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What is Ozone Layer
Ozone Layer
Ozone is a naturally occurring gas found in the atmosphere where it absorbs most of the sun's ultraviolet light - invisible rays which are harmful to both plant and animal life.
Ozone is found throughout the atmosphere including at ground level, but is mostly (about 90%) found in a band called the ozone layer at about 15 - 30 km above the Earth's surface, in the stratosphere, the height at which larger aircraft fly. It is not really a “layer” at all but one of many gases found in the stratosphere.
The ozone layer is essential for life - until it was formed, about a billion years ago, the only life on Earth was at the bottom of the ocean. It is thought that single celled organisms released oxygen through photosynthesis.
The ozone layer became more widely appreciated by the public when it was realized that certain chemicals mankind manufactures, called chlorofluorocarbons, find their way up into the stratosphere where, through a complex series of chemical reactions, they destroy some of the ozone. As a result of this discovery, an international treaty was signed in 1973 called the Montreal Protocol, and the manufacture of these chemicals was greatly reduced.
The ozone layer has since begun to recover somewhat as a result of these efforts, but there is some science which now suggests that the major volcanic eruptions (mainly El Chi chon in 1983 and Mt. Pinatubo in 1991) which have occurred since we started monitoring ozone with satellites in the late 1970's, could have also contributed to the ozone depletion.
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