FRIDAY, JR., Director LAURIE S. GELLER, Program Officer PETER A. SCHULTZ, Program Officer DIANE L. GUSTAFSON, Administrative Assistant ROBIN MORRIS, Financial Associate TENECIA A. BROWN, Senior Program Assistant CARTER W. FORD, Project Assistant

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--> Commission on Geosciences, Environment, and Resources GEORGE M. HORNBERGER (Chair), University of Virginia, Charlottesville RICHARD A. CONWAY, Union Carbide Corporation (Retired), S. Charleston, West Virginia THOMAS E. GRAEDEL, Yale University, New Haven, Connecticut THOMAS J. GRAFF, Environmental Defense Fund, Oakland, California EUGENIA KALNAY, University of Oklahoma, Norman, Oklahoma DEBRA KNOPMAN, Progressive Policy Institute, Washington, D.C. KAI N. LEE, Williams College, Williamstown, Massachusetts RICHARD A. MESERVE, Covington & Burling, Washington, D.C. JOHN B. MOONEY, JR., J. Brad Mooney Associates, Ltd., Arlington, Virginia HUGH C. MORRIS, El Dorado Gold Corporation, Vancouver, British Columbia H. RONALD PULLIAM, University of Georgia, Athens, Georgia MILTON RUSSELL, University of Tennessee, Knoxville, Tennessee THOMAS C. SCHELLING, University of Maryland, College Park, Maryland ANDREW R. SOLOW, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts VICTORIA J. TSCHINKEL, Landers and Parsons, Tallahassee, Florida E-AN ZEN, University of Maryland, College Park, Maryland MARY LOU ZOBACK, U.S. Geological Survey, Menlo Park, California Staff ROBERT M. HAMILTON, Executive Director GREGORY H. SYMMES, Associate Executive Director CRAIG SCHIFFRIES, Associate Executive Director for Special Projects JEANETTE SPOON, Administrative and Financial Officer SANDI FITZPATRICK, Administrative Associate MARQUITA SMITH, Administrative Assistant/Technology Analyst

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--> Other Reports of the Board on Environmental Studies and Toxicology Research Priorities for Airborne Particulate Matter: I. Immediate Priorities and a Long-Range Research Portfolio (1998) The National Research Council's Committee on Toxicology: The First 50 Years (1997) Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion Tests (1997) Carcinogens and Anticarcinogens in the Human Diet: A Comparison of Naturally Occurring and Synthetic Substances (1996) Upstream: Salmon and Society in the Pacific Northwest (1996) Science and the Endangered Species Act (1995) Wetlands: Characteristics and Boundaries (1995) Biologic Markers [Urinary Toxicology (1995), Immunotoxicology (1992), Environmental Neurotoxicology (1992), Pulmonary Toxicology (1989), Reproductive Toxicology (1989)] Review of EPA's Environmental Monitoring and Assessment Program (three reports, 1994-1995) Science and Judgment in Risk Assessment (1994) Ranking Hazardous Waste Sites for Remedial Action (1994) Pesticides in the Diets of Infants and Children (1993) Issues in Risk Assessment (1993) Setting Priorities for Land Conservation (1993) Protecting Visibility in National Parks and Wilderness Areas (1993) Dolphins and the Tuna Industry (1992) Hazardous Materials on the Public Lands (1992) Science and the National Parks (1992) Animals as Sentinels of Environmental Health Hazards (1991) Assessment of the U.S. Outer Continental Shelf Environmental Studies Program, Volumes I-IV (1991-1993) Human Exposure Assessment for Airborne Pollutants (1991) Monitoring Human Tissues for Toxic Substances (1991) Rethinking the Ozone Problem in Urban and Regional Air Pollution (1991) Decline of the Sea Turtles (1990) Tracking Toxic Substances at Industrial Facilities (1990) Copies of these reports may be ordered from the National Academy Press (800) 624-6242 or (202) 334-3313 www.nap.edu

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--> Preface The clean air act requires the use of reformulated gasoline (RFG) in specific areas of the United States with substantial ozone-pollution problems in an effort to make emissions from light-duty motor vehicles (automobiles and small trucks) less ozone forming and less toxic. That act requires RFG to have a minimum oxygen content of 2% (by weight) to promote more-extensive combustion of ozone-forming pollutants. Methyl tertiary-butyl ether (MTBE) and ethanol are two of the most widely used oxygenates that are blended into RFG to attain the oxygen requirement. The U.S. Environmental Protection Agency (EPA) has established emission performance standards for RFG blends based on the mass of emissions of volatile organic compounds. Because ethanol-blended gasoline has a higher volatility than other blends and thus results in increased evaporation of organic compounds, it is difficult for such blends to meet the RFG standards unless the ethanol is blended with special low-volatility gasoline, which is more expensive and not readily available in many markets. Proponents for the increased use of ethanol in RFG believe that the effects of the increased volatility of ethanol blends could be offset by the benefits that might be achieved through a reduction in ozone-forming potential. It is believed that emissions from the use of ethanol blends of RFG are less reactive in the atmosphere. However, EPA has no established method to assess RFG blends on the basis of ozone-forming potential. Some members of Congress have been urging EPA to consider certi-

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--> fying RFG blends based on atmospheric reactivity or ozone-forming potential of the resulting emissions—not on just the mass of emissions as is done now. At the urging of Senator Lugar and others, EPA arranged for this study with the National Research Council (NRC). The Committee on Ozone-Forming Potential for Reformulated Gasoline was formed in 1997 by the NRC in response to the request from EPA. The committee was asked whether the existing body of scientific and technical information is sufficient to permit a robust evaluation and comparison of the emissions from motor vehicles using different reformulated gasolines based on their ozone-forming potentials and to assess the concomitant impact of that approach on air-quality benefits of the use of oxygenates within the RFG program. As part of its charge, the committee was asked to consider (1) the technical soundness of various approaches for evaluating and comparing the relative ozone-forming potentials of RFG blends, (2) technical aspects of various air-quality issues related to RFG assessment, and (3) the sensitivity of evaluations of the relative ozone-forming potentials to factors related to fuel properties and the variability of vehicle technologies and driving patterns. It is important to note that the committee was not asked to consider scientific issues beyond air quality, such as the relative health risks related to human exposure to various blends of RFG and their resulting emissions. Also, the committee was not asked to address the political, economic, and legal ramifications of changing the way that RFG certification is carried out. The committee was generously assisted by many people, including those who presented valuable information and documents during the committee's public sessions: Charles Freed, Susan Willis, and Christine Brunner, U.S. EPA; Dean Simmeroth and Lawrence Larsen, California Air Resources Board (CARB) staff; Dennis Lawler, Illinois EPA; Michael Ward, of Swidler and Berlin; Gary Whitten, Systems Application International; Alan Dunker, General Motors; Cal Hodge, Oxygenated Fuels Association Technical Committee; Barry McNutt, U.S. Department of Energy; William Carter, University of California at Riverside; Robert Harley, University of California at Berkeley; Howard Feldman, American Petroleum Institute; Charles Schleyer, Mobil. Special thanks are due to Patricia McElroy and Robert Beaver of the University of California at Riverside, and Kevin Cleary of CARB staff who provided valuable assistance in data analysis. Also, Robert Dinneen, Renewable Fuels Association; Stephen Cadle, Coordinating Research Council; and Jose Gomez,

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--> CARB staff, provided very useful information at the committee's request. This report has been reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise in accordance with procedures by the NRC's Report Review Committee. The purpose of this independent review is to provide candid and critical comments that assist the NRC in making the published report as sound as possible and to ensure that the report meets institutional standards for objectivity, evidence, and responsiveness to the study charge. The content of the final report is the responsibility of the NRC and the study committee and not the responsibility of the reviewers. The review comments and draft manuscript remain confidential to protect the integrity of the deliberative process. We wish to thank the following individuals for their participation in the review of this report: David Allen, University of Texas at Austin; Bart Croes, CARB staff; Richard Derwent, Meteorological Office, Berkshire, U.K.; Alan Dunker, General Motors; Thomas Graedel, Yale University; Robert Harley, University of California at Berkeley; Harvey Jeffries, University of North Carolina at Chapel Hill; Douglas Lawson, National Renewable Energy Laboratory; Thomas Peterson, University of Arizona; F. Sherwood Rowland, University of California at Irvine; Marc Ross, University of Michigan; Charles Schleyer, Mobil; Lance Waller, Emory University; and Gary Whitten, Systems Application International. The individuals listed above have provided many constructive comments and suggestions. It must be emphasized, however, that responsibility for the final content of this report rests entirely with the authoring committee and the NRC. The committee was ably assisted by NRC staff, especially Raymond Wassel, James Reisa, James Zucchetto, Laurie Geller, K. John Holmes, Robert Crossgrove, Ruth Danoff, Tracie Holby, and others. Finally, I would like to express my thanks to the members of the committee for their diligent work. This report reflects the committee's consensus response to its charge. WILLIAM CHAMEIDES, CHAIR, COMMITTEE ON OZONE-FORMING POTENTIAL FOR REFORMULATED GASOLINE

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--> Contents     Executive Summary   1 1   Introduction   11     The Ozone-Pollution Problem,   15     History of U.S. Policies to Mitigate Ozone Pollution,   16     Charge to National Research Council Committee,   19     Report Structure,   21 2   Ozone Photochemistry   23     VOC Limitation vs. NOx Limitation,   23     Reaction Pathways of Ethanol and Methyl Tertiary-Butyl Ether,   29     Summary,   31 3   The Concept of Ozone-Forming Potential and Its Quantification   33     Regulatory Application of VOC Ozone-Forming Potential,   34     Operational Definition of Ozone-Forming Potential Using Reactivity,   36     Quantifying Ozone-Forming Potential Using Reactivity,   39     Chemical Mechanisms and Their Development,   41     Reactivity Assessments Using Smog Chambers,   44     Air-Quality Models,   45

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-->     Uncertainties in Species' Reactivities Due to Chemical-Mechanism Uncertainty,   56     Variability of Ozone-Forming Potential with Environmental Conditions,   60     Uncertainties in Relative Reactivities of Motor-Vehicle Emissions,   62     Reactivity for 1-Hr Peak and 8-Hr Averaged Ozone Concentrations,   66     Outstanding Technical Issues in Quantifying Reactivity,   68     Summary,   69 4   Motor Vehicles as a Source of Ozone Precursors   73     Light-Duty Vehicular Emissions by Sources and Regulation,   73     Magnitudes and Trends of Light-Duty Vehicular Emissions,   80     Influence of Driving Patterns on Emissions Variability,   88     Emissions Deterioration and Prospects for Detection,   93     Functionality of Catalysts, Oxygenated Fuels, and Exhaust Emissions,   99     Summary,   100 5   Reformulation of Gasoline   101     Basic Properties,   103     Federal and California Regulation of Gasoline Properties,   107     What is Reformulated Gasoline?   110     Federal Requirements for RFG Under the Complex Model,   118     The California Predictive Model,   119     Performance and Reliability of Complex and Predictive Models,   122     Specification Flexibility and Downstream Control in Federal Phase II RFG,   126     Modeling Evaporative VOC Emissions from RFG for SIP Development,   128     Summary,   130 6   The Effects of Reformulated Gasoline on Ozone and its Precursors   131     What Changes in Motor-Vehicle Exhaust Emissions of VOCs, NOx, CO, or Air Toxics Are Observed in Laboratory Tests When RFGs Are Used?   133

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-->     Have the Changes in Emissions from RFG Blends Indicated by Laboratory Studies Been Observed in Emission Studies Using Tunnels and Remote Sensing of Tailpipe Exhaust?   142     Are There Data to Support Meaningful Analysis of Atmospheric Data to Determine the Effect of RFGs?   154     Have Changes in the Concentrations of Air Toxics or Oxygenates Been Observed in the Atmosphere and Can These Changes Be Related to the Use of RFG?   156     Have Changes in the Concentrations of CO Been Observed in the Atmosphere and Can these Changes Be Related to the Use of RFGs?   157     Have Changes in the Concentrations of Ozone Been Observed in the Atmosphere and Can these Changes Be Related to the Use of RFGs?   164     Documentation of RFG Effects in a Future Observational Program,   166     Summary,   169 7   Using Ozone-Forming Potential to Evaluate the Relative Impacts of Reformulated Gasolines: A Case Study   175     Assessing Whether Emissions and Reactivity Differences Are Statistically Significant,   177     Fuels and Emissions Data from the AQIRP Study,   182     Fuels and Emissions Data from the California Ethanol Testing Program,   191     Is There a Difference Between Conclusions Drawn on the Basis of VOC-Mass Emissions and the Reactivity of the Emissions?   196     Analysis Using the Complex and Predictive Models,   198     Summary,   201     References   203 Appendix A   Biographical Information on Committee Members   218 Appendix B   Letter from Senator Richard G. Lugar   223

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--> Appendix C   Equation Set for the Complex Model-Phase II RFG   226 Appendix D   Data on Emissions from Light-Duty Motor Vehicles using Fuels Selected from the Auto/Oil Air Quality Improvement Research Program and the California Ethanol Testing Program   239

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Ozone-Forming Potential of Reformulated Gasoline

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