Ozone depletion O3 is explain in detail. Student of Superior Science College Peshawar Recently Studied B.S Zoology (4 Years)

1. Ozone
•O3
•a gas composed of three atoms of
oxygen
•Bluish gas that is harmful to breathe
•Nearly 90% of the Earth's ozone is in
the stratosphere and is referred to as
the ozone layer
•Ozone absorbs a band of ultraviolet
radiation called UVB

2. Ozone
• This layer absorbs 93-99% of the sun's high
frequency ultraviolet light.
• It is mainly located in the lower portion of
the stratosphere from approximately 10
km to 50 km above Earth Surface.
• The ozone layer was discovered in 1913 by
the French physicists Charles Fabry and
Henri Buisson.

3. Ozone-Depleting Substance(s) (ODS):
•Cfcs,
•Hydro cfcs,
•Halons,
•Methyl bromide,
•Carbon tetrachloride, and
•Methyl chloroform.

4. Various sources

5. Causing of Ozone Depletion
• Human activities such as releasing of various compounds like
Chlorine & Bromine can be a major cause of ozone damage.
• When the CFCs released into the atmosphere, the destruction
begins.
• The CFC molecules float towards the Stratosphere & contact with
UV rays causing Liberation of 1 chlorine atom.
• The Free chlorine reacts with Ozone (O3), forms Chlorine
Monoxide (CIO).
• CI + O3 O2 + CIO
• Then a Single oxygen atom reacts with a Chlorine monoxide
molecule, causing the formation of an oxygen molecule & single
chlorine atom.
• O + CIO CI + O2
• This Chlorine atom than continues the cycle & result in further
destruction

7. Ozone Depletion: CFCs Stays
1)CFCs remain stable in
Atmosphere due to
unreactivity.
2)Each CFC molecule lasts in
stratosphere for 65-100 years,
It Can convert 100,000 of O3 to
O2 during that time.

8. Measuring the Ozone Hole
• Between 1928 and 1958 Dobson established a
worldwide network of ozone monitoring stations
which continues to operate today. The "Dobson
unit", a convenient measure of the total amount
of ozone in a column overhead, is named in his
honor.
• Every 0.01 millimeter thickness of the layer is
equal to one Dobson Unit. The average amount
of ozone in the stratosphere across the globe is
about 300 DU.

9. Ozone “Hole”
• The Ozone Hole is not actually a Hole in the ozone
layer, but it is an Area where the total amount of ozone
is less then 200 DU.
• The Ozone Hole is Steadily increase in size about 27
Million sq. km.
• During 4 months each year half of the ozone layer
above Antarctica is depleted
• In 1984 researchers discovered 40-50% reductions in
later winter (August – November)

10. Effects of Ozone Layer
Depletion
-- Skin Cancer (melanoma and
nonmelanoma)
-- Premature aging of the skin
and other skin problems.
-- Cataracts and other eye
damage.
-- Immune system suppression.

11. Record ozone hole, 2006

12. What can we do?
• Make sure that technicians working on
your car air conditioner, home air
conditioner, or refrigerator are certified by
an EPA approved program to recover the
refrigerant (this is required by law).
•
• Have your car and home air conditioner
units and refrigerator checked for leaks.
When possible, repair leaky air
conditioning units before refilling them.

13. What can we do?
• Protect yourself against sunburn. Minimize
sun exposure during midday hours (10 am to
4 pm). Wear sunglasses, a hat with a wide
brim, and protective clothing.
• Use mass transit, walk, bicycle, and/or
reduce driving, especially on hot summer
days.
• Participate in your local utility's energy
conservation programs.

14. If all of the ozone-
depleting substances
were banned tomorrow,
it would take about 90-
150 years for Earth to
recover.