You can prove it with your own meters.
You’ll need a body voltage kit and our video walkthrough. We like the Safe Living Technologies® Body Voltage Home Test Kit. This will let you test EMF levels in and out of the sauna, plus it will show you how those levels affect body voltage.
You’ll need a pulsing light meter. We like the Safe Living Technologies OFC-1.
You’ll need an irradiance meter that works across the light therapy band of 600–1000 nm. We like the Megger PVM 210 Irradiance Meter, which has a range of 400–1100 nm.
You can use a standard air thermometer, just make sure it measures temperatures up to 120 °F.