Ozone

Ozone is a chemical compound consisting of three oxygen atoms. It is represented by the symbol O₃.

It is unstable at standard temperatures and pressures, and a powerful oxidizer. At the earth's surface it occurs naturally as a result of electrical discharges, most prominently, lightning. It is also created by man-made sparks, such as in an electrical motor. In the upper atmosphere it serves a very important function (from our perspective), by acting to filter out most of the sun's ultraviolet radiation. This ozone layer has been threatened in recent decades by the release of chlorofluorocarbons, which act as catalysts to break down the O₃ molecules.

Some air freshening devices generate ozone to aid in the breakdown of airborne chemicals.