Ethanol has long been touted as a cleaner-burning alternative to gasoline and it carries the image of an environmentally friendly fuel since it’s derived from plants and plant waste. Experts say replacing gas with ethanol blends will reduce greenhouse gases and help the fight against global warming.

But the more than 200 U.S. refineries in operation or under construction — mostly in a swath from Nebraska and Kansas east into Ohio — also emit thousands of tons of pollutants a year, including nitrogen oxide, a key element of smog.

Increased use of ethanol could raise smog levels about 1 percent in some areas of the country, according to the Environmental Protection Agency.

Read (AP via MSNBC)