filled, and identify the types of emission data that would be needed to continuously evaluate the ozone-forming potential of emissions from vehicles using RFG.

It is important to note that the committee was not asked to consider other issues related to the choice and use of various blends of RFG. Therefore, the committee has not addressed issues such as balance of trade, energy and cost requirements for fuel production, domestic sources of fuel versus foreign sources, human health and global environmental impacts, and use of renewable fuels versus nonrenewable fuels. In addition, it should be noted that this report is limited to the scientific and technical aspects of this issue; the possible design or implementation of regulations based on ozone-forming potential are not within the scope of this study.

Report Structure

In response to its charge, the committee's report addresses (1) how the ozone-forming potential of emissions from light-duty motor vehicles might be affected by the use of RFG blends with and without various types and concentrations of oxygenates; and (2) the extent to which current scientific and technical understanding and information are adequate to quantify these effects robustly. Although the focus is on the impacts of RFGs on ground-level ozone concentrations, RFG and the oxygenates added to these gasolines can also have impacts on other air-quality issues (e.g., toxics, carbon monoxide, and particulate matter); these other impacts are mentioned when they are relevant or potentially significant.

To provide a technical foundation for the assessment, the report provides overviews of the photochemistry of ozone, the concept of atmospheric reactivity and ozone-forming potential, motor vehicles as a source of ozone precursors, and RFGs in Chapters 2, 3, 4, and 5, respectively. In Chapter 6, the report assesses the likely magnitude of the air-quality benefits of the federal and California RFG programs (in total) based on observations. Chapter 6 also outlines the characteristics of a measurements program that could more robustly quantify the air-quality benefits and the changes in the ozone-forming potential of vehicular emissions arising from Phase II of the federal RFG program. The committee's assessment of RFG's overall impact on ozone serves as a calibration



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