Ozone is a highly reactive and unstable gas, which is formed by the recombination of oxygen (O2) atoms in the presence of intense radiation. Its symbol is O3.
The ozone layer is a naturally occurring zone found in the stratosphere, situated between 10-15 kms above the surface of the Earth. The main function of the ozone layer is to act as a shield against ultraviolet (UV) radiations from the Sun because these rays are harmful to life.
Destruction of the stratospheric ozone layer which shields the earth from ultraviolet radiation harmful to life. …
Causes Of Ozone Layer Depletion:
The Main Ozone-Depleting Substances (ODS)
The most widely used ODS, accounting for over 80% of total stratospheric ozone depletion.
Used as coolants in refrigerators, freezers and air conditioners in buildings and cars manufactured before 1995.
Found in industrial solvents, dry-cleaning agents and hospital sterilants.
Also used in foam products — such as soft-foam padding (e.g. cushions and mattresses) and rigid foam (e.g. home insulation).
Used in some fire extinguishers, in cases where materials and equipment would be destroyed by water or other fire extinguisher chemicals. In B.C., halons cause greater damage to the ozone layer than do CFCs from automobile air conditioners.
Used mainly in industry — for vapour degreasing, some aerosols, cold cleaning, adhesives and chemical processing.
Used in solvents and some fire extinguishers.
Hydro fluorocarbons (HCFCs)
HCFCs have become major, “transitional” substitutes for CFCs. They are much less harmful to stratospheric ozone than CFCs are. But HCFCs they still cause some ozone destruction and are potent greenhouse gases.
The cause of ozone depletion is the increase in the level of free radicals such as hydroxyl radicals, nitric oxide radicals and atomic chlorine and bromine. The most important compound, which accounts for almost 80% of the total depletion of ozone in the stratosphere are chlorofluorocarbons (CFC). These compounds are very stable in the lower atmosphere of the Earth, but in the stratosphere, they break down to release a free chlorine atom due to ultraviolet radiation. A free chlorine atom reacts with an ozone molecule (O3) and forms chlorine monoxide (ClO) and a molecule of oxygen. Now chlorine monoxide reacts with an ozone molecule to form a chlorine atom and two molecules of oxygen. The free chlorine molecule again reacts with ozone to form chlorine monoxide. The process continues and the result is the reduction or depletion of ozone in the stratosphere.
Effects Of Ozone Depletion
Following are the major effects of ozone layer depletion.
i) It will increase the risk of skin cancer
ii) It has resulted in melanomas, a kind of tumour.
iii) It greatly affects eyes and produces disease of vision.
iv) It suppresses immunity system of human beings.
v) UV rays damage various crops.
vi) It kills plankton and fish larvae.
vii) It causes sunburn in human beings.
viii) It causes spotting of leaves in plants and trees, thus decreases productivity of the plants.
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