THE OZONE LAYER AND ITS

DEPLETION

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• The atmosphere is divided into five layers. It

is thickest near the surface and thins out with

height until it eventually merges with space.

• 1) The troposphere is the first layer above the

surface and contains half of the Earth's

atmosphere. Weather occurs in this layer.

• 2) Many jet aircrafts fly in the stratosphere

because it is very stable. Also, the ozone

layer absorbs harmful rays from the Sun.

• 3) Meteors or rock fragments burn up in the

mesosphere.

LAYERS OF THE

ATMOSPHERE

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• 4) The thermosphere is a layer with auroras. It is also where the space shuttle orbits.

• 5) The atmosphere merges into space in the extremely thin exosphere. This is the upper limit of our atmosphere.

Ozone

layer

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Ozone is…

Ozone is a form of oxygen with 3 oxygen atoms (O3).

The oxygen we breath

has 2 atoms of oxygen

(O2).

Ozone is…

• 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 is…

It is thinnest around the equator and denser at the poles.

Dobson Units

• Ozone levels are reported in Dobson Units (DU).

• 300 DU is an average value.

Ozone…

• Ozone is very highly reactive and

will combine with other

substances easily.

• Near the earth's surface, these

reactions cause rubber to crack

and damage people's lung

tissues.

• Inhaling ozone can damage the

respiratory tract, which enables

us to breathe.

Ozone…

Ozone also

stunts plant

growth. That

hurts farmers,

agriculture,

and our

economy.

What is the ozone layer?

Most of the planet’s

ozone hangs out in

the Stratosphere,

the layer above the

Troposphere.

What is the ozone layer?

• Ozone in the stratosphere protects people,

animals, and plants from harmful ultraviolet rays.

• The ozone layer is a layer of gas consisting

of O3 molecules, called ozone, that forms

when free Oxygen molecules bond to O2

molecules.

So, why is the ozone layer

important to life on Earth?

• The stratospheric ozone

layer completely stops the

penetration of UV-C rays

and eliminates most of the

UV-B rays.

• Therefore, the ozone layer

protects life on Earth from

the harmful effects of

solar radiation on a daily

basis.

What’s Eating the Ozone?

• Scientists in the 1960s realized that something was going wrong in the ozone layer.

• They soon figured out that human actions were damaging Earth's shield against harmful radiation.

• Ozone in the troposphere is produced when sunlight and heat react with

nitrous oxides and volatile organic compounds, known as ozone precursors.

• These pollutants are emitted by vehicles, power plants, refineries, and

chemical plants.

• The amounts of “good” and “bad” ozone in the atmosphere depend on a

balance between processes that create and destroy ozone; an upset in this

balance has serious consequences for life on Earth.

Source: EPA

Ozone Destruction

Source: NASA

CFCs man-made

CFCs man-made

man-made

man-made

CFCs man-made

Source:theozonehole.com

CFCs and Ozone

So what about the hole in the

ozone layer?

October

1979

October

2007

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.

What causes 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.

• Today, no spray cans contain CFCs. Other chemicals are gradually replacing the CFCs in air conditioners.

Ultraviolet Radiation

The depletion of the ozone layer leads to higher levels of

ultraviolet radiation reaching Earth's surface.

This in turn can lead to a

greater incidence of skin cancer, cataracts, and impaired immune systems, and is expected also to reduce crop yields, diminish the productivity of the oceans, and possibly to contribute to the decline of amphibians that is occurring around the world.

What is the Montreal Protocol?

• The Montreal Protocol is a landmark international agreement designed to protect the stratospheric ozone layer.

• 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.

What can we do, as concerned citizens, to

ensure that our children have a viable planet

to inhabit?

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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What can we do?

• Make sure that technicians working on your car air

conditioner, home air conditioner, or refrigerator

are certified by an EPA approved program to

recover the refrigerant (this is required by law).

• Have your car and home air conditioner units and

refrigerator checked for leaks. When possible,

repair leaky air conditioning units before refilling

them.

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What can we do?

• Contact local authorities to properly dispose of

refrigeration or air conditioning equipment.

• Protect yourself against sunburn. Minimize sun

exposure during midday hours (10 am to 4 pm).

Wear sunglasses, a hat with a wide brim, and

protective clothing with a tight weave. Use a

broad spectrum sunscreen with a sun protection

factor (SPF) of at least 15 and 30 is better.

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Sources of Volatile Organic

Carbons

EGEE 102 - Pisupati 28

What can We do?

• Keep your automobile well tuned and maintained.

• Carpool, use mass transit, walk, bicycle, and/or

reduce driving, especially on hot summer days.

• Be careful not to spill gasoline when filling up

your car or gasoline-powered lawn and garden

equipment. During the summer, fill your gas tank

during the cooler evening hours.

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What can we do?

• Make sure your car's tires are properly inflated and

your wheels are aligned.

• Participate in your local utility's energy

conservation programs.

• Seal containers of household cleaners, workshop

chemicals and solvents, and garden chemicals to

prevent VOC from evaporating into the air.

Dispose of them properly.

LET US WORK TOGETHER FOR A BETTER AND SAFER

FUTURE

THANK YOU

BY

MANAGER

HEALTH AND

ENVIRONMENT

DPS,B.S.CITY