For those interested in preserving the environment, this week brings sobering news about ethanol. This fuel, distilled from plants like corn and switchgrass, has been widely touted as an eco-friendly, clean-burning alternative to gasoline. But a study published this week in the journal Environmental Science and Technology suggests that replacing our current gas-guzzlers with vehicles that burn ethanol would actually increase pollution and damage human health. Stanford scientist Mark Jacobson used a computer model to predict air quality in the year 2020, when ethanol-powered cars are expected to be widely available in the US. His simulation showed, among other things, that cars that burn a blend of 85 percent ethanol will significantly increase ozone, a prime ingredient in smog. So in a world where the cars run on switchgrass juice, more people will get asthma, more people will be hospitalized with respiratory distress, and more people will die from breathing in ozone than if we'd kept on driving our gas-powered clunkers.