CFC (chlorofluorocarbon) is an organic
compound, that is composed of carbon (C), fluorine (F) and chlorine (Cl). This
chemical was invented in 1928 by Thomas Midgely, who was an American engineer
and he was looking to discover a non-toxic refrigerant, because at that time
people used ammonia and sulfur dioxide as a refrigerant. Then it was massively
used in 1960’s. Mostly CFC was used for refrigerators, automobiles and
air-conditioning.

 

            Ozone layer is a layer of the
earth’s atmosphere, approximately at 32 to 48 kilometers. The high ozone
content blocks most of the sun’s ultraviolet, in order to prevent it entering
into the lower atmosphere (troposphere). When CFC is released into
the atmosphere, it is broken down by the ultraviolet in the stratosphere. After
that it is broken down and it forms a free
radial – “An atom or group of atoms that has at least one unpaired electron
and is therefore unstable and highly reactive”.

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 (“free radical in
Science”), which plays a major role
in the ozone destruction.

 

            In 1970s scientists had theorized that CFC could be
harmful to the ozone layer, and it could lead to the ozone depletion.

Furthermore, in May 1985 British Antarctic Survey scientists (Joseph Farman,
Brian Gardiner, and Jonathan Shanklin) have discovered the huge hole in the
ozone layer.

 

The ozone layer depletion increases the amount
of ultraviolet, that gets to the Earth’s surface. The increased amount of the
UV in the ozone layer leads to skin cancer and also ruins early
developmental stages of the aquatic animals. After studying the bad effects of UV
radiation, the Montreal Protocol was created, and it was signed in September
1987. The concept of this treaty is to protect the ozone layer, from ozone
depleting chemicals.

In late 1960s,
scientists didn’t know, that CFCs could affect the ozone layer. Then in 1970
James Lovelock from UK became the first scientist to detect the CFC’s influence
on ozone layer. The second person, who made an influence on this problem was
Susan Solomon. In 1986, she and the National Ozone Expedition (NOZE) went to
the McMurdo station in Antarctica to make the first measurements
of chlorine and nitrogen, containing gases and prove the Lovelock’s theory. They
used a ground-based visible absorption technique in order to measure the ozone
level and the nitrogen dioxide, and chlorine dioxide emissions. In the end, the
NOZE’s and Susan’s experiment ended successfully, leading to a conclusion, that
CFC is the ozone depleting substance.

 

After the Montreal Protocol was created, CFCs were replaced by HFCs
(hydrofluorocarbons) and HCFCs (fluorocarbons). Although,
these chemicals don’t lead to ozone depletion, but they could lead to global
warming.

 

The levels of ozone depleting chemicals increased
a lot before the Montreal Protocol was signed. Right now, the number of these substances
in the atmosphere decreased. However,
the scientists say that the small extent of the ozone hole is not the sign of
healing, it is a sign of natural changeability.