The Canadian Stratospheric Ozone Primer

All life on Earth is protected by the ozone layer - an area of the atmosphere characterized by a delicate and fragile chemistry. Human activities, however, are affecting the ozone layer shield that protects all life on Earth from the harmful rays of the sun. Depletion of the stratospheric ozone layer results in increased ultraviolet radiation levels at the Earth’s surface that are harmful to all life.

In the 1970s, scientists realized that chlorofluorocarbons (CFCs) might deplete the ozone layer. However, it was the discovery of a "hole" in the ozone layer over Antarctica that focused world attention on the problem, leading to unprecedented global action.

Scientists keep learning more and more about how the atmosphere works and how it is affected by human activities. They are also learning more and more about the effects of the sun on all of earth’s life forms.

This Primer is designed to help improve your understanding of ozone depletion. It is divided into sections for ease of access.

1. What is the atmosphere?
2. What are the troposphere, stratosphere and mesosphere?
3. What is in the troposphere?
4. How are human activities affecting the atmosphere?

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