CFCs, which stands for chlorofluorocarbon, also known as Freon, are a family of colourless, odourless, organic gas compounds that were manufactured to be used mainly as coolants in refrigerators and spray can propellants. The main groups of CFCs are CFC-11, CFC-12, CFC-113, CFC-114 and CFC-115. CFCs are made of carbon, chlorine and fluorine atoms. The main type of CFC that is used more often is trichlorofluoromethane (CCI3F). CFCs are unreactive and stable. CFCs are classified as halocarbons: compounds made of carbon and halogen atoms. They are non-toxic and non-flammable. They are also greenhouse gases as they trap heat in the atmosphere when they are released by human activity. CFCs were first manufactured in 1928 to replace the dangerous substances that were being used. Before CFCs were made, refrigerators used ammonia (NH3), methyl chloride (CH2CL), sulfur dioxide (SO2) as refrigerants in the late 1800s and early 1900s. CFCs came into existence because of many fatal accidents that occurred in the 1920s; for example, methyl chloride leaked out of refrigerators. Three American corporations – Frigidaire, General Motors and Du Pont – started to search for a less toxic alternative. CFCs were used as refrigerants, in spray can propellants, air conditioners, solvents in cleaners -typically for electronic circuit boards- and they were also used in the production of foam, such as fire extinguishers. Their usage grew over the years.
The ozone layer is a layer in the stratosphere, which is 10-40 km above the Earth’s surface. Ozone consists of three oxygen atoms bonded together. It is a highly reactive molecule. The ozone layer is a protective layer of gas that absorbs intense ultraviolet radiation from the sun. Too much UV radiation is harmful for life and can penetrate skin and cause severe damage to organisms. Ozone is measured in Dobson units: a unit of measurement used to calculate the number of molecules between the earth’s surface and space. One Dobson unit is equal one layer of pure ozone which is around the value of 0.01 millimeter at 0ºC. An undamaged ozone layer has a value of 300 Dobson units. Small amounts of chlorine exist naturally in the atmosphere. CFCs rise into the stratosphere therefore, chlorine atoms enter the stratosphere. CFCs can stay in the atmosphere for approximately 100 years and eventually spreads throughout the ozone layer globally. Ultraviolet radiation breaks down CFCs and separates the chlorine. CFCs can potentially obliterate large amounts of ozone; the chlorine atom then bonds with one of the oxygen atoms that was once bonded with two other atoms to create ozone. This obliteration has been observed over Antarctica. The hole in the ozone layer increases ultraviolet radiation on the Earth’s surface. According to the Earth System Research Laboratory, per 1 chlorine atom, 100,000 ozone atoms are obliterated.