Ozone Layer and its Depletion - Causes and Effects

 

What is the ozone layer? To put it simply, the ozone layer is the earth’s personal shield. UV rays from the sun are our best natural source for Vitamin D. However, too much exposure to this radiation presents us with a myriad of problems like sunburns, premature aging in some cases, eye damage and have been linked with skin cancer. The ozone layer, which contains high concentrations of ozone (O3), protects us by absorbing most of this UV radiation from the sun. It is located as a thin layer in the earth’s stratosphere.
Ozone layer depletion refers to just that! The layer has been in a steady state of decline of around 4% since the past 50 years or so. In the Antarctic zone, the depletion levels are so high that there is a hole in the ozone layer.

Ozone layer depletion

Causes of Ozone Layer Depletion:

The main cause of ozone layer depletion is the build-up of CFCs (chlorofluorocarbons) in the atmosphere. When the CFCs reach the upper atmosphere, high UV radiation reacts with these and releases chlorine atoms. These free chlorine atoms react with ozone thereby leading to the depletion of the ozone layer. One chlorine atom can destroy millions of ozone atoms before it decomposes and this is why CFCs are extremely damaging to the ozone layer. The build-up of CFCs is caused by many applications like the production of refrigerants, anesthetics, aerosol sprays.

Substances that cause the depletion of the ozone layer are called Ozone Depleting Substances (ODS). The different ODS are
⦁ CFCs as we’ve already discussed
⦁ Halons – Used in fire extinguishers
⦁ Methyl Chloroform
⦁ Carbon Tetrachloride
⦁ Hydrofluorocarbons (HCFCs)

Funnily enough, ozone is like a double-edged sword. If there is a build-up of ozone layer close to earth’s surface, it is quite harmful to us. Why? It is corrosive in nature and pretty harmful if inhaled. Its perfect placement in the lower stratosphere doesn’t bring us into contact with it while still acting as a cover.

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Practise This Question

Which of the following is/are true?
I. Benzene hexachloride is a non-biodegradable pollutant.
II. Anthropogenic air pollutants are natural in origin.
III. Carbon monoxide is a primary air pollutant.
IV. Sulphur dioxide causes brown air effect during traffic congestion in cities.