A recent study from the Environmental Science and Technology journal raises some new concerns about ethanol-based E85 (85% ethanol, 15% gasoline) which can be used in automobiles. The study finds that if much of the country's fuel supply would switch from gasoline to E85, the number of deaths from respiratory failure (due to ozone) in the United States would rise from 4,700 people a year to nearly 4,900 per year.

"It's not green in terms of air pollution," said study author Mark Jacobson, a Stanford University environmental engineering professor and author of the study. "If you want to use ethanol, fine, but don't do it based on health grounds. It's no better than gasoline, apparently slightly worse."

Jacobson used computer models to determine the effects of an increased use of ethanol in automobiles and how they would impact air pollution. The models determined than an increased reliance on E85 would result in increased smog levels -- especially in Los Angeles and major cities in the Northeast.

Jacobson contends that the increase in smog levels is due to the fact that more hydrocarbons are released into the atmosphere from the combustion of ethanol than from gasoline. Jacobson also notes that ethanol produces less nitrogen oxide which most often is a positive side effect. However, in smog-filled areas like Los Angeles the decreased nitrogen oxide levels can be harmful to the atmosphere.

Matt Hartwig, a spokesman for the Renewable Fuels Association, says that he respect's Jacobson's work but takes issues with some of his findings and methodology. Hartwing notes that when using real-world data instead of computer models "ethanol is a greener fuel than gasoline."

President Bush laid out plans earlier this month for the United States to reduce its dependency on gasoline. "We have laid out a plan that will affect greenhouse gases that come from automobiles by having a mandatory fuel standard that insists on 35 -- using 35 billion gallons of alternative fuels by 2017, which will reduce our gasoline uses by 20 percent and halt the growth in greenhouse gases that emanate from automobiles," said President Bush.

Bush's plan would require that auto manufacturers dedicate more of their resources into producing more E85-capable, hydrogen fuel-cell, gasoline-electric hybrid and all-electric vehicles.

Brazil uses sugar cane as the main component for ethanol used in automotive applications. Brazil is also the largest producer of ethanol as a fuel and nearly half of the vehicles running in the country are powered by ethanol. The United States uses corn instead of sugar cane to produce E85 fuel. Less than 3 percent of new vehicles available for purchase in the United States can run on E85.