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In the 1970's scientist discovered that chemicals called chlorofluorocarbons, or CFC posed a threat to the precious ozone layer when used for extensive periods of time. CFC's have chemical and physical properties that make them valuable in industry. CFC's are and unreactive chemically.
"They are non-toxic, non-corrosive, non-flammable, and very stable."( ) .
And for these reasons they have been used in fire extinguishers, as propellants in aerosols, solvents in electronics manufactured, and as foaming agents in plastics.
"Notable among the physical properties of some CFC's are boiling point near room temperature, so they are readily liquefied under pressure. This makes them ideally suited for use as the coolant in refrigerators, and air conditioners." ( ) .
CFC's became a major part of early industry especially after the Second World War and thus they were widely distributed and used among almost everyone who owned a fridge, and used aerosol sprays. However, our ozone was thick and plentiful so the effects where not seen for sometime.
CFCs do not dissolve in rain and after several years it carried by the winds and eventually they reach the stratosphere without being modified.
"Here the molecules are broken down by the intense UV light, and free chlorine atoms are created by this degradation. Each chlorine atom can destroy several thousands of ozone molecules before being removed from the atmosphere: chlorine is a catalyst for the ozone depletion, and Bromine is even more effective than chlorine." ( ).
Hydrochlorofluorocarbons (HCFCs) were the new replacement for CFCs that they were less destructive to the Earth's atmosphere. Replacement compounds for CFCs have also been tested for their Ozone Depletion Potential (ODP). HCFCs still contain chlorine atoms, but the presence of hydrogen makes them reactive with chemical species in the troposphere. This greatly reduces the prospects of the chlorine reaching the stratosphere.
