NERL Research Abstract EPA's National Exposure Research Laboratory GPRA Goal 1 - Clean Air Significant Research Findings North American Research Strategy for Tropospheric Ozone State-of-Science Tropospheric Ozone Assessment Purpose The North American Research Strategy for Tropospheric Ozone (NARSTO) is a collaborative public and private sector endeavor to define and implement a research strategy to further understand the science of tropospheric ozone, to identify and fill existing critical research gaps, and to demonstrate the relevance of the science to policy and regulatory requirements. NARSTO's first major project was to initiate a state-of-science assessment for tropospheric ozone. This was the first assessment since a similar assessment was conducted by the National Research Council in 1991. The assessment was to describe the current state-of-science as well as to highlight its relevance to policy makers in the United States, Canada, and Mexico. NERL scientists and managers played key roles in the initiation and production of this assessment. Research The approach that NARSTO took to accomplish this task was a dual-track Approach project. On the first track, a series of Critical Review (CR) papers was commissioned, to be authored by recognized experts in the component areas of tropospheric ozone and related science. The CR papers would span the horizon of ozone science, including trends assessment, monitoring and measurement methods, insights from field experiments, atmospheric chemistry and modeling, and source emissions. The goal for these papers was publication in a special NARSTO issue of an established peer-reviewed journal that would constitute the fundamental and applied science portion of the assessment. On the second track, a NARSTO Synthesis Team was established to write an Assessment Document that would relate the current scientific understanding to the needs of air quality managers in North America. The members of this Team were drawn from the various constituent communities of NARSTO, including the research community (government, industry, academia, and consultants), the air quality management community (national, state/local agencies), and the greater North American community (Canada, Mexico). National Exposure Research Laboratory - September 2000 ------- Major The NARSTO ozone assessment includes many significant findings. Findings . Ozone concentrations appear to be decreasing, or remaining constant in most areas of North America, despite rapid population increases in many areas. The largest decreases have been observed in the Los Angeles, New York, and Chicago metropolitan areas. Decreases in urban ozone concentrations over the last decade are likely associated, at least in part, with decreases in mobile source emissions. Ozone production can be limited by nitrogen oxides (NOx) or volatile organic compound (VOC) availability, and these limitations vary as functions of space and time. Extensive evaluation is generally required to determine optimal emission reduction conditions. • Natural VOC emissions are now known to influence ozone production over a significant fraction of the North American continent. Despite significant scientific and technological modeling advances over the past decade, the ability of air quality models to simulate observed surface ozone concentrations has not improved substantially when measured by traditional metrics of operational performance. In general, the reliability of air quality models remains ill-defined. Some studies suggest that the new 8-hour U.S. ozone standard will result in widespread non-attainment in rural areas, implying further departure from the local emission-reduction strategies of past decades, and require the development of a much more regional observation and analysis structure. The iterative use of emissions-based air quality models with diagnostic analyses including observations-based models, has the potential to improve the efficiency and efficacy of air quality decision-making. Such a system requires the acquisition of reliable and comprehensive data through network monitoring. Research This tropospheric ozone assessment project was made possible by the Collaboration collaboration of many sponsoring and participating groups in North America. *tu1l1. . EPA, Office of Research and Development, National Exposure Research Publications Laboratory, was a major sponsor and participant in this 3-year project. Participation included federal, state/provincial, and local governments, as well as industry groups such as the electric utility, oil, and automobile industries, universities, consultants, and others. The principal documents constituting the assessment include: Schere, K.L., Hidy, G.M., Singh, H.B. (Eds). Special Issue: The NARSTO assessment-critical reviews. Atmospheric Environment 34: 12-14, 2000. North American Research Strategy for Tropospheric Ozone. NARSTO: An Assessment of Tropospheric Ozone Pollution: A North American Perspective. NARSTO Publications, Pasco, WA. 2000. (http://www.cgenv.com/Narsto/). National Exposure Research Laboratory - September 2000 ------- Future NARSTO's next major assessment project will deal with fine particulate matter Research jn North America. In addition, a revised research strategy is being drafted for ozone and fine particulate matter, taking into account the lessons learned from the tropospheric ozone assessment. Inquiries concerning NARSTO tropospheric ozone assessment may be directed to: Kenneth L. Schere U.S. Environmental Protection Agency National Exposure Research Laboratory (MD-80) Research Triangle Park, NC 27711 Phone: (919)541-3795 E-mail: schere.kenneth@epa.gov National Exposure Research Laboratory - September 2000 ------- |