Recent research with laboratory animals, clinical subjects, and human populations has identified a cascade of adverse health effects from ozone at levels common in the United States. Effects include increased respiratory symptoms, damage to cells of the respiratory tract, declines in lung function, increased susceptibility to respiratory infections, and increased risk of hospitalization and early death. Short-term exposures to ozone can cause a decline in lung function, including rapid breathing, decreased lung volumes and flow, and increased twitchiness of the airways. Exposure early in life may lead to acceleration in the decline of lung function that is a normal process of aging. Respiratory symptoms can include coughing, throat irritation, shortness of breath, and pain on taking a deep breath.
Asthmatics can experience wheezing, a hallmark of an asthma attack.
When children with allergies and asthma are exposed to ozone, they can be more responsive to allergens that can trigger an asthma attack. Ozone triggers an inflammation response in the cells lining the lungs, causing them to rupture and leak. Repeated exposures may lead to structural changes in the respiratory tract including increased production of fibrous tissue associated with lung scarring. Ozone compromises the lungs' natural defense mechanisms, increasing susceptibility to respiratory infections such as colds, flu, and pneumonia. Short-term exposures are also associated with an increase in daily mortality, and increased hospital admissions and emergency department visits for respiratory causes.