It contains relatively high concentrations of ozone. This layer absorbs 97- 99% of the sun’s high frequency ultraviolet light, which is potentially damaging to life on Earth. However, ozone is a form of oxygen that can be destroyed easily by certain man- made chemicals.
In 1987, the leading industrial countries agreed to phase out these chemicals. Even so, satellites have shown that thinning of the ozone layer has continued over Antarctica. The ozone hole reached a record size – nearly 30 million sq. km – in 2000.
Smaller ozone holes have also appeared over the Arctic. These holes allow more UV light to reach densely populated areas of Europe.
Ozone hole as seen by Envisat ESA satellites such as ERS- 2 and Envisat play a key role in ozone hole studies. They enable scientists to monitor the size of the hole and learn more about what causes it to grow or shrink.
Envisat carries three instruments that can study ozone and the pollutants that attack it in the upper atmosphere. A more advanced ozone-monitoring installment will be launched on Europe’s Met Op spacecraft in 2005.
Depletion of the ozone layer allows more of the UV radiation, and particularly the more harmful wavelengths, to reach the surface, causing increased genetic damage to living creatures and organisms.
The ozone layer can be depleted by free radical catalysts, including nitric oxide (NO), hydroxyl (OH), atomic chlorine (CI), and atomic bromine (Br). Countries all over the world are studying and taking appropriate measures to prevent the loss of ozone layer.