Ozone

LayerDepletion

“Life’s Support System

Depletion”

Outline of Presentation What is the Ozone layer?How is ozone created and

destroyed?What is the Ozone hole?What are the causes of Ozone

Depletion?

Outline of Presentation What are Ozone Depleting Substances?

Effects of the depleting Ozone to humanity and all

living things.

Impacts of the Ozone Layer depletion to the

Earth.

How can the Ozone layer be saved?

What is Ozone Layer?The Ozone Layer is a thin, fragile shield that envelops the entire earth which efficiently and effectively filters and screens almost all of the harmful ultraviolet rays.

air molecules

Ozone is a gas that is naturally present in the atmosphere.It is a molecule made up of three oxygen atoms.It’s chemical symbol is O3.

The Atmosphere Earth’s atmosphere is divided into four layers with different elevation and temperature profile:

1. Troposphere2. Stratosphere3. Mesosphere 4. Thermosphere

THE GOOD AND BAD OZONE

The Solar Radiation The Earth’s atmosphere is exposed to radiation from the sun. Energy is transferred from the sun to the earth in the form of electromagnetic energy. Electromagnetic energy can be divided into spectrum, in which protons that transfer energy have both a wavelength and energy level.

This radiation includes ultraviolet, visible and infrared radiations.

There are three categories of UV:

UV-A: Most UV-A is able to reach the earth’s surface. UV-B: 90% of UV-B is blocked off by the ozone layer. UV-C: 100% of UV-C is blocked off by the ozone layer.

HOW IS OZONE

CREATED AND

DESTROYED?

7HOW OZONE IS CREATED IN THE

STRATOSPHERE

UV radiation strikes ozone molecule…

… releasing one oxygen atom

O O

O

O

O O

How ozone is naturally destroyed in the Stratosphere

3

The depletion or the loss of the blocking effect of the ozone layer against ultraviolet rays is what we call the OZONE HOLE.

What is the

What causes the ozone layer

to deplete?

The Ozone Depletion Degradation of the Ozone

Layer.

When even a small amount of ozone layer is lost, more ultraviolet light from the sun can reach and destroy the Earth.

Caused by the chemical reaction involving chlorine and bromine which are also called Ozone Depleting Substances (ODS).

OZONE DEPLETING SUBSTANCES (ODS) AND THEIR USES

CHLOROFLUOROCARBONS or CFCs

HALONS• Simple chemicals containing

chlorine, fluorine and carbon.• CFCs are used in refrigerators, air-conditioners, spray cans, solvents, foams, other application.

• Contain at least one bromine atom• Halons are primarily used in fire extinguishers

OZONE DEPLETING SUBSTANCES (ODS) AND THEIR USES

OZONE DEPLETING SUBSTANCES (ODS) AND THEIR USES

HYDROBROMOFLUOROCARBONS (HBFCs) are used in fire extinguishers.

CARBON TETRACHLORIDE and METHYL CHLOROFORM are used as solvents.

HYDROCHLOROFLUOROCARBONS (HCFCs) were developed as the first major CFC replacement .

OZONE DEPLETING SUBSTANCES (ODS) AND THEIR USES

• METHYL BROMIDE (CH3Br) is used as a fumigant and in quarantine treatment.