Ozone and oxygen
Corona discharge versus UV ozone generation
The two common ways to make ozone. Corona discharge uses a high-voltage electrical discharge and produces high concentrations, especially from an oxygen feed. Ultraviolet generation uses a 185 nm lamp to split oxygen and produces much lower concentrations. Therapeutic and industrial equipment uses corona discharge.
Also called CD vs UV ozone, ultraviolet ozone generator
Ultraviolet generation
A lamp emitting at about 185 nanometres photolyses oxygen molecules in air passing over it, and the freed atoms form ozone. It is simple, cheap and self-limiting, because the same lamp’s output also destroys ozone at other wavelengths. It produces very low concentrations, typically a fraction of one percent by mass, and output falls as the lamp ages. It is found in small air purifiers and some water systems.
Corona discharge
An alternating high voltage across a dielectric barrier creates a cold plasma that dissociates oxygen far more efficiently. The Dégremont water treatment handbook gives typical yields of about 3% ozone by mass from an air feed and about 10% from an oxygen feed — one to two orders of magnitude above what a UV lamp achieves. Concentration is controllable, and the feed gas can be chosen.
Why it matters for a sauna
Any device intended to deliver a measured ozone dose has to use corona discharge, because dose control requires a known and adjustable concentration. It is also the only approach compatible with a medical oxygen feed: a UV lamp sitting in an ambient air stream cannot give you one. Our saunas use built-in generators fed from a medical oxygen concentrator.
The trade-off
Corona discharge is sensitive to moisture in the feed gas, which is why feed gas dryness matters and why a wet air feed damages the dielectric over time. UV generation is untroubled by this but cannot reach useful concentrations. Neither approach makes ozone safe to breathe.
Why it matters here
It is a quick way to tell a therapeutic device from an air-freshening gadget: anything built to deliver a measured ozone dose uses corona discharge.