Figure 6-1

The Decision Tree illustrates the steps taken in an effort to quantify and compare the ozone-forming potential of various RFG blends. The figure indicates the types of findings at each step that resulted from the committee's considerations of the currently available observations that are pertinent to the reduction of ozone concentrations and other air-quality issues. When comparing different RFG blends, such as a blend containing ethanol versus a blend containing MTBE, it is desirable to account for as many differences as possible between the RFG blends.

  • What changes in motor-vehicle exhaust emissions of VOCs, NOx, CO, or air toxics are observed in laboratory tests when RFGs are used?
  • Have the changes in emissions from RFGs indicated by laboratory studies been observed in emissions studies using tunnels and remote sensing of tailpipe exhaust?

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