I can't smell ozone in my sauna any more. Is the ozonator still producing ozone?

Do not test by smell

People who are around ozone daily stop noticing the sharp, sulphurous smell, so a weak smell does not mean the generator has failed, and a strong one is not a measurement. Ozone is also toxic to the lungs, and our guidance is not to lean in, put your face into the cabinet or open the doors while ozone is running — which is exactly what a smell test asks you to do.

Bear in mind too that the generator stops producing five minutes before the session ends, and ozone’s half-life in the hot sauna is roughly 10 to 20 minutes. Little is left when you open the doors, which is by design.

The glove test

1. Confirm the oxygen concentrator is switched on and running, and that no pipe between the concentrator and the sauna is pinched, blocked or disconnected. A test run with the concentrator off tells you nothing.
2. With the ozone on, hold a latex glove in front of the ozone outlet for a few seconds.
3. Ozone is a strong oxidant — it strips electrons from whatever it meets — and latex is not an ozone-resistant material, so a hole should appear in the glove. No hole after a fair exposure means no meaningful ozone output.

What a positive test does and does not tell you

A hole in the glove means the generator is producing ozone. It does not tell you how much, and it is not a calibration.

What the generator should be doing is settled: 500 mg/h at full output, stepped by 10 per cent at each of the ten display levels, on a constant 2 l/min oxygen feed, giving about 47 ppm across the whole air volume inside the sauna. Confirming that in the field is another matter — measuring real output needs a laboratory-grade analyser, which is worth remembering if anyone offers to “calibrate” your generator.

If the glove shows no damage, work through the no-ozone checks: the concentrator, the pipework, and the internal fitting that holds the ozone pipe.