Why it is in news?

• An international ban on chlorine-containing man-made chemicals called chlorofluorocarbons (CFCs), has resulted in about 20% less ozone depletion.

CFCs and OZONE:

•  CFCs are long-lived chemical compounds that eventually rise into the stratosphere, where they are broken apart by the sun’s ultraviolet radiation, releasing chlorine atoms that go on to destroy ozone molecules.
• CFCs have lifetimes from 50 to 100 years, so they linger in the atmosphere for a very long time.
• Stratospheric ozone protects life on the planet by absorbing potentially harmful ultraviolet radiation that can cause skin cancer and cataracts, suppress immune systems and damage plant life.
• The Antarctic ozone hole forms during September in the southern hemisphere’s winter as the returning sun’s rays catalyze ozone destruction cycles involving chlorine and bromine that come primarily from CFCs.
• When ozone destruction is ongoing, chlorine is found in many molecular forms, most of which are not measured. But after chlorine has destroyed nearly all the available ozone, it reacts instead with methane to form hydrochloric acid
• According to the study published in the journal Geophysical Research Letters, the Antarctic ozone hole should continue to recover gradually as CFCs leave the atmosphere, but complete recovery will take decades.

THE HINDU