Ozone (O3) is an allotrope of oxygen, the molecule consisting of three oxygen atoms instead of the more stable diatomic O2.
Ozone is a powerful oxidizing agent.
It is present in low concentrations throughout the Earth's atmosphere.
It has many industrial and consumer applications as well as being used in ozone therapy.
Ozone may be formed from O2 by electrical discharges and by action of high energy electromagnetic radiation.
Certain electrical equipment generate significant levels of ozone.
The highest levels of ozone in the atmosphere are in the stratosphere, in a region also known as the ozone layer between about 10 km and 50 km above the surface.
Here it filters out the shorter wavelengths (less than 320 nm) of ultraviolet light (270 to 400 nm) from the Sun that would be harmful to most forms of life in large doses.