What is the Meaning of Depletion of Ozone Layer

What is the Meaning of Depletion of Ozone Layer

Ozone Depletion
The amount of ozone in ozonosphere began to drop in 1980s. A spring time ozone hole (area of extreme thinness of ozone) was discovered over Antarctica in 1985 by Farman et al. Its area has been spreading subsequently. An ozone reduction of 1% increases the amount of high energy UV–B radiations reaching the earth by 2%. It means that there has been increase in UV–B radiations reaching the earth by 15–20%.

ODS :
Ozone depleting substances or ODS are those substances which react with ozone present in the stratosphere and destroy the same. The main ozone depleting substances are chlorofluorocarbons (CFCs), halons, nitrous oxide, methane, carbon tetrachloride and chlorine. Chlorofluorocarbons are highly stable, odourless, synthetic gaseous substance used as aerosol propellants, coolants, refrigerants, blowing agents, etc.

CCl₂F₂  (UV radiation) →  CClF₂ + Cl
2Cl + O₃  →   Cl₂O + O₂
2Cl₂O   →   4Cl + O₂

Effects of Ozone Depletion :

1.  Cancers – The incidence of skin cancer and herpes would increases.
2.  Eye Sight – There will be dimming of eye sight, photoburning and higher incidence of cataracts.
3. Immune system – It will be impaired resulting in increasing number of diseases.
4. Mutations – More mutations will occur. Most of them would be harmful.
5. Photosynthesis – 10–25% decline in photosynthesis would occur.
6. Global warming – Reduced photosynthesis will increase CO₂ concentration causing global warming.
7. Damage to Articles