With less oxygen available than they need, cells are unable to make their defensive enzyme shields strong enough, and viruses can invade and force the cell to replicate viruses. As long as the cell maintains this enzyme shield, viruses cannot penetrate them and ozone cannot harm them. Disease microbes have no enzyme shields. When medical ozone is introduced into the area, it attacks microbes without a coating and diseased cells with deficient cell wall enzymes. It oxidizes them, allowing them to be cleared from the body and replaced with new healthy cells.
Free radicals are atoms with unpaired electrons, a natural occurrence in biochemical reactions.
There could be no life without free radicals. The oxygen combines with them to render them harmless, thereby protecting cells from damage. They are not antioxidant at all, but rather are either free radical scavengers, or enzyme enhancers. They have been shown to help protect marginally healthy cells from general free radical damage. However, prolonged use of supplements could tend to atrophy the internal biochemical processes that would normally be making these enzymes.