ARB Research Seminar

This page updated July 23, 2013

Influence of Highly Variable Spatial and Temporal VOC Emissions in Houston Texas on 1-hr and 8-hr Ozone SIP Modeling

Harvey Jeffries, Ph.D., Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina, Chapel Hill

March 24, 2009
Cal EPA Headquarters, 1001 "I" Street, Sacramento, CA



It is now clearly understood that volatile organic compound (VOC) emissions events from large petrochemical production and refining facilities along the Houston Ship Channel have been the primary cause of very high 1-hr ozone mixing ratios observed at a surface monitoring stations in and around Houston.

More than $50 million in research, field programs, and modeling has been invested in this problem since 2000. New rules and regulatory monitoring have been implemented to address these problems and industries have invested in infrared cameras capable of detecting "events," unknown fugitive sources, and loading and shipping operational losses of highly volatile organics, all in an effort to mitigate the rapid ozone formation that often, but not always, occurs after such releases. Many parties believed that the shift from 1-hr to 8-hr ozone standard would ameliorate this problem and that future state implementation plan (SIP) focus would turn more to "background ozone."

My group's work at the University of North Carolina has instead shown that the current SIP modeling paradigm is basically incapable of effectively dealing with these phenomena.  Analysis of observational data and multiple modeling episodes over three years and application of advanced pseudo-plume process analysis of 4-km and 1-km CAMx modeling episodes illustrate the complexity of representing these dominate features and reveal the extreme difficulty of using standard SIP modeling tools to support effective policies.  This work also suggests that anywhere there is the potential for rapid ambient atmospheric VOC compositional change, there will be similar transient high ozone events created. The limited spatial and temporal character of this high ozone may result in its having a low frequency of detection by typical urban ozone monitoring networks.

A question to ponder is to what extent do the source behaviors and atmospheric processes identified in Houston occur in California communities with similar source categories?

Speaker Biography

Harvey Jeffries has been a Professor of Atmospheric Chemistry in the Department of Environmental Sciences and Engineering in the Gillings School of Global Public Health at the University of North Carolina, Chapel Hill (UNC) since 1971. Dr. Jeffries teaches graduate courses on atmospheric chemistry and photochemical modeling.

Professor Jeffries research interests focus on gas-phase atmospheric chemistry, specializing in volatile organic compound photo-oxidation with oxides of nitrogen to produce ozone, and the mathematical modeling of urban air chemistry, specifically, the development of numerical simulation models of photochemistry that become components of large scale Eulerian models incorporating meteorological and emissions sub-models. Dr. Jeffries has performed photo-chemical experimental and simulation research in smog chambers for 40 years and has been the lead investigator in the creation and implementation of a new photochemical reaction simulation methodology and model analysis methodology used to investigate models in state regulatory applications. Now in collaboration with researchers from the UNC School of Medicine, Professor Jeffries is conducting gas-phase and particle experiments to test air quality toxicity effects on human lung cells using newly designed exposure systems.

Dr. Jeffries has also been active in using these models to plan public policy for air pollution control. Dr. Jeffries was a scientific advisor to the North Carolina State regulatory agency for the 1-hour ozone non-attainment modeling for the North Carolina's State Implementation Plan (SIP).  Dr. Jeffries was in 2000-2003 a scientific advisor to the Business Coalition for Clean Air Appeal Group for the Houston Texas 1-hour ozone non-attainment modeling. He was a member (1996-2005) of the US EPA’s Science Advisory Council, Air Quality Modeling Subcommittee, and a member since 1996 of the California Air Resources Board's Reactivity Scientific Advisory Committee.  Dr. Jeffries was a founding member (1998) of the Reactivity Research Working Group, a public/private research coordinating effort involving US EPA, academia, and industry.  He is a member (since 1999) of the Research Advisory Committee for the Texas Air Research Center at Lamar University in Beaumont.  He was a member (2002-2005) of the Science Advisory Committee of the Texas Environmental Research Consortium operated by the Houston Advanced Research Center.  Dr. Jeffries was a member (1995-1997) of the US EPA’s FACA Subcommittee for the Implementation of New Standards for Ozone, PM, and Regional Haze.  He received an Exceptional Leadership Award from the US EPA (1997) as Co-Chair of Science and Technical Workgroup for this FACA Subcommittee.  Professor Jeffries received the 2003 UNC School of Public Health Bernard G. Greenberg Alumni Endowment Award for excellence in teaching, research, and service. He is a member since 2006 of the National Urban Air Toxics Research Center Science Advisory Panel.  In 2007 Professor Jeffries was awarded a Doctor of Science (Honoris Causa) Degree from Eckard College, St. Petersberg Florida for his contributions to science and public service.

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