The ozone layer is a thin part of the stratosphere that protects the Earth from harmful UV radiation from the sun. It contains high concentrations of ozone which absorbs most UV radiation. Ozone depletion is caused by ozone-depleting substances like CFCs releasing chlorine and bromine atoms that destroy ozone. This allows more UV radiation to reach the Earth's surface and increases risks of skin cancer, eye cataracts, and harm to plants and animals. International agreements like the Montreal Protocol phased out most ozone-depleting substances, and models predict the ozone layer will recover by 2050-2075.

5. • 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

7. • The ozone layer refers to a region of
Earth's stratosphere that absorbs
most of the Sun's UV Radiation.
• It contains high concentrations of
Ozone(O3) relative to other parts of
the atmosphere.
• The ozone layer is mainly found in
the lower portion of the
Stratosphere.
• The ozone layer was discovered in
1913 by the French physicists Charles
Fabry & Henri Buisson.

8.  The sun emits energy over a broad spectrum of
wavelengths:
 Visible light that you see
 Infrared radiation that you feel as heat
 Ultraviolet (UV) radiation that you can’t see or
feel.
 UV radiation has a shorter wavelength and higher
energy than visible light.

10.  Ozone depletion describes two
phenomena : a steady decline of
about 4% per decade in the total
volume of in 's
,the .
destruction of ozone is
by atomic . The main
source of these halogen atoms is
refrigerants, solvents,
propellants, and foam-blowing
agents ( ).
 CFCs and other contributory
substances are referred to as
ozone-depleting substances
(ODS).

12. • Seasons
• Weather conditions, and
• Solar cycles

14. Ozone-Depleting
Substance(s) (ODS)
 Chlorofluorocarbons (CFC 11, CFC 12, CFC 13)
 Methyl bromide (CH3Br)
 Halons (halon-1211, halon-1301, halon-2402)
 Carbon tetrachloride (CCI4)
 Hydrochlorofluorocarbons (HCFC 22 and HCFC 123)

15. CFCS AND OTHER RELATED
COMPOUNDS
Chlorofluorocarbons (CFCs) and other
halogenated ozone depleting
substances (ODS) are mainly
responsible for man-made chemical
ozone depletion. The total amount of
effective halogens (chlorine and
bromine) in the stratosphere can be
calculated and are known as the
equivalent effective stratospheric
chlorine(EESC)

16. CFCs & Ozone

17. And the effects of all those
CFCs...

18. October 1979 October 2007

19.  Since the 1970’s the ozone hole has been
increasing in size over the Antarctic.
 For the first time, in September of 2000, the ozone
hole became so large it actually left populated
areas of southern Chile fully exposed to the
effects of the Sun’s UV rays.

20. Effects of Ozone
Depletion

21.  The effect of ozone depletion is
the increased UV-B radiation
reaching Earth’s surface.
 Effects on Humans:
•Sunburn
•Sun-damaged skin
•Cataracts
•Snow blindness
•Skin cancer

22. • Reduced effectiveness of
immune system
• Respiratory illness and
heart problems

23. • As ozone levels in the stratosphere are
depleted, more solar radiation penetrates the
Earth’s atmosphere.
• This affect results in an increase in solar
radiation reaching the Earth’s surface adding
to an increase in surface temperature.
• In turn, global warming actually results in a
warming of the troposphere, but a cooling of
the stratosphere, hindering the ozone layer’s
natural chemistry for repairs.

25. Mitigations

26.  After the discovery of ozone depletion in the late 1970’s,
many countries agreed that something must be done
worldwide to stop the production of man-made, ozone
harmful products.
 The international community adopted the Vienna
Convention in 1985 followed by the Montreal Protocol in 1987.
 The latest reports confirm that it has led to the phasing out of
about 95% of the consumption of ozone-depleting
substances (ODS) listed in the agreement. In turn, this has led
to the prospect of the ozone layer recovering by 2050 to
2075.
 Furthermore, the phasing out of ozone-depleting substances
has helped to fight climate change since many of these
chemicals are also powerful greenhouse gases. According to
a recent study, the phasing out of substances under the
Protocol led to more reductions in greenhouse gases than
what is foreseen under the Kyoto Protocol.
So what are we doing about it?

27. Image
Segmentation

28. Presenters….