The ozone layer is a layer in the stratosphere between 20-30 km above the Earth's surface that contains 90% of the atmosphere's ozone. Ozone is formed through the Chapman cycle where oxygen is converted to ozone via ultraviolet radiation. Ozone depletion occurs when gases like CFCs and halons react with ozone due to UV radiation, forming chlorine atoms that can destroy 100,000 ozone molecules each. This causes thinning of the ozone layer, known as the ozone hole over Antarctica. Ozone depletion leads to increased UV radiation reaching the Earth, harming humans, animals, plants and contributing to global warming. International agreements like the Montreal Protocol aim to phase out ozone depleting

5. EFFECTIVE FILTER
 200 – 315 nm – UV radiations in wavelength

6. OZONE LAYER
The ozone layer is a layer is a layer in the
earth’s atmosphere which contains 90% of
atmospheric ozone (O3). The ozone layer is found
in the lower portion of the stratosphere from
about 20 to 30 km above earth’s surface. It’s
thickness varies seasonly and geographically.

8. FORMATION OF OZONE
LAYER
The ozone layer or the ozone forms by
conversion of atmospheric oxygen(O2) into ozone
(O3), this process is called as Chapman cycle .
The oxygen get photolyzed by U.V.rays to
form oxygen radical.
U.V. Light
O2
2
O

9. The oxygen radical then react with
molecular oxygen and forms ozone molecule
(O3).
At the same time ozone gets reduce to oxygen
by reacting with oxygen radical.
O3
O2
2
O
O3
O2O
So, ozone is constantly get created and destroyed by
Chapman cycle, which is a natural process.

10. DOBSON UNIT
 A unit of measurement for the total amount of
ozone in the atmosphere above a point on the
earth's surface,
 One Dobson unit being equivalent to a layer of pure
ozone 0.01 mm thick at standard temperature and
pressure.

11.  The Dobson unit is named after Gordon Dobson,
who was a researcher at the University of Oxford.
In the 1920s, he built the first instrument to
measure total ozone from the ground, now called
the Dobson ozone spectrophotometer

14. OZONE DEPLETION
Decrease in concentration of ozone and
thinning of ozone layer is called Ozone depletion.
From industries and our day to day life many
gases like Chlorofluorocarbons (CFC’s) , Hydro-
chlorofluorocarbons (HCFC’s) , halons, halogens,
etc. get evolved in atmosphere which are mainly
responsible for ozone depletion, as it contains or
produce Chlorine (Cl) atom.
let’s take look at the process of ozone depletion---

15. PROCESS OF OZONE
DEPLETION
Due to solar radiation i.e. U.V. Rays CFC’s , HCFC’s
breaks and form Cl atom which react with ozone molecule and
forms Chlorine monoxide (ClO). Chlorine monoxide then
reacts with oxygen radical to form Chlorine atom and molecular
oxygen.
O3
U.V. Light
O2
O O2

16. NET REACTION :
O3
O2
2
U.V. Light
O
As Cl atom acts as a catalyst , one single Cl
atom can destroy much amount of ozone molecules.

17.  Each chlorine radical can destroy 1,00,000
molecules of ozone

18. OZONE HOLE
As a result of ozone depletion, over
Antarctica the ozone hole is formed. This ozone
hole leads to melting of ice of Antarctica, increase
in sea level and other harmful effects on it’s
environment.

19. OZONE DEPLETING SUBSTANCES
Ozone depleting substances are
mainly CFC’s, HCFC’s, Halons, etc.
which are found in Refrigerators,
Cleaning agents, sprays, Pesticides, Air
conditioners, car emissions, etc.

20. EFFECT OF OZONE DEPLETION
Due to ozone depletion harmful U. V. Rays such
as UV-B Radiation reaches to earth which leads to
harmful effects on animals, plants, aquatic life as well
as on humans also.
Effect on Aquatic System: Affects phytoplankton,
fish, larval crabs. Decrease in amount of phytoplankton
increase the CO2 in atmosphere which contribute the
global warming.
Effect on Materials: Degradation of paints and
plastics.
Effect on Climate: Global Warming (Increasing
the Average temperature of the Earth’s surface).

21. Effect on Human Health:
Damage genetic materials in the cells.
Leads to more people suffering from Cataracts.
Causes cancer, allergies and some other
infectious disease.
10% depletion in ozone layer results in
30% increase in skin cancer infection.

22. PREVENTIONS
Limit private vehicle driving to decrease vehicle
emissions.
By using Eco-friendly household or other cleaning
agents.
Avoid excess use of pesticides. Replacing CFC’s by
other material which are less damaging.
Manufacturing and using of ozone depleting
chemicals must be stopped, etc.

23. But, for controlling ozone
depletion the most important thing
is to aware people about it,
and that’s why International
Environmental Community declared
16 September as a World Ozone
Day .

24. The Montreal Protocol on Substances that Deplete the
Ozone Layer (a protocol to the Vienna Convention for the
Protection of the Ozone Layer) is an international treaty
designed to protect the ozone layer by phasing out the
production of numerous substances that are responsible for
ozone depletion.