Creator has bestowed the mankind with end number of blessings out of those, one of the biggest blessing is planet earth. Perhaps ,earth is the only planet where life is possible as of now. Earth is also known as green planet or blue planet. But out of greed and the unprecedent growth of technology and modernization man has been destroying this blessing ruthlessly and one of the deadly consequence that followed this ruthlessness is ozone depletion.

Earths atmosphere consists of different layers based on the temperature and the gaseous matter they contain. In Stratosphere i.e. earth's second layer that starts above 15 and goes up to approximately 35 km's high contains most of the ozone and this region containing ozone in abundance is known as ozone layer .ozone layer is a protective layer or a shield or an umbrella that protects us from the harmful radiations of the sun .ozone layer works as a barrier to the ultraviolet radiations to reach to the surface of earth.

These radiations if reached to surface of earth will have threatening effect up on life on earth .ozone Is of two types -good ozone and bad ozone .Good ozone is one present in stratosphere that protects earth from ultraviolet rays where as bad ozone is present in troposphere and is harmful for breathing and causes many problems to plants and animals, it also causes the urban smoke. Ozone depletion is one of the major problem before present generation.

Ozone Depletion:

The destruction of the ozone molecules in the ozone layer due to different factors is known as ozone depletion .in 1970s,scientists realized a threat to ozone layer by the accumulation of different gases in atmosphere. This diminution of ozone molecules in this region was anticipated to have a cautionary impact upon life on the earth as due to the reduction of ozone molecules in ozone layer ,the chances for the harmful ultraviolet radiations would be high to reach on the surface of earth.

Now ,the main question that arises here is that how this ozone is being depleted ,what are the factors responsible for its depletion. The ozone in the stratosphere is being produced and destroyed all the time through natural processes like the sun emits ultraviolet C radiations and when it reaches the stratosphere its completely absorbed by oxygen molecule ,UV-C splits oxygen molecules into oxygen atoms and these oxygen atoms react with oxygen molecule to produce ozone. Also other gases like hydrogen and nitrogen present in stratosphere participate in reaction processes and decreases amount of ozone by destroying it to oxygen.

Moreover volcanos and stratospheric winds, sunspots are also responsible for ozone depletion. However, these natural phenomenon of ozone production and depletion are not left undisturbed by humans leading to the disturbance of consistent ozone concentration in stratosphere. The human interference is by way of creating the substances that destroy ozone molecules and these substances are referred to as ozone depleting substances or OD'S.

Ozone Depleting Substances:

The substances that deplete the ozone layer by destroying the ozone molecules in it are known as ozone depleting substances. These are the chemicals that react with ozone molecules and destroy it. Manmade chemicals containing halogens were determined to be main cause of ozone loss .chlorine and bromine atoms in atmosphere come in contact with ozone and destroy ozone molecules .it is estimated that one chlorine can destroy 100,000 molecules of ozone. These products were used in non stop use in everyday life of humans all around the world as refrigerants ,foam blowing agents ,industrial solvents, aerosol spray propellants ,fumigants.

Some of the main ozone depleting substances are : chlorofluorocarbons (commonly known as CFC'S) ,Hydrochlorofluorocarbons (HFC'S),Halons, Methyl bromide .OD,s are split into two groups under Clean Air Act 1970: class I OD'S such as CFC'S and class II OD'S such as HFC'S. The use of these substances have been controlled by different international conventions on environmental protection such as The Montreal protocol 1987,which is a global agreement to make phase out of ozone depleting substances.

Effects Of Ozone Depletion:

The depletion of the protective ozone layer has devastating effect upon life on earth. Once the harmful ultraviolet radiations from sun reach to the surface of earth ,life on earth will be destroyed and the first target would be humans. Apart from the humans plants, marine life etc would also get impacted. Some of the main effects of ozone depletion are:

• Effect on humans: Early signs of ageing, skin cancers, eye cataract, weakened immune system, genetic mutations, etc.
• Effect on animals: Cancers, impaired larval development, decreased reproductive capacity, etc.
• Effect on environment: Less productivity, interrupted photosynthetic processes, reduced survival of plants, etc.
• Effect on marine life: Damage to phytoplankton, disturbed food chain, etc.

Ozone Hole:

In 1980's scientists discovered a hole in ozone layer above Antarctica. Ozone hole is not a hole in its literal sense, its basically a thinning of ozone layer having less concentration of ozone molecules .The discovery of Antarctic ozone hole was first announced in a paper by British Antarctic survey's joe Farman, Brain Gardiner and Jonathan Shanklin. Ozone hole is the region over Antarctica with total ozone of 220 Dobson units or lower. This thinning of ozone layer was anticipated to have devastating effect on earth and the nations come forward and signed a protocol, The Montreal protocol 1987 to make the phase out of ozone depleting substances to protect these anticipated consequences of ozone depletion.

Prevention Of Ozone Layer: International Trends

When the problem of ozone depletion and ozone hole over Antarctica came before the world, the global community come forward to resolve the issue and in response to the problem spotted, The Vienna Convention 1985 was signed, This convention gave the principles and sought the support of countries to prevent the ozone depletion. It was the first convention to be signed by every country involved and it got universal ratification till 2009,however it is still making progress.

After Vienna convention, The Montreal Protocol 1987 was signed , it was a global agreement aimed at phase out of ozone depleting substances. Although this protocol was designed to phase out the production and consumption of ozone depleting substance, but in replacement of these substances hydrofluorocarbons were used but they have proven to be powerful green house gases. In this regard, after several years parties on 15 October 2016 agreed to amend protocol to include control measures to reduce hydrofluorocarbons and this amendment came to be known as The Kigali Agreement and through this amendment successful phasedown is expected to avoid up to 0.5 degree Celsius of glob temperature rise by 2100.

All these conventions have contributed to a great extent to protect ozone layer by creating global policy framework for protecting ozone layer and climate.

National Trends:
Apart from the international trends, efforts at national level have also been made, India became a party to Montreal protocol in 1991 and in obligation to this protocol India in 2000 passed ozone depleting substances(Regulation) rules to make phase out of ozone depleting substances .These were subsequently amended in 2001,2003,2004,2005,2014 and very recently in 2019.These rules were made under Environmental Protection Act. These regulate the import, use, production, trade, export of ozone depleting substances. Amendment of 2019 also included regulatory mechanism issuance of licenses by banning the issuance of import licenses for HCFC-141b from January, 1 2020.

References:

• Nasa Ozone Watch.
• epa.gov.
• Ozone.unep.org, ozone secretariat

Written By: Masrat Riyaz, B.A Llb 6th Semester, Central University Of Kashmir.