Ozone is a
relatively unstable form of molecular oxygen
containing three oxygen atoms and is also known
as O3. Ozone is created when atmospheric oxygen
is broken down by sun's ultraviolet light, the
freed oxygen atoms bond with oxygen molecules to
form ozone.
Ozone near the surface
of Earth is considered a pollutant as If
ingested at higher concentrations it is known to
reduce human lung capacity, as well damage the
cells of living plants and animals. It is created
from industrial processes, transportation,
and some natural sources. It is also one of the
greenhouse gas which causes global warming.
However, Ozone in
ozone layer ( Stratosphere) plays a very important role.
The layer of ozone filters out incoming ultra
violet radiation which are harmful to living
cells. Without ozone, life on Earth would
not have evolved the way it has. The discovery
of a large ozone hole over Antarctica and its
association with man-made CFCs led the world to
take action to protect the ozone layer.
Concentrations of ozone in the stratosphere fluctuate
naturally in response to variations in weather
conditions and amounts of energy being released from the
Sun, and to major volcanic eruptions. However, in 1970s
it was realized that man-made emissions of CFCs and other
chemicals used in refrigeration, aerosols and cleansing agents
may be causing a significant destruction of ozone in the
stratosphere, thereby letting through more of the harmful
ultraviolet radiation pass through it and reaching the Earth.
In 1985 evidence of a large "ozone hole" was discovered
above the continent of Antarctica. This hole has been growing
larger and deeper each year. More recently, fears have
emerged about significant ozone depletion over the Arctic,
closer to the more populous regions of the Northern Hemisphere
as well. It has been realized that Ozone layer is being
depleted due to man made gas emissions such as CFC's.
What
are CFC's ?
CFCs or
Chlorofluorocarbons are widely used as
coolants in refrigeration and air
conditioners, as solvents in cleaners,
particularly for electronic circuit
boards, as a blowing agents in the
production of foam (for example fire
extinguishers), and as propellants in
aerosols.
Man-made CFCs are the main cause of
stratospheric ozone depletion. CFCs have
a lifetime in the atmosphere of about 20
to 100 years, and consequently one free
chlorine atom from a CFC molecule can do
a lot of damage, destroying ozone
molecules for a long time.
Why
we need Ozone layer?
Protecting the ozone layer
is essential. Ultraviolet radiation from the Sun can
cause a variety of health problems in humans, including
skin cancers, eye cataracts and a reduction in the
body's immunity to disease. Furthermore, ultraviolet
radiation can be damaging to microscopic life in the
surface oceans which forms the basis of the world’s
marine food chain, certain varieties of crops including
rice and soya, and polymers used in paints and clothing.
A loss of ozone in the stratosphere may even affect the
global climate.
Montreal
Protocol
In response
to fears about more widespread global
ozone depletion, the Montreal Protocol
on Substances that Deplete the Ozone
Layer was implemented in 1987. This
legally binding international treaty
called for participating developed
nations to reduce the use of CFCs and
other ozone depleting substances. In
1990 and again in 1992, subsequent
Amendments to the Protocol brought
forward the phase out date for CFCs for
developed countries to 1995.
more..
How Ozone Layer is being
affected?