Ethanol is a renewable alcohol fuel hyped as environmentally friendly solution to air pollution. Proponents claim that ethanol burns cleanly and produces less toxic emissions. It is a linchpin in President Bush's plan to reduce gasoline consumption in the United States by 20% with 10 years. The president announced the plan during the State of the Union address in January 2007.

The most common form is ethanol currently available in the US is E10, a mixture of 90% gasoline and 10% ethanol. E10 is used primarily in urban areas that do not meet clean air standards. All vehicles that use gasoline can run on E10 without a modified engine. The California Air Resources Board (CARB) has been considering the impact of ethanol on air quality. So far, CARB seems ambivalent toward ethanol. It recently applied for a waiver from the U.S. Environmental Protection Agency's rule requiring the use of E10 during the winter months.

That is a valid concern according to Dr. Mark Jacobson (http://www.stanford.edu/group /efmh/jacobson), an atmospheric chemist at Stanford University. In the 1970s, Brazil heavily promoted ethanol fuel. At the same time, for reasons that are still unclear, air quality deteriorated. Using that knowledge, a NASA research grant for computational development, and a sophisticated atmospheric computer model, he compared two air quality scenarios for the year 2020: a vehicle fleet fueled entirely by gasoline versus a fuel flexible vehicle (FFV) fleet, which should be common by then. FFVs (http://www.e85fuel.com/e85101 /flexfuelvehicles.php) are vehicles that can run on 100% unleaded gasoline or a mixture of gasoline and up to 85% ethanol. The next generation of ethanol is E85, a blend of 85% ethanol and 15% gasoline. It contains approximately 80% less contaminants than gasoline. The National Ethanol Vehicle Coalition (NEVR) (http://www.e85fuel.com) maintains that E85 will reduce greenhouse gas emissions as much as 46%, is non-toxic, water soluble and biodegradable. They claim that the cleaner exhaust will mean less smog and fewer respiratory illnesses. The American Lung Association of the Upper Midwest also endorses E85 as a "Clean Air Choice" (http:/CleanAirChoice.org).

However, Dr. Jacobson's study, "Effects of Ethanol (E85) Versus Gasoline Vehicles on Cancer and Mortality in the United States" (http://pubs.acs.org/cgi-bin/a bstract.cgi/esthag/asap/abs/es 062085v.html), produced results that contradict NEVR's assertions. This is

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