2. 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.
THE SUN’S ULTRAVIOLET RAYS
2
3. It affects human health both positively and negatively.
Short exposure to UVB radiation generates vitamin D,
but can also lead to sunburn depending on an
individual’s skin type.
Fortunately for life on Earth, our atmosphere’s
stratospheric ozone layer shields us from most UV
radiation
3
4. OZONE LAYER
The ozone 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.
5. 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
6. 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.
7. 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---
8. 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
9. 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.
10. 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.
11. 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.
12. 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).
13. 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.
14. 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.
15. 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 .
