Editing Ozone (section)

===Ultraviolet light===
{{See also|Photochemistry}}
UV ozone generators, or vacuum-ultraviolet (VUV) ozone generators, employ a light source that generates a narrow-band ultraviolet light, a subset of that produced by the Sun. The Sun's UV sustains the ozone layer in the stratosphere of Earth.<ref>{{cite journal |last=Dohan |first=J. M. |author2=W. J. Masschelein |year=1987 |journal=Ozone Sci. Eng. |title=Photochemical Generation of Ozone: Present State-of-the-Art |volume=9 |pages=315–334 |issue=4 |bibcode=1987OzSE....9..315D |doi=10.1080/01919518708552147}}</ref>

UV ozone generators use ambient air for ozone production, no air prep systems are used (air dryer or oxygen concentrator), therefore these generators tend to be less expensive. However, UV ozone generators usually produce ozone with a concentration of about 0.5% or lower which limits the potential ozone production rate. Another disadvantage of this method is that it requires the ambient air (oxygen) to be exposed to the UV source for a longer amount of time, and any gas that is not exposed to the UV source will not be treated. This makes UV generators impractical for use in situations that deal with rapidly moving air or water streams (in-duct air [[sterilization (microbiology)|sterilization]], for example). Production of ozone is one of the [[ultraviolet germicidal irradiation#Potential dangers|potential dangers]] of [[ultraviolet germicidal irradiation]]. VUV ozone generators are used in swimming pools and [[spa]] applications ranging to millions of gallons of water. VUV ozone generators, unlike corona discharge generators, do not produce harmful nitrogen by-products and also unlike corona discharge systems, VUV ozone generators work extremely well in humid air environments. There is also not normally a need for expensive off-gas mechanisms, and no need for air driers or oxygen concentrators which require extra costs and maintenance.