The ozone layer was that part of a planet's atmosphere which contained higher than usual concentrations of ozone. Ozone was a chemical compound formed of three oxygen atoms. Even the small concentrations of ozone presented in the ozone layer were vital to life on most planets because of the particle's ability to block ultraviolet radiation, which could be harmful to biological life.
The planet Aldea suffered damage to its ozone layer from the long-term use of its planetary defense system. The resulting radiation poisoning rendered the Aldeans sterile and threatened to destroy their civilization. (TNG: "When The Bough Breaks")
|Structure and layers of an atmosphere|
| Planetary: Troposphere • Stratosphere • Thermosphere • Exosphere |
Ozone layer • Ionosphere • Magnetosphere • Mesosphere
|Solar: Photosphere • Chromosphere • Corona|