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.
Children are especially vulnerable to ozone's harmful effects, as are adults with existing disease.
But even otherwise healthy individuals may experience impaired health from breathing ozone-polluted air. Elevated ozone levels also inhibit plant growth and can cause widespread damage to crops and forests. National Ambient Air Quality Standard. The standard is based on the highest ozone exposure sensitive persons can tolerate. Ozone is not emitted directly but is formed in the atmosphere through a complex set of chemical reactions involving hydrocarbons, oxides of nitrogen, and sunlight.