Ozone and oxygen
Ozone concentration (ppm)
Concentration describes how much ozone is present in a gas mixture, as a ratio. Parts per million (ppm) is the usual unit. It is not the same as output (mg/h), and a concentration inside a sealed cabinet is not comparable to a concentration in the room air people breathe.
Also called ppm, parts per million, ozone concentration
A ratio, not a quantity
One part per million means one molecule of ozone per million molecules of gas. Concentration tells you how strong a mixture is; output in mg/h tells you how much is being made. Which of the two you are looking at depends entirely on where the measurement was taken.
Our figure, and what it describes
Salvagente saunas are quoted at about 47 ppm. That is the ozone concentration in the whole air volume inside the sauna, with the generator running at 500 mg/h and the oxygen feed constant at 2 litres per minute. It is not the concentration in the delivery line, which is a far smaller volume. Nor is it a fixed number: it shifts with the user’s size, body structure and weight, since a larger person displaces more of the air inside and presents more skin for the ozone to react with.
Two very different numbers
This is the most confusing thing about ozone specifications, so it is worth stating plainly.
- Inside the cabinet, with the user’s head outside and the neck opening covered, ozone is applied to skin. The figure is about 47 ppm.
- In the room, where staff work all day and the client breathes, ozone is an inhalation hazard. The occupational limits cited by the US Environmental Protection Agency are around 0.1 ppm averaged over eight hours (OSHA) and 0.1 ppm as a ceiling (NIOSH), with the FDA limiting indoor medical devices to 0.05 ppm.
Those numbers are hundreds of times apart because they describe different exposures to different tissue.
Why it matters here
The 47 ppm figure describes the air inside the sauna, not the air in the room around it. Ventilating the treatment room is a separate question from the settings on the display, and the two numbers are not comparable.