Ethanol-powered vehicles generate more ozone than gas-powered ones

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Washington, December 15 (ANI): A new study has determined that ethanol-powered vehicles generate more ozone than gas-powered ones.

The study, by researchers at Stanford University, indicates that ethanol, which is often promoted as a clean-burning, renewable fuel that could help wean the nation from oil, would likely worsen health problems caused by ozone, compared with gasoline, especially in winter.

Ozone production from both gasoline and E85, a blend of gasoline and ethanol that is 85 percent ethanol, is greater in warm sunny weather than during the cold weather and short days of winter, because heat and sunlight contribute to ozone formation.

But, E85 produces different byproducts of combustion than gasoline and generates substantially more aldehydes, which are precursors to ozone.

"What we found is that at the warmer temperatures, with E85, there is a slight increase in ozone compared to what gasoline would produce," said Diana Ginnebaugh, a doctoral candidate in civil and environmental engineering, who worked on the study.

"But even a slight increase is a concern, especially in a place like Los Angeles, because you already have episodes of high ozone that you have to be concerned about, so you don't want any increase," she added.

But, it was at colder temperatures, below freezing, that it appeared the health impacts of E85 would be felt most strongly.

"We found a pretty substantial increase in ozone production from E85 at cold temperatures, relative to gasoline when emissions and atmospheric chemistry alone were considered," Ginnebaugh said.

Although ozone is generally lower under cold-temperature winter conditions, "If you switched to E85, suddenly you could have a place like Denver exceeding ozone health-effects limits and then they would have a health concern that they don't have now," she explained.

The problem with cold weather emissions arises because the catalytic converters used on vehicles have to warm up before they reach full efficiency.

So, until they get warm, a larger proportion of pollutants escapes from the tailpipe into the air.

There are other pollutants that would increase in the atmosphere from burning E85 instead of gasoline, some of which are irritants to eyes, throats and lungs, and can also damage crops, but the aldehydes are the biggest contributors to ozone production, as well as being carcinogenic. (ANI)

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