What is Ozone? Ozone (O3), a 3-atom form of oxygen, is a normal trace element in the earth's atmosphere. Like many substances, ozone is beneficial to life and to man, but can also be harmful in excessive concentrations.
How is Ozone Created in Nature? Ozone is naturally created in the atmosphere by the action of ultraviolet light from the sun on the oxygen in the air. A relatively small amount is also formed by high voltage discharge (lightning) during thunderstorms.
What Purpose Does it Serve in Nature?

This ozone layer in the upper atmosphere is critical for earth and typically is 13-16 miles (2.08-25.6 km) above the earth's surface. This upper layer protects life on earth by absorbing short wave length radiation and preventing this radiation from reaching the surface of the earth.

Ozone in the Indoor Air We Breathe Indoor ozone is typically much lower than outdoors. This is because ozone is highly "reactive". This means it breaks down quickly from O3 (ozone) to simple O2 (oxygen) shortly after it is created.
When We Smell Ozone Odor perception for Ozone varies among each individual. Some people can smell levels at 0.020 ppm. Most people can smell a level of 0.030 ppm, which is well below the recommended levels by the FDA of 0.050 ppm.
Ozone Safety Standard Safety levels for indoors are set by the Food and Drug Administration (FDA). The FDA have set the indoor Ozone safety level at 0.050 ppm within a 24 hour day.
Found out if the SilentAir Air Purifier produces safe levels of ozone. SilentAir ozone output test results.

The difference between filtering air and purifying it.