(Effects of Reduction)
1% Reduction In O3 2% increase in UV-B
Skin sunburns, tans, Skin cancer
Absorbed by DNA DNA damage
Possible eye cataracts
Interferes with photosynthesis
Organisms in 1st 5metre of the Oceans at risk
( phytoplankton in particular )
Destruction of the Ozone Layer discovered in 1970’s by CFC’s ( Chlorofluorocarbons)
First synthesized Swartz (1892)
Used as refrigerants 1928 (Midgely & Henne)
CCl4 + xHF CCl(4-x)Fx + HCl
(Aerosol Propellants & Air conditioners)
O2 + h 2O.
O. + O2 O3
O3 + h O. + O2
Destruction CFCl3 Cl. Chlorine
(UV-C, UV-B) Radical
Cl. + O3 O2 + ClO.
ClO. + O. Cl. + O2
ClO. + ClO. ClOOCl (relatively stable)
CFC’s are now under strict control and their use has been curtailed.
Australia signed the international treaty.
“The Montreal Protocol“ in June 1988 which has a program controlling the use and reduction of CFC’s.
CFC- 11 CFCl3 Refrigeration, aerosol, foam
CFC-12 CF2Cl2 sterilization, cosmetics
food freezing, pressurized
CFC-113 CCl3CF3 solvent, cosmetics
Halon 1301 CBrF3 fire fighting (discontinued)
Compound Ozone Depleting Lifetime(yrs) Potential
CFC- 11 1.0 65 -75
CFC-12 1.0 100 - 140
CFC-113 0.8 100 - 134
CFC-115 0.6 500
CCl4 1.2 50 - 69
Halon 1301 10 110
( 90 Rule)
CFC’s name is related to its Formula.
CFC 123 123 + 90 = 213
The remaining bonds are allocated to Cl or Br
C = 2 , H =1 , F = 3 , Cl = ( 8 - 6) = 2
CFC 123 is CF3CHCl2
Letters with the number indicate an isomer.
Evidence for the destruction has been linked to the catalytically active Chloro monoxide ClO. & Ozone profiles as one goes South.
It is interesting to note how little Chloro monoxide effects the amounts of Ozone.