Assessing Air Pollution Dispersion Models for Emissions Regulation (2023)

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2023 N A T I O N A L C O O P E R A T I V E H I G H W A Y R E S E A R C H P R O G R A M NCHRP RESEARCH REPORT 1058 Assessing Air Pollution Dispersion Models for Emissions Regulation Edward Carr Seth Hartley Chris Holder Sam Pournazeri ICF San Francisco, CA John Zamurs Zamurs and Associates, LLC Albany, NY Chelsea Preble omas Kirchstetter Michael Sohn LBNL Berkeley, CA Subscriber Categories Environment • Planning and Forecasting • Policy Research sponsored by the American Association of State Highway and Transportation Ofcials in cooperation with the Federal Highway Administration

NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Systematic, well-designed, and implementable research is the most effective way to solve many problems facing state departments of transportation (DOTs) administrators and engineers. Often, highway problems are of local or regional interest and can best be studied by state DOTs individually or in cooperation with their state universities and others. However, the accelerating growth of highway transporta- tion results in increasingly complex problems of wide interest to high- way authorities. These problems are best studied through a coordinated program of cooperative research. Recognizing this need, the leadership of the American Association of State Highway and Transportation Officials (AASHTO) in 1962 ini- tiated an objective national highway research program using modern scientific techniques—the National Cooperative Highway Research Program (NCHRP). NCHRP is supported on a continuing basis by funds from participating member states of AASHTO and receives the full cooperation and support of the Federal Highway Administration (FHWA), United States Department of Transportation, under Agree- ment No. 693JJ31950003. The Transportation Research Board (TRB) of the National Academies of Sciences, Engineering, and Medicine was requested by AASHTO to administer the research program because of TRB’s recognized objectivity and understanding of modern research practices. TRB is uniquely suited for this purpose for many reasons: TRB maintains an extensive com- mittee structure from which authorities on any highway transportation subject may be drawn; TRB possesses avenues of communications and cooperation with federal, state, and local governmental agencies, univer- sities, and industry; TRB’s relationship to the National Academies is an insurance of objectivity; and TRB maintains a full-time staff of special- ists in highway transportation matters to bring the findings of research directly to those in a position to use them. The program is developed on the basis of research needs iden- tified by chief administrators and other staff of the highway and transportation departments, by committees of AASHTO, and by the FHWA. Topics of the highest merit are selected by the AASHTO Special Committee on Research and Innovation (R&I), and each year R&I’s recommendations are proposed to the AASHTO Board of Direc- tors and the National Academies. Research projects to address these topics are defined by NCHRP, and qualified research agencies are selected from submitted proposals. Administration and surveillance of research contracts are the responsibilities of the National Academies and TRB. The needs for highway research are many, and NCHRP can make significant contributions to solving highway transportation problems of mutual concern to many responsible groups. The program, however, is intended to complement, rather than to substitute for or duplicate, other highway research programs. Published research reports of the NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM are available from Transportation Research Board Business Office 500 Fifth Street, NW Washington, DC 20001 and can be ordered through the Internet by going to https://www.mytrb.org/MyTRB/Store/default.aspx Printed in the United States of America NCHRP RESEARCH REPORT 1058 Project 25-55 ISSN 2572-3766 (Print) ISSN 2572-3774 (Online) ISBN 978-0-309-69890-0 Library of Congress Control Number 2023940876 © 2023 by the National Academy of Sciences. National Academies of Sciences, Engineering, and Medicine and the graphical logo are trade- marks of the National Academy of Sciences. All rights reserved. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, APTA, FAA, FHWA, FTA, GHSA, or NHTSA endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. NOTICE The research report was reviewed by the technical panel and accepted for publication according to procedures established and overseen by the Transportation Research Board and approved by the National Academies of Sciences, Engineering, and Medicine. The opinions and conclusions expressed or implied in this report are those of the researchers who performed the research and are not necessarily those of the Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; the FHWA; or the program sponsors. The Transportation Research Board does not develop, issue, or publish standards or spec- ifications. The Transportation Research Board manages applied research projects which provide the scientific foundation that may be used by Transportation Research Board sponsors, industry associations, or other organizations as the basis for revised practices, procedures, or specifications. The Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; and the sponsors of the National Cooperative Highway Research Program do not endorse products or manufacturers. Trade or manufacturers’ names or logos appear herein solely because they are considered essential to the object of the report.

e National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, non- governmental institution to advise the nation on issues related to science and technology. Members are elected by their peers for outstanding contributions to research. Dr. Marcia McNutt is president. e National Academy of Engineering was established in 1964 under the charter of the National Academy of Sciences to bring the practices of engineering to advising the nation. Members are elected by their peers for extraordinary contributions to engineering. Dr. John L. Anderson is president. e National Academy of Medicine (formerly the Institute of Medicine) was established in 1970 under the charter of the National Academy of Sciences to advise the nation on medical and health issues. Members are elected by their peers for distinguished contributions to medicine and health. Dr. Victor J. Dzau is president. e three Academies work together as the National Academies of Sciences, Engineering, and Medicine to provide independent, objective analysis and advice to the nation and conduct other activities to solve complex problems and inform public policy decisions. e National Academies also encourage education and research, recognize outstanding contributions to knowledge, and increase public understanding in matters of science, engineering, and medicine. Learn more about the National Academies of Sciences, Engineering, and Medicine at www.nationalacademies.org. e Transportation Research Board is one of seven major programs of the National Academies of Sciences, Engineering, and Medicine. e mission of the Transportation Research Board is to provide leadership in transportation improvements and innovation through trusted, timely, impartial, and evidence-based information exchange, research, and advice regarding all modes of transportation. e Board’s varied activities annually engage about 8,000 engineers, scientists, and other transportation researchers and practitioners from the public and private sectors and academia, all of whom contribute their expertise in the public interest. e program is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transportation, and other organizations and individuals interested in the development of transportation. Learn more about the Transportation Research Board at www.TRB.org.

C O O P E R A T I V E R E S E A R C H P R O G R A M S CRP STAFF FOR NCHRP RESEARCH REPORT 1058 Waseem Dekelbab, Deputy Director, Cooperative Research Programs, and Manager, National Cooperative Highway Research Program Trey Joseph Wadsworth, Senior Program Officer Mazen Alsharif, Senior Program Assistant Natalie Barnes, Director of Publications Heather DiAngelis, Associate Director of Publications Claire Aelion-Moss, Editor NCHRP PROJECT 25-55 PANEL Field of Transportation Planning—Area of Human and Natural Environment Jackie A. Ploch, Texas Department of Transportation, Austin, TX (Chair) Noel Alcala, Ohio Department of Transportation, Columbus, OH Austina Casey, District Department of Transportation, Washington, DC Yoojoong Choi, California Department of Transportation (CALTRANS), Sacramento, CA Sharon Liljenwall, Oregon Department of Transportation, Salem, OR Jane J. Lin, University of Illinois, Chicago, Chicago, IL Dennis A. Randolph, City of Kalamazoo, Kalamazoo, MI Abhilash Vijayan, Sonoma Technology, Inc., Petaluma, CA Christopher Voigt, Virginia Department of Transportation, Richmond, VA Cecilia Ho, FHWA Liaison Christine L. Gerencher, TRB Liaison

NCHRP Research Report 1058 presents state-of-the-art methods and analytical approaches for project-level air quality modeling by reviewing eight air quality models in use for trans- portation project analyses. This report will be of immediate interest to state and regional transportation planners and decision-makers as they seek to improve analytical modeling methods to assess project impacts on air quality. The report provides insights that are essential for stakeholder confidence and regulatory compliance. Transportation projects must pass regulatory tests such as build/no-build (B/NB) evaluations and demonstrate conformity with applicable national ambient air quality standards (NAAQS). Planners and policymakers need appropriate air quality dispersion models for transportation-sector regulatory applications. State departments of transportation (DOTs) conduct project-level air quality analyses to comply with the National Environmental Policy Act (NEPA) and meet transportation con- formity rule requirements where applicable. DOTs are interested in a rigorous and systematic model review and update process for regulatory dispersion models to ensure the models generate credible results. Under NCHRP Project 25-55, ICF was asked to develop a technical report for decision- makers to identify the appropriate air quality dispersion models for transportation-sector regu- latory applications, and to develop a method for evaluating air quality dispersion models for transportation projects. The report (1) specifies procedures to test air quality dispersion models using real-world air quality data (which must include data from tracer studies) for criteria pollutants typically assessed in project-level analysis; (2) applies these procedures to conduct a detailed evaluation of the selected models against air quality field data; (3) based on the results of the analyses, evaluates the strengths and weaknesses of dispersion models for specific regulatory applications for each pollutant; (4) presents comparative analyses (including technical and methodological evaluations) to show why a particular model is the best-performing for those specific transportation applications; and (5) suggests model improvements based on the model assessments and comparative analyses. In addition to the final report, Appendices A–G and a research results PowerPoint presenta- tion are available on the National Academies Press website (nap.nationalacademies.org) by searching for NCHRP Research Report 1058: Assessing Air Pollution Dispersion Models for Emissions Regulation. F O R E W O R D By Trey Joseph Wadsworth Staff Officer Transportation Research Board

Note: Photographs, figures, and tables in this report may have been converted from color to grayscale for printing. The electronic version of the report (posted on the web at nap.nationalacademies.org) retains the color versions. 1 Summary 9 Chapter 1 Background 11 1.1 Objective 11 1.2 Scope of Work 12 1.3 Organization of this Report 13 Chapter 2 Research Approach and Findings 13 2.1 Review and Identify Air Quality Models and Tracer Studies 19 2.2 Design and Conduct a Field Experiment 25 2.3 Assess Model Performance 41 2.4 Develop an Enhanced Model Evaluation Process 46 Chapter 3 Conclusions and Suggested Research 47 3.1 Conclusions 50 3.2 Recommendations 52 3.3 Suggested Research 54 3.4 Research Applications 56 References 58 Acronyms and Abbreviations 59 Appendices A–G C O N T E N T S