OZONE LAYER DEPLETION

Ozone is… Ozone is a form of oxygen with 3 oxygen atoms (O3).Ozone is highly corrosive and toxic and is used as a disinfectant.

It can be found in small concentrations in the troposphere where it is considered a pollutant.

Ozone at ground level is a pollutant.Ozone layer at stratosphere serves an important function

• The existence of ozone (O3 : 3 oxygen atoms) is a natural process in the atmosphere. The earth's atmosphere is composed of several layers.

• We live in the "Troposphere" where most of the weather occurs; such as rain, snow and clouds. Above the troposphere is the "Stratosphere"; an important region in which effects such as the Ozone Hole and Global Warming originate. Supersonic jet airliners such as Concorde fly in the lower stratosphere whereas subsonic commercial airliners are usually in the troposphere. The narrow region between these two parts of the atmosphere is called the “Tropopause”. Ozone forms a layer in the stratosphere, thinnest in the tropics (around the equator) and denser towards the poles.

•It's ironic that at ground level, ozone is a health hazard - it is a major constituent of photochemical smog. However, in the stratosphere we could not survive without it. Up in the stratosphere it absorbs some of the potentially harmful ultra-violet (UV) radiation from the sun which can cause skin cancer and damage vegetation, among other things.

How is Ozone Formed

WHAT IS OZONE LAYER The ozone layer refers to a region of Earth's stratosphere that absorbs most of the Sun's

ultraviolet (UV) radiation. It contains high concentrations of ozone (O3) relative to other parts of the atmosphere. The ozone layer contains less than 10 parts per million of ozone

The ozone layer absorbs 97–99% of the Sun's medium-frequency ultraviolet light (from about 200 nm to 315 nm wavelength), which otherwise would potentially damage exposed life forms near the surface

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

CAUSES OF OZONE DEPLETION The Ozone Hole is caused by chemicals called CFCs,

short for chlorofluorocarbons. CFCs escape into the atmosphere from refrigeration and propellant devices and processes, and they are so stable they last for decades. This long life allows some CFCs to eventually reach the stratosphere. The chemicals that make up CFCs, mainly chlorine and fluorine, float around the stratosphere, breaking up ozone molecules.

One molecule of CFC can destroy more than 100,000 molecules of stratospheric ozone.

Natural Causes include Volcanic eruptions, as they release carbon monoxide and decrease nitrogen oxides in the atmosphere., Methane from rotting vegetation etc.

CAUSES OF OZONE DEPLETION

OZONE DEPLETION PROCESS

WHAT IS THE OZONE HOLE?• The ozone hole is not technically a

“hole” where no ozone is present, but is actually a region of depleted ozone in the stratosphere over the Antarctic that happens at the beginning of Southern Hemisphere spring (August-October).

• The average concentration of ozone in the atmosphere is about 300 Dobson Units; any area where the concentration drops below 220 Dobson Units is considered part of the ozone hole.

WHO DISCOVERED THE OZONE HOLE?

• The Antarctic Ozone Hole was discovered in 1985 by British scientists Joseph Farman, Brian Gardiner, and Jonathan Shanklin of the British Antarctic Survey.

• The Ozone Hole has steadily grown in size (up to 27 million sq. km.) and length of existence (from August through early December) over the past two decades.

OZONE HOLE OVER THE YEARS

EFFECTS OF OZONE LAYER DEPLETION Ozone layer absorbs most of the harmful UV-B radiation; The

depletion of the ozone layer leads to higher levels of ultraviolet radiation reaching Earth's surface. More of ultraviolet radiation means: more melanoma and non-melanoma skin cancers more eye cataracts weakened immune systems reduced plant yields damage to ocean eco-ecosystems Large amounts of UV radiation can kill plankton found in oceans, which

absorbs carbon dioxide, thus increasing the rate of global warming.

EFFECTS OF OZONE LAYER DEPLETION

SOLUTIONS: PROTECTING THE OZONE LAYER

CFC substitutes Legislations like Montreal Protocol

ALTERNATIVES TO CFCS

The use of propane and 2-methyl propane as refrigerant coolants

Although their use would reduce ozone depletion, both hydrocarbons are flammable and are greenhouse gases

Fluorocarbons are not toxic or flammable and are stable to uv reactions, although they are greenhouse gases

Hydro chlorofluorocarbons are more stable than CFCs, but they are only a temporary solution since the C-Cl bond is still present

Hydro fluorocarbons are the best alternative because there is no chlorine atom present

MONTREAL PROTOCOL

•The Montreal Protocol is an international agreement adopted in 1987 to control the production and consumption of specific man-made chemicals that destroy the ozone layer, the earth’s protective shield. •The Montreal Protocol says that the production and consumption of compounds that deplete ozone in the stratosphere--chlorofluorocarbons (CFCs), halons, carbon tetrachloride, and methyl chloroform--are to be phased out by 2030.•Montreal Protocol adopted in 1987191 countries have signed the Montreal Protocol including all the CARIFORUM countries•India signed the Montreal protocol on 19th June, 1992

MONTREAL PROTOCOL

Avoid using and buying products that might be made with CFCs

For example: use a reusable cup instead of a plastic foam one.

Have home and car air conditioners checked for leaks

Use air conditioners only if needed for health or safety reasons.

When serving your car, take it to a station that can recycle the air conditioning coolant

Make sure that old refrigerators and air conditioners are disposed of safely by giving them to a recycling yard. Take care not to damage the cooling circuit which contains the ODS.

HOW CAN WE MAKE A DIFFERENCE

September 16 was designated by the United Nations General Assembly as the International Day for the Preservation of the Ozone Layer.This designation was made on December 19, 1994, in commemoration of the date, in 1987, on which nations signed the Montreal Protocol on Substances that Deplete the Ozone Layer.

International Day for the Preservation of the Ozone Layer

FUTURE EVOLUTION OF OZONE Remains unclear

Current models are unable to reproduce ozone variability accurately

Rates of future increases in greenhouse gases are not yet established

Interactions between ozone depletion and climate change not yet fully understood

Continued monitoring of ozone and ozone-depleting substances is essential Ozone layer recovery expected by 2050 Hinges on the complete elimination of atmospheric ozone-

depleting substances Replacements for HCFCs, methyl bromide, and halons are still

being sought, and studies of the new compounds must continue

(U.N.E..P. Progress Report, 2003)

EFFORTS NEED TO BE CONTINUED Create reliable models

To gain a better understanding of the effects ozone depletion has on organisms living within different ecosystems

Enforcement of Montreal Protocol To reduce concentrations of chemicals responsible for

ozone depletion Monitoring chemicals being emitted

Gain a better overall understanding on just how ozone depletion is affecting our planet

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