The EPA publishes the following about Ozone:
Breathing air containing ozone can reduce lung function and increase respiratory symptoms, thereby aggravating asthma or other respiratory conditions. Ozone exposure also has been associated with increased susceptibility to respiratory infections, medication use by asthmatics, doctor visits, and emergency department visits and hospital admissions for individuals with respiratory disease. Ozone exposure may also contribute to premature death, especially in people with heart and lung disease. High ozone levels can also harm sensitive vegetation and ecosystems.
The summary below of proposed rule changes was entered into the federal register on January 19, 2010 by the EPA