Causes of Ozone Depletion

High up in the atmosphere, in a region called the stratosphere between 19 and 30 km above the Earth's surface, ozone is constantly being produced and destroyed naturally. This ozone layer filters out UV rays from the Sun and protects life on Earth. Usually there is a fine balance between the build up and loss of ozone. However, in the 1970s it was discovered that man-made chemicals called CFCs were destroying the ozone in the ozone layer.

CFCs contain chlorine which reacts with ozone at the low temperatures high up in the atmosphere. Once the chlorine has broken up one ozone molecule, it is freed to repeat the process again and again, up to 100,000 times. Thankfully, we have banned the use of new CFCs since 1995. However, because CFCs remain in the air for a long time, they will continue to affect the ozone layer well into the 21^st century.

Ozone Depletion

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• UN Information Unit
• US EPA

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• Introduction
• Causes
• CFCs
• Doing Our Bit
• Human Health
• Impacts
• Ozone
• Ozone Hole
• Ozone Layer
• Protection
• UV Radiation

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