It can oxidize bacteria, molds, fungi, mites and other pathogens, e.g. some viruses and many other chemical compounds. Also popular is lastly ozone odor removal.
Effect of ozone in principle consists in rapid oxidation. Encountering various pollutants floating in the air, ozone comes with them in the chemical reaction causing their oxidation. The third oxygen atom in its molecule makes ozone is very reactive (active chemical) - easily reacts with the particle of pollutants such as odors and pathogens. It decomposes them in less complex, and usually less harmful molecules. The remaining ozone itself decays back to oxygen, which makes it very environmentally friendly. Cleaning of rooms with the use of ozone is much more effective than using traditional chemical agents.
It is interesting that ozone occurs naturally in the environment, appearing as a result of lightning strikes which occur during thunderstorms. In fact, "fresh, clean, spring" smell that we notice after a storm often is related with the action of ozone. Most, however, we hear of ozone in context of "ozone layer" that surrounds our planet above the earth's atmosphere and protects us from harmful ultraviolet radiation. Here ozone is created by the UV rays of the sun.