The ozone layer was discovered in 1913 by the French physicists Charles
Fabry and Henri Buisson.
Ozone layer is a thin, fragile shield that contains relatively high
concentrations of ozone.
It shields the entire Earth from much of the harmful UV radiation that
comes from the sun
The atmosphere of the Earth is divided into 5 layers.
The layers are: troposphere, stratosphere, mesosphere, thermosphere
Ozone is a triatomic form of oxygen (O3) found in Earth’s upper and
Humans rely heavily on the absorption of ultraviolet B rays by the ozone
layer because UV-B radiation causes skin cancer and can lead to genetic
Layers of the Earth’s Atmosphere
Ozone is found in both the troposphere (lower atmosphere) and the stratosphere
Chemically forms when UV hits on stratosphere
Oxygen molecules dissociate into atomic oxygen
Atomic oxygen quickly combines with other oxygen molecules
to form ozone
O2 O + O
O + O2 O3
Ozone layer is being
destroyed by a group of
chemicals that are
called ODS or Ozone-
The main ODS are the following:
Chlorofluorocarbons (CFC 11, CFC
12, CFC 13)
Methyl bromide (CH3Br)
Halons (halon-1211, halon-1301,
Carbon tetrachloride (CCI4)
22 and HCFC 123)
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
Each chlorine atom can attack and break apart
(destroy) as many as 100,000 ozone molecules during
the time it is in the stratosphere.
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.
Hole in the ozone layer
October 1979 October 2007
Some Effects of Ozone Layer Depletion
Damages DNA which suppresses immune system
resulting in increase in infectious diseases e.g. , Skin
Cancer; Eye Cataracts
Plants & Trees
Reduces crop production, damage to seeds
Reduces quality of crops, damage to leaves.
Damage to plankton, aquatic plants, fish larvae,
Affects marine food chain
degrades paints, rubber, wood, & plastics,
especially in tropical regions
Ground Level Smog
Increase in the formation of Ground level ozone as a
High economic cost
Damages could be in billions of US dollars
An international agreement , signed by most of
the industrialized nations, to substantially
reduce the use of chlorofluorocarbons (CFCs).
The Montreal Protocol on Substances that
Deplete the Ozone Layer was designed to
reduce the production and consumption of
ozone depleting substances in order to reduce
their abundance in the atmosphere, and
thereby protect the earth’s fragile ozone Layer.
The protocol set limits on the production of
chlorofluorocarbons (CFCs), halons, and related
substances that release chlorine or bromine to
the ozone layer of the atmosphere.
THE MONTREAL PROTOCOL(1989)
Results to date
The Montreal Protocol is working.
There is clear evidence of a decrease
in the atmospheric burden of ozone-
depleting substances in the lower
atmosphere and in the stratosphere;
Some early signs of the expected
stratospheric ozone recovery are also
Furthermore, if the Parties were to
eliminate all emissions of ozone
depleting substances soon after 2006,
it would advance by about 15 years
(from around 2050 to 2035) the global
ozone layer recovery to pre-1980
Without the Montreal Protocol by 2050
Ozone depletion would have reached to at least 50 % in
the northern hemisphere’s mid latitudes
70% in the southern mid latitudes
Doubling on the UV-B radiation reaching earth’s surface
Estimated increases of
19 million more cases of non-melanoma cancer
1.5 million more cases of melanoma cancer
130 million more eye cataracts
There are many possible solutions to this problem, but it
wholly relies on us, humans.. The following are the soltuions
for decreasing the ozone hole in the atmosphere:-
Firstly the consumption all the cfcs should be
Companies should be held responsible for the disater they
are causing in the environment
And we should use the 3rs…. Which are reuse , recycle,
reduce initiative… so that the next generation doesnot
have to go through problems made by us.
And the use of cfcs should be ban.
ELEMENTS OF ENVIRONMENT (English) 6th Edition
(1995)by robert smith.
Ecosystem Principles and Sustainable Development
(1999) by swaminatham.
Books.google/ozone layer depletion