Chlorofluorocarbons (CFCs) are a group of chemical
compounds that has been shown to have caused the ozone
holes in the stratosphere over both the North and
South poles. A seasonal hole appears above Antarctica
in September.
These holes in the atmosphere allow the sun’s rays to
enter the earth without a protective layer to shield
us, which may cause an increase in skin cancer.
CFCs are an aggregation of chemical compounds that
include alkanes and haloalkanes. These chemicals are
used in aerosol spray cans, refrigerants, foam blowing
(to make packing foam and foam cups), fire
extinguishers and solvents to clean electronic
equipment.
The use of CFCs began in the 1920, when carbon
tetrachloride was used in fire extinguishers, until
the end of World War II. In 1928, Thomas Midgley
developed CFCs as a replacement for a mixture of
ammonia, chloromethane and sulfur dioxide that was
commonly used as a refrigerant.
The CFC was superior to the former compounds because
it was non-toxic, had a low boiling point and was
generally non-reactive.
CFCs continued to be used, mostly by the military and
in firefighting, until 1974 after the journal, ¬Nature
by Molina and Rowland, showed their findings regarding
the ozone layer depletion. They won the Nobel Prize in
Chemistry for that work.
They found that by adding hydrogen and creating
hydrochlorofluorocarbons (HCFC), made the compound
less stable in the lower stmosphere, which meant they
would break down before they reached the ozone layer.
Eventaully, the chlorine would be taken out, creating
HFC with an even less stable compound.
Scientists show that the decreases in CFCs have been
helping the ozone layer, particularly over Antarctica,
and predict that that particular hole will close
permanently by the year 2050.
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