OZONE DEPLETION

BY SANDEEP KUMAR

WHAT IS OZONE LAYER?

The ozone layer is a layer in Earth's atmosphere containing relatively high concentrations of ozone (O3).

It is unlike the oxygen we breathe, which are diatomic molecules, meaning 2 oxygen atoms(O2).

Ozone is a corrosive, light blue gas with a smell something like burning electrical wiring.

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O2+O --> O3

Where is ozone layer located?

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The ozone layer is mainly found in the lower portion of the stratosphere from approximately 17 to 50 kilometres (9 to 30 mi) above Earth, though the thickness varies seasonally and geographically.

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IT IS DISCOVERED BY?

The ozone layer was discovered in 1913 by the french physicists Charles Fabry and Henri Buisson.

Its properties were explored in detail by British Meteorologist G.M.B Dobson, who developed a simple Spectrophotometer(the dobsonmeter).

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It is used to measure the stratospheric ozone from the ground.

 Between 1928 and 1958 Dobson established a worldwide network of ozone monitoring stations, which continue to operate to this day.

The "Dobson unit", a convenient measure of the columnar density of ozone overhead, is named in his honor.

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The ozone layer absorbs 97–99% of the Sun's medium-frequency ultraviolet light (from about 200 nm to 315 nm wavelength), which potentially damages exposed life forms on Earth.

When the layer is thin or damaged this ultraviolet radiation can cause eye cataracts, skin cancers and damage to crops. 

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How ozone layer protects us?

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OZONE DEPLETION

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Destruction of upper atmospheric level of ozone layer.

The fact that the ozone layer was being depleted was discovered in the mid-1980s. The main cause of this is the release of CFCs, chlorofluorocarbons.

In recent years, the ozone layer has been the subject of much discussion. And rightly so, because the ozone layer protects both plant and animal life on the planet.

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CAUSE OF OZONE LAYER DEPLETION ?

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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.

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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

ODS have a long lifetime in our atmosphere — up to several centuries.

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The Main Ozone-Depleting Substances (ODS)

Chlorofluorocarbons (CFCs) – Used as coolants in refrigerators & air conditioners.

Halons - Used in some fire extinguishers. Methyl Chloroform - Used mainly in industry for

vapour degreasing, some aerosols, cold cleaning, adhesives and chemical processing.

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Carbon Tetrachloride – used in solvents and some fire extinguishers.

Hydrofluorocarbons (HCFCs) – Used as substitutes of (CFCs) less harmful than (CFCs) but still cause some ozone destruction.

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EFFECTS OF OZONE EFFECTS OF OZONE LAYER DEPLETION ?LAYER DEPLETION ?

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Exposure to higher amounts of UV radiation could have serious impacts on human beings, animals and plants as follows:-

To human beings – Skin cancers, sunburns, cataracts, blindness & also weakens the human immune system.

To trees & agriculture – World’s major crops, plants & trees are vulnerable to UV, resulting in reduced growth.

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To Marine life – In particular, plankton (tiny organisms in the surface layer of oceans) are threatened by increased UV radiation. Plankton are the first vital step in aquatic food chains.

To Animals – UV overexposure may cause eye and skin cancers. Marine animals in their developmental stage have been threatened in recent years by the increased UV radiation under the Antarctic ozone hole. 

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What can you do to What can you do to prevent Ozone prevent Ozone layer depletion ?layer depletion ?

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The nations of the world have taken a crucial step in joining together to halt the production and use of ozone-destroying chemicals. But the work can't stop there.

Here's what you can do:- It is illegal to recharge refrigerators, freezers and

home/vehicle air conditioners with CFCs. Don't buy or use portable fire extinguishers that

contain halons.

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If you have an older vehicle with an air conditioner, have it serviced by a qualified technician, and make sure the CFC is recaptured and recycled by technician who is specifically certified to do this work. If you don't use your air conditioner — or if the vehicle is about to be scrapped — make sure a qualified technician recaptures and recycles the CFC. 

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OZONE DEPLETION A FURUTISTIC VIEW

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THANK YOU

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