Ozone hole is shrinking, a large hole over the Antarctic.

ozone layer


First Ozone depletion was noticed in 1970s and noticed that about 4% of ozone decreased. This events mainly occur in stratosheric ozone layer above the polar regions. Ozone layer is important for us because it protect us from harmful ultraviolet radiation.

Materials that causes ozone depletion are solvents, manufactured halocarbon refrigerants, CFCs (chlorofluorocarbons), HCFCs and other materials, these materials are known as Ozone Depleting Substances (ODS). Once these substances reach the stratosphere they release atoms and breakdown ozone (O3) in to oxygen (O2) causes depletion or formation of ozone hole.


For protection of Ozone layer UN adopt the Montreal Protocol in 1987, this act entered in force on 1 Jan 1989. This act bans the production of CFCs, HCFCs, halons, and other ozone depleting substances. Till date Montreal Protocol is one of the international environmental successful act.

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What is Ozone?

Ozone layer is O3 molecule, made up of three oxygen atoms. This layer is present in stratosphere, between troposhere and mesosphere. It acts as filter of our Earth. It protects our Earth by harmful ultraviolet radiation and cosmic radiation.

Ozone layer is measured in Dobson Units abbreviated as “DU”.

About 70% of ozone layer reduce over Antarctica, first noticed in 1985. NASA states that ozone layer was weak in 1990s, it is now recovering and it will fully recover by 2070.

ozone cycle
The Ozone cycle  Ozone_cycle.jpg: created by NASA derivative work: Smartse (talk) – Ozone_cycle.jpg

Effects of ozone depletion

As ozone layer absorbs UV rays from the sun leads to increase in UVB levels causes damage of skin in extreme causes skin cancer.

There are three types of UV radiation

Ultraviolet A, Ultraviolet B, Ultraviolet C

Biological effects

Biological effects includes

  1. Basal and squamous cell carcinoma
  2. Malignant melanoma
  3. Increased in production of vitamin D
  4. Cataract
  5. Effects on animal
  6. Effects on crops

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The ozone hole — it’s not really a hole, is it?

There is no hole there rather than there is ozone depletion over the Antarctic. It is also referred to as a “dramatic thinning” of ozone, shows in (August-October).

There are “mini-holes” and other aberrations in the northern hemisphere, too.

Edited by: Dr. Swapnil Surwase

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