Ozone is a complex form of oxygen.
This type of ozone is good for us. Ozone Pollution in the air we breathe is the enemy. Called ground-level ozone, this pollution forms in the lower atmosphere in warm weather. A hot, sunny, still day is the most dangerous kind for ozone pollution. That's when the sun bakes unburned gases from tailpipe emissions, fuel evaporation and smokestacks to create ozone.