Study Predicts High Ozone with Increased Ethanol

By Published On: April 20, 2007

Burning more ethanol in cars will increase formation of ground-level ozone – an irritating gas known to cause lung damage and worsen a wide variety of respiratory illnesses – according to a study published April 18 by Environmental Science & Technology. “Ethanol is being promoted as a clean and renewable fuel that will reduce global warming and air pollution,” said Mark Z. Jacobson, Stanford University atmospheric scientist and author of the study. “But our results show that a high blend of ethanol poses an equal or greater risk to public health than gasoline, which already causes significant health damage.” The problem is caused by the breakdown products of ethanol in the atmosphere, which more readily promote ozone formation than those of gasoline. Stanford researchers modeled how a shift to ethanol would affect air quality and its impact on human health. Jacobson said they found that Los Angeles, because of its stagnant air masses and large number of vehicles, would suffer the most from use of high-ethanol blends, such as E85, which is 85 percent ethanol. By 2020, if all cars burned E85, the area would experience 120 more deaths a year from air pollution, 650 more hospitalizations, and 1,200 additional asthma-related emergency visits. A California Air Resources Board spokesperson said the agency could not comment because it still was reviewing the study. Ethanol is seen as a key fuel for meeting the governor’s low-carbon fuel standard and reducing emissions of greenhouse gases (Circuit, Jan. 22, 2007). The study came just a week after the U.S. Environmental Protection Agency on April 10 issued rules that will require an increase in the amount of ethanol blended into gasoline. The standard had been 4.5 billion gallons a year. Under the EPA’s new rules, the amount will be phased up to 7.5 billion gallons a year by 2012. The EPA issued the rules to carry out provisions of the 2005 federal energy bill.

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