VOC stands for Volatile Organic Compound. VOCs are hydrocarbons. This means they are made up of hydrogen and carbon. VOCs are created mostly by cars, but also by industries that burn fossil fuels, such as a coal-burning power plant. Other sources of VOCs include drying paint, charcoal lighter fluid, aerosol cans, motor boats, lawn mowers, and nail polish remover.
Sunlight is the third component.
The rays in sunlight cause the nitrogen oxides and VOCs to mix together. When these chemicals combine, they form ozone. Air currents then scatter this ozone all over the Lake Michigan region, where we all breathe it. It reacts chemically with plants, rubber, and the tissues of living creatures - including you. In fact, kids and elderly people are affected the most.