Suhasini Gupta
16th September is celebrated as “World Ozone Day”. This day has been celebrated since 1994 and has been established by United Nations General Assembly. This day is intended to spread awareness among people regarding the depletion of ozone layer. Ozone is an inorganic molecule containing three atoms of oxygen (O3).Ozone acts as a shield by preventing harmful ultraviolet radiations to enter the earth’s surface. UV radiation could injure or kill life on Earth. Ozonosphere is the region in stratosphere that contains concentration of ozone sufficient to block most of the ultraviolet radiations coming from sun. The ozonosphere is found 15-35 km above the surface of the earth. Ozone is created when the kind of oxygen we breathe-O2-is split apart by sunlight into single oxygen atoms. Single oxygen atoms can re-join to make O2, or they can join with O2 molecules to make ozone (O3). Ozone is destroyed when it reacts with molecules containing nitrogen, hydrogen, chlorine, or bromine.
Ozone is getting depleted by various substances like Chlorofluorocarbons (CFCs), Halon, Carbon tetrachloride (CCl4), Methyl chloroform (CH3CCl3), Hydrobromofluorocarbons (HBFCs) etc. These substances are called ozone depleting substances (ODSs). These substances are widely used in refrigerators, air conditioners, fire extinguishers, in dry cleaning etc. ODS are very stable, nontoxic and environmentally safe in the lower atmosphere, which is why they became so popular in the first place. However, their very stability allows them to float up, intact, to the stratosphere. Once there, they are broken apart by the intense ultraviolet light, releasing chlorine and bromine. Chlorine and bromine demolish ozone at an alarming rate, by stripping an atom from the ozone molecule.
Ozone depletion is one of the major problems faced by our planet earth. Moreover, ozone depletion is one of the most important reason responsible for Global Warming. Depletion of ozone layer allows entering of UV rays from sun into the earth’s atmosphere which is associated with a number of health related and environmental issues. The major impacts of ozone depletion on human beings are skin cancer, ageing of skin, damage to immune system, eye damage like cataract problems, chest pain, throat irritation. These UV rays adversely affect other life forms also. In case of marine ecosystem, it adversely affects planktons which play an essential role in food chain and oceanic carbon cycle. UV rays affect plants also. It can also directly affect the plant growth by altering the physiological and developmental processes of the plants.
Ozone layer depletion leads to decrease in ozone in the stratosphere and increase in ozone present in the lower atmosphere. Presence of ozone in the lower atmosphere is considered as a pollutant and a greenhouse gas. The depletion of ozone layer has trickle down effects in the form of global warming, which in turn leads to melting of polar ice, which will lead to rising sea levels and climatic changes around the world. It has been found by U.S Environment Protection Agency that one atom of chlorine can destroy more than a hundred thousand ozone molecules. e are two regions in which the ozone layer has depleted :- In the mid-latitude over Australia, ozone layer is thinned. This has led to an increase in the UV radiation reaching the earth. It is estimated that about 5-9% thickness of the ozone layer has decreased, increasing the risk of humans to over-exposure to UV radiation owing to outdoor lifestyle. Moreover, in atmospheric regions over Antarctica, ozone layer is significantly thinned, especially in spring season. This has led to the formation of what is called ‘ozone hole’. The ozone hole is not technically a “hole” where no ozone is present, but is actually a region of exceptionally depleted ozone in the stratosphere over the Antarctica that happens at the beginning of Southern Hemisphere spring . Ozone holes refer to the regions of severely reduced ozone layers. One of the largest such hole appears annually over Antarctica between September and November.
It has been found by a study that about 90 % of CFCs currently in the atmosphere were emitted by industrialized countries in the Northern Hemisphere, including the United States and Europe. These countries banned CFCs by 1996, and the amount of chlorine in the atmosphere is falling now. But scientists estimate that it will take another 50 years for chlorine levels to return to their natural levels.
World ozone day is celebrated on 16th September to mark the day back in 1987 when Montreal Protocol was signed. The Montreal Protocol on Substances that Deplete the Ozone Layer is an international treaty designed to protect the ozone layer. The treaty was originally signed in 1987 and substantially amended in 1990 and 1992. The Montreal Protocol stipulates that the production and consumption of compounds that deplete ozone in the stratosphere–chlorofluorocarbons (CFCs), halons, carbon tetrachloride, and methyl chloroform are to be phased out by 2000 (2005 for methyl chloroform). The Montreal Protocol is widely considered as the most successful environment protection agreement.
World Ozone Day is celebrated all over the world. On this day, educational institutions organize special events and activities that focus on ozone the ozone layer, climate change and ozone depletion. Other activities that are organized by different community groups, individuals, schools and local organizations across the world include: the promotion of ozone-friendly products; special programs and events on saving the ozone layer, the distribution of the UNEP’s public awareness posters to be used for events centered on the International Day for the Preservation of the Ozone Layer and the distribution of awards to those who worked hard to protect the Earth’s ozone layer. Buying and using recycled products, saving of energy, using of public transport can do a lot in combating ozone layer depletion. The most important thing that we can do is spreading awareness. Our individual efforts will go a long way in saving the earth’s blanket and keep our planet earth livable for us and our future generations.
(The author is a Student of M.Sc. Economics in Shri Mata Vaishno Devi University, Katra)
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