THOSE machines produce ozone which is a oxygen molecule.
It is a colorless unstable toxic gas with a noticeable odor and powerful oxidizing properties. It is formed from oxygen by electrical discharges or ultraviolet light. It differs from normal oxygen (O2) in having three atoms in its molecule (O3).
If this stuff can rust metal in just days think about what it is doing to the lungs of a human. The damage is subtle for some. Others suffer distress and have no idea why?