Ozone is a molecule in the Earth's atmosphere.
An ozone molecule consists of three oxygen atoms. Despite the fact that ozone forms only a small fraction of all the constituents of the atmosphere, it is still an important factor for the continuity of life on planet Earth. Ozone either protects or harms organisms on Earth depending on the height at which it is found. An excess of UV radiation increases the risk of getting skin cancer or ocular diseases. It may also weaken the natural immunity of human beings and animals.