LOS ANGELES, April 18 (Xinhua) -- Ethanol would have serious health effects if heavily used in cars, producing more ground-level ozone than gasoline, scientists warned.

    "Ethanol is being promoted as a clean and renewable fuel that will reduce global warming and air pollution, 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," said Jacobson, who authored the Stanford University study published Wednesday in the online edition of Environmental Science and Technology.

    The ozone hazards are more evident in low areas like the Los Angeles Basin, said the study.

    Ozone, a key ingredient in smog, can harm lungs, aggravate asthma and impair immune systems when inhaled even at low levels.

    The study determined that a 9-percent increase in ozone-related deaths would occur in Greater Los Angeles and a 4-percent increase nationally by 2020 if a form of ethanol called E85 were used instead of gasoline, according to the study.

    In the Southeast, by contrast, mortality rates would decrease slightly.

    The study used a computer model to simulate air quality in 2020,when ethanol-fueled vehicles are expected to be widely available in the United States, with a focus on Los Angeles.

    "Today, there is a lot of investment in ethanol," Jacobson said. "The question is, if we're not getting any health benefits, then why continue to promote ethanol?"