The ozone layer in the stratosphere absorbs a portion of the radiation from the sun, preventing it from reaching the planets surface. In particular, the ozone layer absorbs the portion of UV light called UVB, which has harmful effects on human health and damages most animals, plants, and microbes. Ozone absorbs a range of ultraviolet energy, and when an ozone molecule absorbs even low-energy ultraviolet radiation, it splits into an ordinary oxygen molecule and a free oxygen atom. Usually, this free oxygen atom quickly re-joins with an oxygen molecule to form another ozone molecule. Because of this "ozone-oxygen cycle," harmful ultraviolet radiation is continuously converted into heat.

In summary, the ozone layer absorbs UVB radiation from the sun, which is harmful to human health and damages most animals, plants, and microbes.