Free radicals are atoms or molecules with unpaired electrons, an unavoidable occurrence in bio-chemical reactions. There could be no life without free radicals. However, some free radicals are dangerous. The properties of free radicals vary widely. Some are toxic to all living cells, others only to the most vulnerable cells. Singlet oxygen (O1) is a highly reactive free radical that acts as a scavenger of other free radicals. The oxygen reacts with them to render them harmless, thereby protecting cells from damage. Healthy cells have an enzyme coating around them that protects them from the action of oxygen. These enzymes are catalase, reductase, super-oxide dismutase and glutathione peroxidase. Disease microbes have no such coating and are therefore destroyed by oxygen. By this elegant mechanism, ozone distinguishes between friends and foes and attacks only invading pathogens, and cells that have been damaged and infected, thereby losing their coating. The so-called anti-oxidant enzymes are gaining in popularity as nutritional supplements. They have been shown to help protect marginally healthy cells from general free radical damage. Superoxide dismutase, in particular, has helped reduce a variety of disorders; normally it is among the body’s most plentiful enzymes. However, prolonged use of supplements could tend to atrophy the internal biochemical processes that would normally be making those enzymes. In any case, it does not address the cause of the problem, which is oxygen starvation at the cellular level, which causes the cells to be too weak to make the enzymes that protect them.