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Facts on the Depleting Ozone Layer

The ozone layer is a layer of gas in the atmosphere that helps to shield the Earth from harmful sun radiation. It is important to preserving life on Earth and has proven to be unexpectedly fragile. The harm inflicted on the ozone layer by human activity is slowly being repaired, since industrialized countries banned the use of the chemicals that were destroying it by 1996, but it still serves as an example of the kind of unwitting hurt people can carelessly do to their planet and thus themselves.

The Definition
- Ozone is what people call a blue, strong-smelling molecule with three oxygen atoms. Normal oxygen has only two atoms and no color or smell. The highest numbers of ozone molecules occur in the stratosphere, that layer of air that is 10 to 50 kilometers above the Earth, but it is not very common even then. Only 3 out of every 10 million air molecules are ozone. They are still powerful, absorbing radiation from the sun, especially ultraviolet radiation, and keeping it from reaching Earth.
Ozone Levels
- There are many natural processes that affect the concentration of ozone molecules in the stratosphere. The changing of the seasons, variations in the intensity of the sun and latitude over the Earth all impact the ozone layer. The creation and destruction of ozone molecules is natural and on-going. In the 20th century, though, it was discovered that chlorines introduced into the atmosphere by humans were destroying ozone faster than it could be replaced.
The Dangers of Chlorine
- One atom of chlorine is enough to destroy 100,000 ozone molecules. Normally, chlorine from the Earth's surface does not reach the stratosphere. Even that which is put into the air by industrial plants and volcanoes gets combined with rain before it can get that high up. One exception to this is the chlorine found in chlorofluorocarbons, man-made -- now illegal -- chemicals once used in many applications such as refrigerants, solvents, soil fumigants and aerosol sprays. These molecules rise through the atmosphere and do not break up until they are subjected to strong ultraviolet radiation. That is when they release their chlorine.
Why People Need Ozone
- For humans and animals, more ultraviolet radiation means an increase in skin conditions like cancer and eye conditions like cataracts. Perhaps its most grave effect is on the phytoplankton, tiny sea plants fed on by countless other creatures. A reduction in this basic food source would have repercussions all the way up the food chain. Other water creatures such as fish, crabs and frogs experience reduced reproduction rates as a result of overexposure to ultraviolet rays.

Nature