Although improvements have been made through enforcement of the Federal Clean Air Act, air pollution still clogs our nation's skies. In simple terms this is bad ozone. This lower level ozone should not be confused with the ozone layer that forms in the upper atmosphere, which is good ozone. Ozone levels tend to rise when the weather is extremely hot and sunny, with low or no winds. Evaporative chemicals such as gasoline and paint thinners, auto exhaust, and industrial emissions mix in the lower atmosphere, and when they interact with sunlight a photochemical reaction occurs resulting in ozone.
Ozone is a form of oxygen with three atoms instead of the usual two.
You can't see ozone, smell it, touch it, or reach out and grab it. Even though ozone is a colorless gas, that doesn't mean it's harmless. On days when ozone levels are high, people with respiratory problems may be affected the most while doing daily outdoor activities. They may experience shortness of breath more frequently. Young children with asthma problems may need more oxygen on days with higher concentrations of ozone.