It not only affects people with existing breathing problems, but also can affect healthy children and adults. Persons especially sensitive to ozone exposure are the elderly, infants and children, asthmatics, chronic respiratory patients, pregnant women, smokers, persons with a history of chest discomfort or respiratory allergies, and persons with lung cancer, cardiovascular disease or immune system deficiency. At very low ozone levels, sensitive persons may experience irritation of the eyes, nose, sinuses, throat, and lungs resulting in watery eyes, runny nose, and coughing. At higher ozone levels, persons may experience chest tightness, shortness of breath, pain when breathing deeply, and wheezing. Other less common symptoms are blurred vision, headache, nausea, vomiting, and fatigue.
Ozone also appears to make the lungs more susceptible to bacterial infections.
The odor of ozone is noticeable at low levels. As the level of ozone increases, the ability to smell it may decrease. This is especially true when a person is frequently exposed. A lack of odor and fewer symptoms may falsely give the impression of reduced exposure, even though further damage to health may be taking place. Children may suffer lung irritation but not notice or complain about symptoms.