Ozone layer or the stratospheric ozone is a layer of gas (O3) that partially shields the earth from the Sun’s ultraviolet (UV) radiation. In May 1985, Joseph Farman, Brian Gardiner and Jonathan Shanklin, scientists with the British Antarctic Survey shocked the world when they announced an enormous thinning in the ozone layer over Antarctica—the Ozone hole. Their data suggested that chlorofluorocarbons (CFCs)—used in air conditioners—were to blame : atmospheric conditions during the cold, dark, Antarctic winters were building stockpiles of CFCs over the South Pole. Scientist discovered that CFCs were eating away at this protective layer, exposing every person on Earth to higher risk of skin cancer, cataracts, and other illnesses. In September 1987, an international treaty aimed at saving the Earth’s ozone layer, known as the Montreal Protocol on Substances that Deplete the Ozone Layer, was signed in Montreal, Canada. The Protocol requires phasing out of the ozone depleting substances (ODS) in accordance with agreed schedules.
The good news is that, now the CFCs have been eliminated through the Montreal Protocol, the growth of ozone hole has significantly slowed and ozone layer has started to repair itself and to restore its capacity to shield us from diseases. By avoiding products and practices that damage the ozone layer and by lobbying for more action from government and industries, there is a hope to close the hole by the end of this century.
According to Scientists ozone depletion in the stratosphere is caused by ozone depleting chemicals. These chemicals contain chlorine or bromine atom with inherent chemical stability and have long lifetime in the atmosphere, in the range of 40 to 150 years. These chemicals and other trace gases drift up into the stratosphere and become involved in chlorine-releasing reactions. The chlorine atoms then react with the ozone molecules in the presence of sunlight and destroy the ozone molecules. Just one chlorofluorocarbon molecule can destroy tens of thousands of ozone molecules.
These ozone-depleting chemicals are extensively used man-made chemicals including the chlorofluorocarbons (CFCs); halons; 1,1,1-trichloroethane (methyl chloroform); carbon tetrachloride; methyl bromide; hydrobromofluorocarbons (HBFCs); hydrochlorofluorocarbons (HCFCs); and bromochloromethane (BCM).
There has been considerable progress in finding non-ozone-depleting substitutes for ODS in the last few years. Substitutes for air-conditioning and refrigeration applications are now available, such as that HCFC-22 can be replaced by HFC-410A; CFC-12 can be replaced by HFC-134a. There are also emerging markets for “drop-in” replacement for HCFCs and halons.
Alternative products or processes can be used in some cases including the, alternative insulating materials; substitute food containers such as hydrocarbon blown polystyrene, plastic film wrap and bags; alternative packaging materials such as plastic film bubble wraps; and air-conditioning and refrigeration plants operating on non-HCFC refrigerants.
HCFCs solvents can be substituted in some applications. For instance, petroleum solvents can be selected as a replacement for CFC-113 or 1,1,1-trichloroethane in cleaning applications. Aqueous cleaning, or even no-clean technology, is also alternative process that can be used by the electronics industry. Many household and personal aerosol products, e.g. paint sprays and insecticides, now use hydrocarbons (e.g. propane and butane) as propellants instead of HCFCs or CFCs.
We’re now seeing the introduction of the third generation of alternatives to CFCs. Some are new fluorocarbons, and some come from other chemical families. The new chemicals don’t hurt the ozone layer and have far less impact on the climate than their predecessors.
While the vast majority of ozone depleting substances usage is either industrial or commercial, individuals can help by using ozone friendly or CFC free products and ensure that they do not contain ODS such as CFCs or halons, HCFCs as under :
- Buy air-conditioning and refrigeration equipment that do not use HCFCs as refrigerant.
- Buy aerosol products that do not use HCFCs or CFCs as propellants.
- Conduct regular inspection and maintenance of air-conditioning and refrigeration appliances to prevent and minimize refrigerant leakage.
- For existing air-conditioning and refrigeration appliances that operate on HCFCs or CFCs, the refrigerant should be recovered or recycled whenever an overhaul of equipment is to be carried out. Replacing or retrofitting such equipment to operate on non-HCFCs refrigerant should also be considered.
- When motor vehicle air-conditioners need servicing, make sure that the refrigerants are properly recovered and recycled instead of being vented to the atmosphere.-S.K. Sachdeva
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