Ozone Layer

Why in News?

• Recently, earth’s protective ozone layer is slowly but noticeably healing at a pace that would fully mend the hole over Antarctica in about 43 years

Highlights 

• While this is an achievement, the scientists warned of the detrimental effects of geoengineering technologies such as stratospheric aerosol injection on the ozone layer.
• Aerosol sprays, like other commonly used substances such as dry-cleaning solvents, refrigerants and fumigants, contain Ozone-Depleting Substances (ODS) including chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), halons, methyl bromide, carbon tetrachloride, and methyl chloroform.
• For the first time, the Scientific Assessment Panel examined the potential effects on ozone of the intentional addition of aerosols into the stratosphere, known as Stratospheric Aerosol Injection (SAI).
• SAI can increase sunlight reflection, thereby lowering the amount of heat that enters the troposphere. But this method “could also affect stratospheric temperatures, circulation and ozone production and destruction rates and transport”.
• Ozone is a special form of oxygen with the chemical formula O3. The oxygen we breathe and that is so vital to life on earth is O2.
• About 90% of ozone occurs naturally in the Earth’s upper atmosphere (Stratosphere) between 10 and 40 km above Earth’s surface, where it forms a protective layer that shields us from the sun’s harmful ultraviolet rays.
• This “good” ozone is gradually being destroyed by man-made chemicals referred to as ODS, including CFCs, HCFCs, halons, methyl bromide, carbon tetrachloride, and methyl chloroform.
• When chlorine and bromine atoms come into contact with ozone in the stratosphere, they destroy ozone molecules.
• One chlorine atom can destroy over 100,000 ozone molecules before it is removed from the stratosphere.
• Ozone can be destroyed more quickly than it is naturally created.
• Ozone layer depletion leads to an uptick in the incidence of skin cancer and cataracts in humans.