sargaty

3. Ozone is a colorless gas,consist of 3 oxygen
molecules,found in the upper atmosphere of the Earth and
formed by the action of ultraviolet radiation on oxygen.
Ozone forms a layer in the stratosphere, which protects life
on Earth from the harmful effects of ultraviolet radiation.
The ozone layer is a region in the stratosphere, between
17 and 25 km above the earth’s surface.
Without the ozone layer WE WOULD ALL DIE (because UV
light kills all living tissue).
This layer absorbs about 97-99% of the harmfull UV rays.

5. Ozone Absorption in the UV Band
• UV radiation includes wavelengths from 200 to 400 nm
• UV-A 320-400 nm
• UV-B 200-320 nm
• UV-C 200-290 nm
• UV-C
• Nearly all UV-C is absorbed in the upper atmosphere
• UV-B
• 90% of UV-B is absorbed by the atmosphere, mostly by O 3
• UV-A
• Not strongly absorbed by the atmosphere

6. o Presence of chloroflurocarbones(CFCs)
o Hydrofluorocarbons (HCFCs): They are much less harmful to
stratospheric ozone than CFCs,But HCFCs they still cause some
ozone destruction and are potent greenhouse gases
o methyl chloroform (used in industry — for vapour degreasing,
some aerosols, cold cleaning, adhesives and chemical
processing)
o Presence of halons (used in fire extinguishers).
o Presence of oxides of nitrogen
o Presence of bromide such as methyl bromine (used as a
pesticide).
o Hydrogen chloride
o Carbon tetrachloride(industrial solvent)
o Hyrdobromofluorocarbon(HBFCs)
o Bromochloromethane(BCM)

11. What is CFC (freon)??
 A hydrocarbon or haloalkan that contain
chlorine,flourine and carbon atoms
 CFC or freon damage the ozone layer when released in
the envionment,but also saves lives by keeping food from
spoiling , fire fighting and sterilization of surgical tools.
 Non toxic
 Non-flammable
 Noncorrosive
 Inexpensive
 long-lived
“Dream Chemical”
 U.S government banned the production of freon.

12. • CFC-11 (trichlorofluoromethane - CFCl3)
• CFC-12 (dichloro-difluoromethane - CF2Cl2)
• CFC-113 (trichloro-trifluoroethane - C2F3Cl3)
• CFC-114 (dichloro-tetrfluoroethane - C2F4Cl2)
• CFC-115 (chloropentafluoroethane - C2F5Cl)

15. Air Conditioners
Refrigerators
Fire extenguisher
Spray cans
Pesticides
Insulation materials
Cleaners for electronic parts
Sterilizing medical instruments

18. United States accounts for largest part of world-wide
consumption o CFC’s
29% of global consumption of CFC is from US
Americans use six times more CFC’s than global
average
Vehicle air conditioners accounted for about
75% of annual CFC emissions in the US in 1990
Since 1978 the use of CFC’s in aerosol cans has
been banned in many countries; however,
worldwide, aerosol cans still account of 25% of
CFC emissions.

22. The Antarctic ozone hole was discovered in 1985 by British
scientists Joesph Farman, Brian Gardiner, and Jonathan Shanklin of
the British Antarctic Survey.

27. 400 Figure 21-22
350
Page 485
October monthly means
Total ozone (Dobson units)
300
250
200
150
100
1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Year

28. 100
200
300
400
1950
1960
1970
1980
1990
2000
1950
100
200
300
400
1950
1960
1960
1970
1970
1980
1980
1990
1990
2000
2000
100
200
300
400

30. ozone layer depletio (4).FLV

31. Skin cancer
Premature aging (photoaging) of the
skin
Sun burn

32. This long-wavelength (low-energy) form of UV This shorter-wavelength (high-energy) form of UV radiation
radiation causes aging of the skin, tanning, and causes sunburn, premature aging, and wrinkling. It is largely
sometimes sunburn. It penetrates deeply and may responsible for basal and squamous cell carcinomas and
contribute to skin cancer. plays a role in malignant melanoma.
Ultraviolet A Ultraviolet B
Hair
Thin layer of dead cells
Squamous cells Epidermis
Basal layer Sweat gland
Melanocyte cells
Dermis
Blood vessels
Basal cell
Squamous Cell Carcinoma Basal Cell Carcinoma Melanoma

37. Each 1% loss of ozone leads to a 2% increase in UV
radiation striking the earth.
A 2% increase in UV radiation results in a 5% to 7%
increase in skin cancer, including a 1% increase in
deadly malignant melanoma
An additional 940,000 cases annually of basal-cell
and squamous-cell skin cancer
An additional 30,000 cases annually of melanoma
skin cancer (often fatal). There are 9,000 American
deaths per year from this now.

38. Protect the skin against the solar radiation
using skin creams with SPF or other sunscreen.

41. • Stay out of the sun especially between 10 A.M
and 3 P.M
• Donot expose yourself to the sun if you are
taken antibiotics and contraceptive pills
• Examine your skin and scalp at least once a
month for moles or warts that change in
size,shape,color,or sores that keep
oozing,bleeding and crusting over.if you observe
any of this signs,consult a doctor immediately.

42. Solutions : Protecting the Ozone Layer
Stop producing CFCs or
Reduce emission of ozone deplating chemicals that
contains CFC.
Reduce the uses of aerosol sprays.
Uses of aerosol spray that is free
in CFCs compound instead.
properly recycle old CFCs
Use safe alternatives
Educate other governments
for environmental policies
Montreal Protocol 36 nations:
Goal: reduce CFCs by 35% by 2000
Copenhagen Protocol

43. http://www.bom.gov.au/lam/Students_Teachers/
ozanim/ozoanim.shtml
www.theozonehole.com/ozonedestruction.html
 australia.jrn.msu.edu/.../ozonepage.html
http://www.nas.nasa.gov/About/Education/Ozon
e/ozonelayer.html
http://www.bcairquality.ca/101/ozone-depletion-
intro.html
http://www.ozonedepletion.info/education/ozon
e.html