With its more complete combustion, it reduces the amount of toxic carbon monoxide emissions. When ethanol is burned, carbon dioxide is also released. It benefits the Earth because plants take in this carbon dioxide. This process helps plants grow and it helps in photosynthesis. Since ethanol has a high octane rating, it helps in the reduction or removal of hydrocarbons.
Hydrocarbons are major contributors to the ozone depletion.
Aromatic hydrocarbons like benzene are toxic to humans and some can cause cancer. Using ethanol to remove or reduce these hydrocarbons reduces their emissions. The more they react with the sun, the more ground level ozone there will be. The moisture and particulate matter already in the air combined with these toxins show up as smog. Smog has damaging effects to plants and causes respiratory problems in humans.