Ozone is a form of molecular oxygen that consists of three oxygen atoms linked together.
But ozone at ground level is a noxious pollutant. It is the major component of smog and presents this country's most intractable urban air quality problem. Ozone is a severe irritant. It is responsible for the choking, coughing, and stinging eyes associated with smog. Ozone damages lung tissue, aggravates respiratory disease, and makes people more susceptible to respiratory infections.