What is the ozone layer?

• The ozone layer is a deep layer in the stratosphere, encircling the Earth, that has large amounts of ozone in it. The layer shields the entire Earth from much of the harmful ultraviolet radiation that comes from the sun. 

•  Interestingly, it is also this ultraviolet radiation that forms the ozone in the first place. Ozone is a special form of oxygen, made up of three oxygen atoms rather than the usual two oxygen atoms. It usually forms when some type of radiation or electrical discharge separates the two atoms in an oxygen molecule (O2), which can then individually recombine with other oxygen molecules to form ozone (O3)
• Read more about  ULTRAVIOLET 

Why are we so concerned about the Ozone Layer?

• The Ozone Layer acts as a shield for us from very harmful UV rays. If we damage the Ozone Layer any more than we would put ourselves at an increasingly greater risk. Without the Ozone Layer we wouldn't be able to survive. Exposure to UV rays causes skin cancer, damages crops, and harms ocean life. 

• Without the Ozone Layer the risk of these things would greatly increase. An example of this is in Australia, where a large amount of ozone has depleted. Around 97% of the citizens have or have had skin cancer problems due to the exposure to harmful UV rays that leak through the Ozone layer.
• Another risk is polar shifting, a complex event that occurs when uneven melting of ice shelfs occur.
• A major hole is now over Antarctica, where there are ice shelfs. If these Ice shelfs melt, it could increase coastal flooding and the poles could shift, causing a violent shift in climate.

The Causes of Ozone Depletion

 

Scientific evidence indicates that stratospheric ozone is being destroyed by a group of manufactured chemicals, containing chlorine and/or bromine. These chemicals are called "ozone-depleting substances" (ODS).

ODS are very stable, nontoxic and environmentally safe in the lower atmosphere, which is why they became so popular in the first place. However, their very stability allows them to float up, intact, to the stratosphere. Once there, they are broken apart by the intense ultraviolet light, releasing chlorine and bromine. Chlorine and bromine demolish ozone at an alarming rate, by stripping an atom from the ozone molecule. A single molecule of chlorine can break apart thousands of molecules of ozone.

What's more, ODS have a long lifetime in our atmosphere — up to several centuries. This means most of the ODS we've released over the last 80 years are still making their way to the stratosphere, where they will add to the ozone destruction.

Hydrofluorocarbons (HFCs) are being developed to replace CFCs and HCFCs, for uses such as vehicle air conditioning. HFCs do not deplete ozone, but they are strong greenhouse gases. CFCs are even more powerful contributors to global climate change, though, so HFCs are still the better option until even safer substitutes are discovered.

The Main Ozone-Depleting Substances (ODS)

• Chlorofluorocarbons (CFCs)  
  • The most widely used ODS, accounting for over 80% of total stratospheric ozone depletion.
• Used as coolants in refrigerators, freezers and air conditioners in buildings and cars manufactured before 1995.
• Found in industrial solvents, dry-cleaning agents and hospital sterilants.
• Also used in foam products — such as soft-foam padding (e.g. cushions and mattresses) and rigid foam (e.g. home insulation).
• Halons
  Used in some fire extinguishers, in cases where materials and equipment would be destroyed by water or other fire extinguisher chemicals. In B.C., halons cause greater damage to the ozone layer than do CFCs from automobile air conditioners.
  
• Methyl Chloroform
  • Used mainly in industry — for vapour degreasing, some aerosols, cold cleaning, adhesives and chemical processing.
• Carbon Tetrachloride
  
  • Used in solvents and some fire extinguishers. 
• Hydrofluorocarbons (HCFCs)
  • HCFCs have become major, “transitional” substitutes for CFCs. They are much less harmful to stratospheric ozone than CFCs are. But HCFCs they still cause some ozone destruction and are potent greenhouse gases.

        HOW TO PROTECT OZONE LAYER ?

Ways to Protect the Ozone Layer:

1. Minimize high altitude aircraft flights (oxygen reduction and water vapor deposition)
2. Minimize rocket flights (water vapor deposition)
3. Encourage growth of plants that produce oxygen, discourage deforestation
4. Decrease / control releases of high temperature steam / moisture to the atmosphere
5. Eliminate production and release of known ozone depleting chemicals (such as CFCs and HCFCs) where remotely possible. Subsidize production of safer alternatives where possible.
6. Establish controls to assure that new compounds to be used in high volume, are surveyed for effect on ozone.

Actions an Individual Can Take (see the link below for more):

• Ensure technicians repairing your refrigerator or air conditioner recover and recycle the old CFCs so they are not released into the atmosphere.
• Vehicle air conditioning units should regularly be checked for leaks.
• Ask about converting your car to a substitute refrigerant if the a/c system needs major repair
• Help start a refrigerant recovery and recycling program in your area if none already exists.
• Replace halon fire extinguishers with alternatives (e.g. carbon dioxide or foam).
• Suggest school activities to increase awareness of the problem and to initiate local action.

       A SHORT VIDEO ON OZONE LAYER