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Preliminary Findings from the Second Texas Air Quality Study (TexAQS II)

Reducing air pollution is one of the most pressing public policy challenges facing the State of Texas. Failure to meet federal air quality mandates will result in significant public health consequences1 and hundreds of billions of dollars in lost economic development for Texas2. Identifying the most effective and efficient approaches to improving air quality requires a sound understanding of the emissions and atmospheric processes that lead to air pollution.

Decades of air quality research, in Texas and elsewhere, have dramatically improved understanding of the local factors that control air quality in urban areas. Increasingly, however, air quality is influenced by more than just local emissions. Regional, continental and even global factors now have a significant influence on air quality in Texas. Identifying the most effective and efficient balance between local, regional and national air quality improvement actions will require a new body of scientific information.

In response to this challenge, researchers from universities, state and federal agencies, private industry, and local governments are joining forces to conduct a major field study to address air quality issues in the eastern half of Texas. Anticipated participants in the study program will include the Texas Commission on Environmental Quality (TCEQ), a consortium of Texas universities, national labs and universities from around the world, and other regional stakeholders. Leadership will be provided by key participants from the University of Texas-Austin, the University of Houston, Texas A&M University, Rice University, Lamar University, the Texas Commission on Environmental Quality, the Texas Environmental Research Consortium, the Texas Air Research Center, the National Oceanic and Atmospheric Administration, and the Department of Energy. The study, planned for a period extending from April 2005 through October 2006, will examine regional ozone formation, transport of ozone and ozone precursors, meteorological and chemical modeling, issues related to ozone formation by highly reactive emissions, and particulate matter formation. It is anticipated that the information from the study will be the scientific basis used for developing State Implementation Plans (SIPs) for ozone (with concentrations averaged over 8 hours), regional haze, and, if necessary, for fine particulate matter (particulate matter less than 2.5 microns in diameter, PM2.5). With the exception of El Paso County in west Texas, all violations of the National Ambient Air Quality Standards are currently for ozone and are located in the eastern half of the state. This same area is home to the majority of the state’s business activity and population and is often downwind of major source areas in the Eastern and Southern U.S..

This effort will be the third air quality study conducted in the state since 1990; the second study conducted with major national participation, and the first study to have an emphasis on regional, rather than strictly urban, air quality. The Study will be conducted during an eighteen-month period, from May, 2005, through September, 2006 and will focus on the eastern half of Texas. Meteorological data, pollutant concentration data, and information on transport of pollutants will be collected during the entire 18-month period. The scientific effort will focus on the objectives outlined in this report, giving particular attention to characterizing pollutant transport over regional (~100-1000 km) scales and enhancement of tools used in the regulatory process. This focus is required because of the shift in regulatory emphasis away from the air pollutant concentrations averaged over short periods of time (e.g., the ozone standard with ozone concentrations averaged over one-hour) to air pollutant concentrations averaged over longer time periods (e.g., particulate matter samples collected over 24 hours and ozone concentrations averaged over eight hours). Longer averaging times mean broader geographical regions will influence air pollutant concentrations. For example, ozone concentrations in the air transported into Texas cities can frequently be in excess of 70ppb and can often reach 80ppb. With the National Ambient Air Quality Standard set at 85ppb, it is critical to identify and quantify the sources of ozone and ozone precursors that lead to elevated regional concentrations of ozone.

Addressing scientific uncertainties and collecting critical measurements over regional scales will present many challenges. The plan presented in this document identifies the methods and strategies that will be used to successfully meet these challenges, as constrained by the resources available to the study.

1Lurmann, F.W., Hall, J.V., Kleinman, M., Chinkin, L.R., Brajer, V., Meacher, D., Mummery, F., Arndt, R.L., Funk, T.H., Alcorn, S.H., and Kumar, N., “Assessment of the Health Benefits of Improving Air Quality in Houston, Texas”, Final report by Sonoma Technologies to the City of Houston (STI-998460-1875-FR), November, 1999.

2Perryman Group, Report to Texas Conference of Urban Counties, "The importance of maintaining a proper state implementation plan (SIP) to address air quality issues in Texas: An economic and fiscal impact assessment", November, 2002, available at:

This page was last updated November 15, 2006

2000 Center for Energy and Environmental Studies