Ozone (O3) is the combination of two oxygen molecules (O2) with another singlet oxygen molecule.  That extra molecule breaks loose after a short period of time and attaches itself to weak and damaged cells, destroying viruses and pathogens so they can be easily eliminated from the body.  It can increase the flexibility of red blood cells, allowing oxygen levels to stay elevated longer, and accelerates the TCA cycle, which is important in the glycolysis of carbs for energy.  The antioxidant enzyme system becomes more efficient and helps break down petrochemicals.
A lot of illnesses and other problems exist in low oxygen environments, things like fungi, viruses, yeasts and bacteria.  These toxins die and are more readily detoxed when exposed to high oxygen environments that ozone can create.
Ozone has been used medically since the early 1900s.  It was legal for use by medical professionals in the US until the medical establishment banned it in favor of far more profitable synthetic petrochemical drugs.  It is still used by doctors and ozone treatments are legally used in Italy, Russia, Germany, Malaysia, Cuba, Mexico and more.