Ozone is an air quality problem in the summer months when temperature and sunlight are the greatest.
Ozone can lead to reduced lung function, increased respiratory inflammation, coughing, chest pain and nausea. Children are especially at risk from ground-level ozone because they breathe in more air for their body weight than adults and spend more time outdoors in the summer. Until 1997, the nation's ozone standard was 125 parts per billion, measured over one hour. When a monitor in an area exceeded the standard more than once a year, the area did not attain the standard. In July 1997, EPA established a more stringent ozone standard based on health studies addressing longer term exposure.