Ozone hole, Ozone depletion

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Name- ANKIT SARKAR
Roll Number- 16501313003
Department of Civil Engineering
C.I.E.M
Under the guidance of Prof. Mrinal K Ghose

2. Ozone is a form of oxygen (O3), Most of the atmospheric
ozone occurs in the stratosphere region, the greatest
concentration of ozone occurs between 19-30km. This band
of ozone rich air is called ‘Ozone-Layer’.
Ozone is both beneficial and harmful to us but the depletion
of ozone layer is very much harmful to the environment
and habitats.
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3. LAYERS OF THE ATMOSPHERE
The atmosphere is divided into six layers. It is thickest near
the surface and thins out with height until it eventually
merges with space.
 1) The troposphere is the first layer above the surface and
contains half of the Earth's atmosphere. Weather occurs
in this layer.
 2) Many jet aircrafts fly in the stratosphere because it is
very stable. Also, the ozone layer absorbs harmful rays
from the Sun.
 3) Meteors or rock fragments burn up in the mesosphere.
 4) The thermosphere is a layer with auroras. It is also
where the space shuttle orbits.
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4.  5) The atmosphere merges into space in
the extremely thin exosphere. This is
the upper limit of our atmosphere.
 6) The ionosphere overlaps the other
atmospheric layers. The air is ionized
by the Sun’s UV light. These ionized
layers affect the transmittance of radio
waves.
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Ozone
layer

5. THE SUN’S ULTRAVIOLET
RAYSThe sun emits energy over a broad spectrum of
wavelengths:
 visible light that we see
 infrared radiation that you feel as heat
 ultraviolet (UV) radiation that we can’t see or
feel.
 UV radiation has a shorter wavelength and
higher energy than visible light.
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6. ADVANTAGES & DISADVANTAGES OF UV
RAYS:-
 Fortunately for life on Earth, our atmosphere’s
stratospheric ozone layer shields us from most UV
radiation.
 It affects human health both positively and negatively.
 Short exposure to UVB radiation generates vitamin D,
Sterilization, Pest Control, Authentication of documents.
 High exposure of UVB radiation can causes skin diseases,
even skin cancer.
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7. THE OZONE LAYER
 The ozone layer is a deep layer in the
stratosphere, encircling the Earth,
that has large amounts of ozone in it.
 The layer shields the entire Earth
from much of the harmful ultraviolet
radiation that comes from the sun.
 For nearly a billion years, ozone
molecules in the atmosphere have
protected life on Earth from the
effects of ultraviolet rays.
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9. THE OZONE HOLE AND ITS CAUSES
 Recently, chlorofluorocarbons (CFCs) were used
a lot in industry and elsewhere to keep things
cold and to make foam and soaps.
 Strong winds carry CFCs up into the
stratosphere where UV radiation breaks them
apart, releasing chlorine atoms.
 Each chlorine atom can attack and break apart
(destroy) as many as 100,000 ozone molecules
during the time it is in the stratosphere.
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10.  The chlorine from CFCs reduces (depletes) the amount
of ozone in the stratosphere.
 Other ozone-eating chemicals are pesticides such as
methyl bromide, halons used in fire extinguishers, and
methyl chloroform used in businesses.
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11. Damage to the ozone layer can cause the
following:
 Skin cancer
 Cataracts
 Suppression of the immune system
 Premature aging of the skin
 Since the benefits of sunlight cannot be separated
from its damaging effects, it is important to
understand the risks of overexposure, and take
simple precautions to protect yourself.
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10% depletion in ozone results in 30% increase of skin cancer

12. OBSERVATIONS ON OZONE
LAYER DEPLETION
There are many observations on the
ozone layer. The following are a few
observations:
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13. OBSERVATION 1
 Scientists did predict that ozone depletion should
peak around year 2010.
 As world-wide controls reduce the release of CFCs
and other ozone-eating substances, nature will repair
the ozone layer.
 By year 2065 stratospheric ozone should return to
the amount present in 1980.
 Until then, we can expect higher levels of UV
radiation at the Earth's surface.
 We need to take care to avoid the bad health effects
that could result from too much UV radiation.
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15. OBSERVATION 2
 Most countries have seen the threats created by ozone
depletion and agreed to a treaty called the Montreal
Protocol.
 This Protocol will help humans to stop making and
using ozone-eating chemicals.
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16. MISCONCEPTIONS ABOUT THE OZONE
LAYER DEPLETION
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COMMON MISTAKE FACT
Global warming is caused by
the ozone hole which was
created by chemicals like CFC
etc.
The ozone layer protects the
Earth from the Sun’s harmful
UV rays. Hole in the ozone
layer has been caused by
chemicals released by humans.
CFC’s are “too heavy” to
reach the stratosphere.
CFC’s are commonly believed
to be heavy. But atmosphere
gases are not sorted by weight.
The wind mixes the gases and
they reach the atmosphere.

17. PROTECTING THE OZONE LAYER
 The ozone layer must be protected.
 For this the use of CFC’s has to be stopped.
 We must buy products that are labeled “ozone
friendly” or “ CFC free”.
 Substitutes for CFC’s should be used.
 HCFC’s are substitutes for CFC’s.
 Let us all take a step ahead and save the ozone layer.
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CONCLUSION
Ozone is both beneficial and harmful to us. Ozone Depletion
can cause a variety of health problems in humans.
So its our duty to protect the ozone layer. Some
international conventions like Vienna Convention and
Montreal Protocol are of greatest success stories.
The Climate of Antarctica has changed a lot for
Ozone depletion, future will reflect both ozone recovery and
GHG warming.

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REFERENCES
 http://en.wikipedia.org/wiki/Ozone_depletion
 http://www.epa.gov/sunwise/doc/uvradiation.html
http://www.unep.org/
 http://ozone.unep.org/en/treaties-and-decisions/montreal-
protocol-substances-deplete-ozone-layer
 TIDEE Journal- Depletion of Ozone Layer by Mrinal K Ghose

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