A study researchers at Stanford University concludes that cars running on ethanol instead of gasoline pose an equal or even greater health risk:
Jacobson simulated widespread ethanol usage with a mainframe computer, but focused his attention to the Los Angeles area because of its high pollution and population density. His computer model combined the effects of tailpipe emission chemicals with temperatures, sunlight, clouds and precipitation. He also calculated wind effects and the ethanol’s reaction with other airborne chemicals.
The simulation calculated two future scenarios set in the year 2020 that compared an all gasoline vehicle fleet versus one fueled by ethanol 85 which is a blend of 85 percent ethanol and 15 percent gasoline. In the E85 scenario, the levels of the carcinogens benzene and butadiene were reduced, but two others formaldehyde and acetaldehyde rose. Ozone also significantly increased in some parts of the country.
The researchers calculated the increase in ozon would cause an additional 200 deaths a year, that's 4 percent more than what it would be with gasoline cars.