1. Dr. Paul T Francis, MD Prof. Com. Med. College of Medicine, Zawia
Ozone depletion
Dr. Paul T Francis, MD
Prof. Com. Med.
College of Medicine, Zawia

2. single-day, measuring 29.5 million square kilometres
The size of Antarctic Ozone hole on September 24, 2006 was a record for a
single-day, measuring 29.5 million square kilometres

3. Contents Ozone production Dangers of Ozone depletion
Distribution of Ozone
Role of Ozone
Mechanism of Ozone depletion
Prevention of Ozone depletion
Greek – ozein=smell (Ozone has a pungent odor)

6. Ozone cycle
In the troposphere ozone is produced by chemical reaction between natural gases and polluting gases in the presence of sunlight
Ozone reacts with various chemicals (Chlorine and Bromine) and splits into O2 and O (atomic oxygen)
The overall Ozone content depends on the balance of photochemical production and Ozone destruction.

7. Good and ‘Bad’ Ozone
Ozone in the Stratosphere is protective and hence considered good.
Ozone in the Troposphere have some harmful effects
Lung damage, cough, chest pain in humans
Damage plants and reduce crops

9. Harmful effects of UV (Ultra Violet) B radiation
Human beings
Skin cancer
Cataract
Immune suppression
Plants
Single cell organism (plankton)
Aquatic ecosystem

13. Sources of ‘Halogen source gas’
Chlorofluorocarbons (CFC) producing Chlorine – Refrigerators, Air conditioners, aerosol sprays etc.
Halons producing Bromine – Fire extinguishers
Methyl Bromide and Methyl chloride are produced by nature

22. Prevention of Ozone depletion
“Montreal Protocol on Substances that Deplete the Ozone Layer” -1987
Provides legal limit on the production and consumption of ozone-depleting gases
By 2010 production of all ozone depleting chemicals have to be stopped
By 2050 we expect the ozone hole to disappear

23. Prevention cont’d
Chlorofluorocarbons to be substituted by HydroChloroFluroCarbons and by 2040 by HydroFluroCarbons

24. Summary
Ozone in Stratosphere is important for protecting us from harmful UV rays
Ozone is produced in nature by the action of UV rays on Oxygen
Halogen producing chemicals destroys Ozone in the Stratosphere leading to ozone depletion
The Montreal protocol has succeeded in reducing the production of CFCs and has very effectively reduced loss of Ozone