ozone depletion

1. KARNATAKA VETERINARY ANIMAL
AND FISHERIES SCIENCES UNIVERSITY
BIDAR
VETERINARY COLLEGE HEBBAL

2. OZONE LAYER DEPLETION

3. CONTENT OF PRESENTATION
 What it is ?
 Where it is?
 Why is it important to life on earth?
 Why it is depleting?
 What are effects of the ozone layer depletion?
 How can we save it?

4. WHAT IS THE OZONE ?
 Ozone (o3) molecules consist of three oxygen atoms that forms when free Oxygen molecules
bond to O2 molecules .
 This gas is extremely rare in atmosphere, representing just out of every 10 million molecules. In
spite of this small amount ozone plays a vital role in the atmosphere.
 Ozone is highly corrosive and toxic and is used as a disinfectant .
 Ozone gas can be created or destroyed by the sun’s ultraviolet rays.

5. Where is ozone found in the atmosphere?
 Ozone is mainly found in two regions of the Earth’s atmosphere. Most ozone(about
90%)resides in a layer that begins between 6 and 10 miles(10 to 17kilometers) above the
Earth’s surface and extends upto about 30miles (50kilometers).this region of atmosphere
is called stratosphere. The ozone in this region is commonly known as the ozone layer

7. Why is it important to life on earth?
 Ozone present in the stratosphere plays a beneficial role by absorbing most of the biologically
damaging ultraviolet sunlight .The absorption of ultraviolet radiation by ozone creates a source
of heat .Ozone thus plays a key role in the temperature structure of the earth’s atmosphere.
 Without the filtering action of the ozone layer, more of the sun’s UV radiation would penetrate
the atmosphere reach the earth’s surface.
 Many experimental studies of plants and animal and clinical studies of humans have shown the
harmful effects of excessive exposure to UV radiation.
 UV rays penetrate the Earth’s atmosphere at 3 different wavelengths called UV-A,UV-B and
UV-C rays .ozone will eliminates most of UV-C.

8. OZONE HOLE

9. What is the ozone hole?
 The ozone hole is an annual thinning of the ozone layer over Antarctica .The most pronounced
decrease in ozone has been in the lower stratosphere .However the ozone hole is most usually
measured not in terms of ozone concentrations at these levels(which are typically of few parts
per million) but by reduction in total column ozone.

11. What causes ozone layer depletion?
Ozone Depleting Substances:
 Substances that causes the depletion of the ozone layer are called ozone depletion
substances (ODS).the different ODS are
 CFC’s
 Halons- used in fire extinguishers
 Carbon Tetrachloride's
 Methyl Chloroform
 Hydro fluorocarbons(HCFC’s)
They are found in refrigerators, cleaning agents, sprays, pesticides ,air conditioners, car
emissions.

12.  1). Chlorofluorocarbons: this id the cause for the nearly 80% of the ozone depletion. It is found in
many industrial solvents and the hospital sterilants. Besides even the foam products that are used in
foaming mattresses etc for foam padding contain CFC’s.
 2). Carbon tetrachloride: this is widely used in fire extinguishers.
 3). Halones: it is found that ozone suffers more damage from halons than an equal amount of
chlorofluorocarbons.
 4). Hydro fluorocarbons: they are the green house gases that can harm the ozone layer.
 5).Methyl Chloroform: some of the adhesives and chemical solvent contain methyl chloroform
which is yet again, another cause for deleting ozone layer.

13. CONTD..

14. Ozone Depletion Process
 UV radiation breaks off a chlorine atom from CFC molecule.
 The chlorine atom attacks an ozone molecule, breaking it apart and destroying the ozone .
 The result is an ordinary oxygen molecule and a chlorine monoxide molecule(CIO).
 The chlorine monoxide molecule is attacked by a free oxygen atom releasing the chlorine
atom and forming an ordinary oxygen molecule.
 The chlorine atom is now free to attack and destroy another ozone molecule.one chlorine
atom can repeat this destructive cycle thousands of times. One chlorine atom from CFC can
destroy up to 100,000 ozone atoms in catalytic process.

16. What are Effects of the Ozone Layer Depletion?
 The two most important effects of the ozone layer depletion are:
 Green house effect
 Global warming

17. The Greenhouse Effect
 The greenhouse effect is the process in which greenhouse gases absorbs radiation(the infrared
rays) and re- radiates it in all directions.
 Since part of this re- radiation is back towards the surface and lower atmosphere, it results in an
elevation of the average surface temperature above what it would be in the absence of the gases.

18. CONTD..

19. Global Warming
 Global warming refers to an un equivocal and continuing rise in the average temperature of
Earth’s climate system .
 Most of global warming is being caused by increasing concentration of greenhouse gases
produced by human activities.
 Future climate change and associated impacts caused by global warming will vary from region to
region around the globe.
 Effects of global warming are increase in spread of diseases, melting of ice caps, floods, cold
waves.

20. CONTD..

21. Other Effects of Ozone Layer Depletion
 Skin cancer-Exposure to UV rays will lead to increased risk for developing of several types of skin
cancers like Malignant Melanoma, basal and squamous cell carcinoma .
 Eye cancer- Direct exposure to UV rays will lead to problems like Cataract, snow blindness.
 Damage to immune system.
 Aging of skin.
 UV rays affect different amphibians by hampering the growth and development in larvae stages
and even cause retinal damage and blindness.

22. CONTD..

23. How to Save Ozone ?
 Montreal Protocol
 After discovery of ozone depletion in late 1970’s many countries agreed to stop production and
usage of man made ozone harmful products.
 The international adopted the Vienna Convention in 1985 followed by Montreal protocol
 Governments recognized the need for stronger measures to reduce the production and
consumption of CFC’s.
 The latest reports confirm that it has led to phasing out about 95% of consumption of ODS listed in
agreement , in turn this, lead to prospect of ozone layer recovering by 2050 to 2075.

24. How can we contribute?
HOUSE HOLD PRODUCTS
 Buy the house hold products which don’t contain CFC’s.
 Buy the AC and Refrigerators that don’t have HCFC’s as refrigerant.
 Buy aerosols product that don't have HCFC’s and CFC’s as propellants.
 Conduct regular inspection and maintenance of AC and Refrigerators appliances to prevent and minimize
refrigerant leakage.
 Safe disposal of old appliances prevents CFC’s and HCFC’s from being released into the environment.
 “BE THE CHANGE YOU WANT TO SEE IN OTHER’S”
 Children education.
 Awakening Adults .
 Plant more trees and Save the existing plantation.