Ethanol when burned creates Acetaldehyde,a carcinogen. All blends create more ozone then straight gas."except e85.most vehicles made after 2000.have three way catalytic converters.that emit the same amount of 02 as ethanol. Ethanol also uses huge amounts of water to produce. Pollutes water.Due to nitrogen used to produce corn. In the last few years Iowa has torn up 15 million acres for corn for ethanol.