Environmental Health Sciences Center

Ozone is a highly reactive form of oxygen. In the upper atmosphere, ozone forms a protective layer that shields us from the sun’s ultraviolet rays. At ground level, ozone is a harmful air pollutant and a primary constituent of urban smog.

Ozone is produced when air pollutants from automobile emissions and manufacturing operations interact with sunlight. Long-term exposure to high concentrations of ozone can cause a significant reduction in lung function, inflammation of the airways, and respiratory distress.

Asthma is an inflammatory disease of the lung. This inflammatory process can occur along the entire airway from the nose to the lung. Once the airway becomes swollen and inflamed, it becomes narrower, and less air gets through to the lung tissue. This causes symptoms like wheezing, coughing, chest tightness, and trouble breathing.

During an asthma attack, the muscles around the airways tighten up and the asthma symptoms become even worse than usual.