Ozone Layer

High up in the atmosphere, there is a thin layer of a special gas called ozone. This ozone layer acts like a sunscreen for the whole planet. It absorbs most of the Sun's harmful ultraviolet rays before they can reach us. Without the ozone layer, life on Earth would be in serious danger.

What Ozone Is

Regular oxygen molecules have two oxygen atoms. Ozone is special because it has three oxygen atoms. The ozone layer is found in the stratosphere, about 10 to 30 miles above Earth. Even though it is called a layer, the ozone is spread very thin. If you compressed it, it would be only about as thick as two pennies.

The Ozone Hole

In the 1980s, scientists discovered a hole forming in the ozone layer over Antarctica. It was caused by chemicals called CFCs that were used in refrigerators and spray cans. Countries around the world agreed to stop using CFCs. Since then, the ozone hole has been slowly healing. It is one of the greatest environmental success stories.

Fun Facts

• The ozone layer blocks about 97 to 99 percent of the Sun's harmful ultraviolet radiation.
• CFCs can last in the atmosphere for over 100 years, so the ozone layer will take decades more to fully heal.
• The ozone hole over Antarctica is about as big as North America.

Did You Know?

The agreement to protect the ozone layer is called the Montreal Protocol, signed in 1987. It has been called the most successful environmental treaty ever. Scientists estimate the ozone layer should fully recover by about 2066. It shows that when the whole world works together, we can fix big problems!