By: Gajan Balakumar, Cindy Guo, Warren Viegas, Muhammad
Bajwa, Komal Sandu & Sidarth Aiyar
AIMS OF THE RESEARCH
To investigate the reduction of Ozone in the
stratospheric region of the atmosphere caused
by the usage of Chlorofluorocarbons (CFCs).
Are CFCs guilty for the climate change during
the late 20th century?
What lessons can be learned from our
understanding of CFCs that can help us fight
ozone depletion in the future?
What alternatives are there for this compound?
THE MIRACLE CHEMICAL
CFCs were once known as „Miracle‟ Chemicals.
First manufactured in the 1930s, and
industries soon found a wide variety of
applications for them due to their chemical
unreactivity and heat-absorbing properties.
Used as refrigerant‟s in AC‟s and other objects.
THE MIRACLE CHEMICAL CONT’D
Are very handy in production since it cost less
and no real natural resources required for
Organic bonding of Halo-Carbons, performed
easily and efficiently in the labs.
Were given the household name “Freon‟s”.
Scientists initially believed that CFCs would be
harmless in the earth's atmosphere because of
their chemical inertness.
This and their lack of solubility in water, gives
CFCs a long life span in the atmosphere (tens
to hundreds of years)
However, in the stratospheric region of the
atmosphere, these molecule break down,
where the UV rays are intense.
THEIR MISTAKE CONT’D
The break down releases
Chlorine which act as catalysts
in the Ozone destruction
(Reactions shown later on).
The ozone layer is important to
humans and other life on earth
because it absorbs harmful UV
radiation (acting as a sort of
Long-term effects on humans'
excessive UV exposure include
skin cancer, eye damage
(cataracts), and suppression of
the immune system.
CFCs are completely manmade and produce
them for use in their machines.
The main method used to make CFCs is to take
a methane or ethane based compound that
has been chlorinated, i.e. has a chlorine
attached to it, and react it with HF.
The process to make the various types of CFCs
is the same. The reaction varies only slightly for
each different type of CFC.
Trichlorofluoromethane: CCl4 + HF →CFCl3 + HCl
Dichloro-difluoromethane: CCl4 + 2HF →CF2Cl2 + 2HCl
Trichloro-trifluoroethane: C2Cl6 + 3HF →C2F3Cl3 + 3HCl
Dichloro-tetrafluoroethane:: C2Cl6 + 4HF →C2F4Cl2 + 4HCl
Chloro-pentafluoroethane: C2Cl6 + 3HF →C2F5Cl + 5HCl
When CFCs reach stratosphere, dissolved by UV
light to release Chlorine atoms
Chlorine atoms act as catalyst --> each atom break
down tens of thousands of ozone molecules
before they exit stratosphere
CFCs take approximately 15 years to reach upper
atmosphere from ground level and stay there for
up to a century.
In 1973, chlorine found to be catalytic agent in
March 1985, announced there was polar ozone
depletion over Antarctica --> initiatives to freeze or
diminish production of CFCs
In 1980‟s, 30-40% decrease in stratospheric
By spring of 1987, 50% ozone gone over antarctic
In space, there is TOMS (total ozone mapping
spectrometer), which has shown downward trends
in ozone layer at all latitudes near tropics.
Greatest global warming potential among gases
which induce global warming because they are
CFCs absorb infrared radiation
Each CFC molecule absorbs tens of thousands as
much infrared radiation as Carbon Dioxide
CFC-11 is 3,000 - 12,000 as effective as carbon
CFC-12 is 7,000 - 15,000 as effective as carbon
CFCS RAPIDLY ENTERED THE OZONE LAYER
DURING THEIR USE
can lead to increase UVB light on humans:
cataracts --> major cause of blindness in world,
accounts for 50% of blindness (1994).
EFFECT ON PLANT
30-50% of all organisms affected by UVB light
--> therefore, change in UVB light can cause
mutations to organisms
Increased UV may cause reduction in
productivity of trees because it would affect
their uptake of carbon dioxide from the
atmosphere --> important because trees
accounts for 80% of plant biomass productivity
Coolants in refrigeration
and air conditioners
as solvents in cleaners
for electronic circuit
blowing agents in the
production of foam (for
propellants in aerosols.
The total U.S. production of chlorofluorocarbons
was estimated to be 737 million pounds in
Production of CFCs grew rapidly during the 20th
century, growing from 42 kilo tonnes in 1950 to
1260 kilo tonnes in 1988
After their harmful effect on the ozone layer
was discovered, production decreased to 147
kilo tonnes in 1999
A ban was imposed on the use of CFCs in aerosol-spray
dispensers in the late 1970s by the United States, Canada, and
the Scandinavian countries.
In 1990, 93 nations agreed to end production of ozone-
depleting chemicals by the end of the century.
In 1992 most of those same countries agreed to end their
production of CFCs by 1996.
However, production of CFCs is still going strong in the
developing world, particularly in South Asia, and Africa, as a
result of economic constraints
Each year Americans dispose of roughly 13 million refrigerators
and freezers and many of those contain chlorofluorocarbons
(CFCs) that deplete the ozone layer and contribute to climate
Their firm determination to take all appropriate
measures to phase-out the production and
consumption of all fully halogenated
chlorofluorocarbons controlled by the Montreal
Protocol, as adjusted and amended, as soon as
possible but not later than 1997.
London, 27-29 June 1990
THE UN’S SCHEDULE FOR REDUCTION OF CFC
Concentration of CFCs in ozone layer has begun to level off
FLUOROCARBONS, GLOBAL INDUSTRY AND
Fluorocarbons are the CFC replacement for the majority of the
producer and user industries.
Over US$25 billion has been invested in fluorocarbons to
Industry has played a vital role in developing alternatives
as long as chlorine and bromine
emissions continue to decline, ozone
levels in the stratosphere will return
to normal by the middle of next
continued use of these fluorocarbons
is actively encouraged to allow further
progress in CFC replacement,
especially in the developing world.
Fluorocarbons liquids are colorless. They have a high density due to
their high molecular mass, but less overall separation between F and
They comprise of Low and weak intermolecular forces; which gives it
low viscosity when compared to liquids of similar boiling point for e.g.
They are immiscible with most organic solvents (ethanol and
chloroform), but are miscible with hydrocarbons.
They have a very low solubility in water, and water has a very low
solubility in FlouroCarbons.
The greater number of Carbon atoms, the increased amount of
Boiling Point, density, viscosity etc. Except Gas solubility, all the
physical properties have a positive correlation with the number of
Carbons in FCs.
INDUSTRIES THAT RELY ON ALTERNATIVES
Air Conditioning Industry: millions of offices, public buildings,
hospitals, hotels, and apartment buildings depend on HFCs to meet
ambient temperature requirements.
Food: The importance of refrigeration to the food manufacture,
distribution and retail industries is fundamental: it plays a vital role in
ensuring that food reaches consumers both fresh and fit to eat.
Aerospace & Electronic Industries: Previously dependent upon CFCs
as solvents to achieve the very high levels of cleanliness required
ensuring safe and consistent operation; these industries are now
turning to HFCs and HCFCs. In fact, at present, they are often
technically, environmentally and economically the best solutions.
INDUSTRIES THAT RELY ON ALTERNATIVES
Insulation: Fluorocarbon-blown foams provide better
insulation than other blowing agents being proposed, such
as hydrocarbons or carbon dioxide. Used in different
applications, (e.g. building construction, refrigerated
transport, heating pipes) foams blown with fluorocarbons
conserve energy efficiently, providing environmental and
Medical: Due to their very low toxicity, a certain types of
HFCs are developed as propellants replacing CFCs in
metered dose inhalers (MDI) for asthmatics. Dry powder
inhalers are able to replace only a comparatively small
fraction of the widespread MDI applications.
"My findings do not agree with the climate models
that conventionally thought that greenhouse gases,
mainly CO2, are the major culprits for the global
warming seen in the late 20th century, Instead, the
observed data show that CFCs conspiring with cosmic
rays most likely caused both the Antarctic ozone hole
and global warming. These findings are totally
unexpected and striking, as I was focused on studying
the mechanism for the formation of the ozone hole,
rather than global warming.”- Qin- Bing Lu, professor
of physics and astronomy at the University of
CFCs are one of the first examples of man made chemicals contributing to
the global warming and depleting ozone layer phenomena
Through the collection of data, we were able to see that many “designer
chemicals” that have integrated themselves in society have moral, ethical,
social, economic and environmental implications, that should be continued
to be researched
Also, it is important to note when tackling such problems, the entire
international community must be involved in one global initiative to
decrease the use of CFCs, However differing economic, social and
environmental situation must be accounted for
It is necessary for the scientific community to monitor and research how
humanity‟s applications of science affect the sustainability of the earth
Aside from developing alternatives, political action and global mandates are
very effective in curbing the use of these chemicals, though are subject to
change as time progresses
Our study of CFCs has led to conclude that there are definitely
ways to curb human dependence on ozone depleting
chemicals, by researching as a team we looked into various
perspectives on this issue, and believe maintaining the earth‟s
sustainability will always be a collective effort regardless of
approach. The reduction of CFCs are regarded as a scientific as
well as political triumph, showing how taking responsibility as
global citizens is very important when pursuing scientific
endeavours. However, the impacts of CFCs will still be felt well
into the next century, and as we look to the future we must
heed the lessons of CFCs to find ways to lessen our
dependence on chemicals that harm the earth.
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