Drivers may get some help from automakers, who are looking at designs for gasoline and diesel power plants that would reduce harmful emissions. Such vehicles may be widely available by 2008. When ozone levels are high at ground level, it can stunt plant growth. At higher levels, it can break down the cells and tissues of animals and humans. Ozone forms when sunlight and heat cause a chemical reaction.
Conditions are ideal on hot, sunny days with little wind.