1.   Ozone is produced by the reaction between oxygen and ultra-violet light.

2.   Low-level ozone is produced by the effects of sunlight on car fumes.

3.   But reducing this smog component increases the ratio of evaporating paint, gasoline and other volatile organic compounds, thereby producing more ozone.

4.   Cars, power plants, gas stations, dry cleaners, oil refineries and paint shops release the precursor pollutants that produce ozone.

5.   Cain said small amounts of ozone are considered healthful, and some devices intentionally produce ozone to remove contaminants from air and water.

6.   High ozone levels also indicate the presence of other chemicals that produce ozone when they react in sunlight.

7.   In a complex reaction, they mix with gases formed by auto and industrial emissions to produce more ozone.

8.   In the presence of sunlight, the nitrogen compounds produce ozone.

9.   Nitrogen oxides can produce ozone, the level of which exceeds federal standards in metro Atlanta in the summer.

10.   Ozone is produced when car exhaust, oil-based solvents and gasoline vapors react with nitrogen oxides in sunlight.