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The Ozone Layer.

The ozone layer is a region in the Earth's stratosphere that protects life by absorbing harmful ultraviolet radiation. Ozone depletion, primarily caused by human-made chemicals like chlorofluorocarbons (CFCs), leads to thinning of this protective layer, resulting in increased UV radiation and associated health and environmental risks. The Montreal Protocol has been instrumental in phasing out the use of ozone-depleting substances, contributing to the recovery of the ozone layer.

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19 views11 pages

The Ozone Layer.

The ozone layer is a region in the Earth's stratosphere that protects life by absorbing harmful ultraviolet radiation. Ozone depletion, primarily caused by human-made chemicals like chlorofluorocarbons (CFCs), leads to thinning of this protective layer, resulting in increased UV radiation and associated health and environmental risks. The Montreal Protocol has been instrumental in phasing out the use of ozone-depleting substances, contributing to the recovery of the ozone layer.

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divyaanshim
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THE OZONE LAYER

AND ITS DEPLETION


WHAT IS THE OZONE LAYER?
THE OZONE LAYER IS A REGION IN THE EARTH'S STRATOSPHERE, ABOUT 15 TO
30 KILOMETERS ABOVE THE SURFACE, THAT CONTAINS HIGH CONCENTRATIONS
OF OZONE (O3).
ACTS AS A SHIELD, ABSORBING MOST OF THE SUN'S HARMFUL ULTRAVIOLET
RADIATION (MORE SPECIFICALLY UV-B), PROTECTING LIFE ON EARTH.

COMPOSED OF OZONE (O₃) MOLECULES, FORMED WHEN UV LIGHT SPLITS O₂


→
MOLECULES, AND SINGLE O ATOMS BOND WITH O₂ O₃.
STRUCTURE AND LOCATION
FOUND 15–35 KM ABOVE EARTH IN THE STRATOSPHERE.
COMPOSED OF OZONE (O₃) MOLECULES.

Thermosphere

Mesosphere
690 km
Stratosphere
8 km
Trophosphere
0zone 20 km
Formation of Ozone
Ozone (O₃) is formed in the stratosphere by the action of ultraviolet (UV) rays from
the Sun on oxygen molecules.

UV radiation splits an oxygen molecule (O₂) into two single oxygen atoms
Each single oxygen atom (O) reacts with another O₂ molecule to form ozone (O₃).

Dynamic Balance: Ozone is also continuously broken down by UV rays into O₂ and O,
maintaining a natural balance.
Result: This ozone-oxygen cycle absorbs most harmful UV-B and UV-C rays, protecting
life on Earth.
The Problem of Ozone Depletion
What is Ozone Depletion?

It is the thinning of the protective ozone layer in the stratosphere.


This process is not natural; it is caused by human-made chemicals.
The most significant sign is the "ozone hole," a severe thinning that occurs
seasonally over Antarctica.
The primary cause is the release of ODS into the
atmosphere.
The most common ODS are Chlorofluorocarbons (CFCs),
which were widely used in:
Refrigerators and air conditioners (as coolants).
Aerosol spray cans.
Foam blowing agents and solvents.
Stable CFCs don't break down in the lower atmosphere.
They travel to the stratosphere, where intense UV radiation breaks
them apart, releasing chlorine atoms (Cl).

A Catalytic Chain Reaction: A single chlorine atom can destroy


thousands of ozone (O3​) molecules in a cycle.

The reaction is:


→
Cl+O3​ ClO+O2​
→
ClO+O Cl+O2​
Harmful Effects
Increased UV Radiation leads to:
1. Higher rates of skin cancer and cataracts in humans.
2. Weakened immune systems.
3. Damage to crops, forests, and marine food chains (phytoplankton).

The Solution?
The Montreal Protocol is a significant international agreement. It successfully aimed to phase
out the production and use of ODS, leading to the slow recovery of the ozone layer.
THANK YOU!

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