Since ozone is a gas that cannot be stored or transported, it must be generated on site. There are three ways ozone can be generated: 1.) corona discharge 2.) ultraviolet light and 3.) cold plasma. Corona discharge is one of the most popular methods of generating ozone for most industrial and residential applications. Corona discharge involves passing oxygen containing gas through an electrical field. The electrical current causes a split in the oxygen molecule, the resulting oxygen atoms attach themselves to an oxygen molecule forming ozone. Ultraviolet light works very much like corona discharge. Ambient air is passed over an ultraviolet light which splits the oxygen molecule which ends in the formation of ozone. Cold plasma method is usually for ozone being used therapeutically. It utilizes an electrical field but feeds a pure oxygen rather than ambient air used in corona discharge