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CFC's and the Depletion of the Ozone Layer
By: Danny Chin
Chlorofluorocarbon Background
Chlorofluorocarbons (CFC) are molecules made of carbon, fluorine, and chlorine atoms and are the main cause of ozone depletion in the stratosphere. Created in 1928 by Thomas Midgley Jr. and Charles Franklin Kettling, these molecules were given the trade name Freon. CFCs were long thought to be “miracle substances” because they are stable, nonflammable, nontoxic, and cheap. However, it has been shown that CFCs are “volatile derivatives of methane and ethane” that destroy ozone (Welch). CFCs are mainly used as coolants in refrigerators, and as solvents in cleaners, fire extinguishers, and foam-blowing agents.Once the CFCs enter the atmosphere, the wind carries these molecules to the stratosphere. Due to their stability, only exposure to intense ultraviolet (UV) lights can break the CFCs apart. However, when these molecules break apart the released chlorine destroys ozone ("Ozone Science: The Facts"). CFCs can remain in the atmosphere for 40 to 150 years and are deleterious in the ozone layer. After World War II, a plethora of CFC substances had been released into the air and no one had any idea where they went. By 1987, measurements confirmed that chlorine was the main cause in the decrease of ozone proving that CFCs were the main reason for ozone depletion ("The Science Checklist Applied"). The ozone layer of the upper atmosphere is very important because they protect us from the sun’s harmful UV rays by having the ozones absorb these harmful rays.
Ozone Depletion by CFC
The most common chemical formula for chlorofluorocarbon is CFCl3 and when this molecule interacts with UV rays from the sun, the carbon-chlorine bond breaks. Then, the chlorine bonds with the ozone by breaking the ozone molecule (O3) to create oxygen gas (O2) and chlorine monoxide (ClO), thus destroying the ozone. Free oxygen atoms break apart the chlorine monoxide, allowing the released chlorine atom to bond with and destroy more
ozone by absorbing the sun’s harmful UV rays (Singer). The chemical equation for this process is CFCl3 + UV Light ==> CFCl2 + Cl then Cl + O3 ==> ClO + O2 then ClO + O ==> Cl + O2 (How Ozone Is Destroyed). Because of this continuous reaction, a single CFC molecule can destroy 100,000 ozone molecules (How Ozone Is Destroyed). Ozone used to be naturally created and destroyed at a continuous pace, which created an equilibrium but after the discovery of CFCs ozone is now depleted faster than it is created which creates areas with less ozone such as the hole in Antarctica. Scientists measure the thickness of the ozone layer by measuring how much ultraviolet radiation reaches the ground by using a Dobson ozone spectrophotometer. Ozone layer thickness is measured in Dobson units which means the higher the number the thicker the ozone layer (“How Ozone Is Destroyed”). Ozone levels have fallen between 5-10% above the United States. According to the US Environmental Protection Agency (EPA), “..large fires and certain types of marine life produce one stable form of chlorine that does reach the stratosphere. However, numerous experiments have shown that CFCs and other widely-used chemicals produce roughly 84% of the chlorine in the stratosphere, while natural sources contribute only 16%”. Volcanic eruptions indirectly affect the ozone layer because they produce aerosols that increase chlorine’s effectiveness at destroying ozone ("Ozone Science: The Facts").
CFC Effects
Chlorofluorocarbon has many effects that range from cancerous cells in humans to the melting of ice caps in the north and south poles. CFCs affect the earth because when the amount of ozone in the Stratosphere decreases, the earth reacts to this change in unnatural and unusual ways. Studies have shown that the decrease in ozone allows harmful UVB bands to penetrate the ozone layer. The UVB causes nonmelanoma skin cancer and plays a major role in malignant melanoma development (Singer). UVB rays destructive properties also contribute to cataracts. CFCs also affect crops because the harmful rays from the sun destroy them. Destroyed crops mean a lesser supply of food for people. UVB has also been linked to the cause of certain material destruction such as plastic. UVB rays also penetrates water, causing marine life such as algae, coral, fish larvae and eggs, plankton, and other marine life to be affected by the harmful UV rays negatively. These are all organisms from the bottom of the food chain and less organisms on the bottom of the food chain means less food for the organisms higher up on the food chain causing other marine life to be affected and the food web to be disrupted. The CFC affected and affects the world so immensely that many countries gathered to resolve this major crisis.
The World’s Reaction to CFC
Many countries have tried and are trying in numerous ways to reduce and ban chlorofluorocarbon products. Chemist Mario Molina went on a campaign to end the use of CFCs in 1974. Molina gathered enough evidence to convince and inspire other scientists to check and expand his work. Because of Molina’s work, twenty-four countries immediately banned CFCs and her work also encouraged an expansion of ozone measurements worldwide and the development of more sophisticated instruments to measure ozone and other chemicals. This furthered the capability to study how the CFCs were exactly affecting the earth and led scientists to discover how the ozone was being consumed ("The Science Checklist Applied"). The 1987 Montreal Protocol on Substances that Deplete the Ozone Layer (Montreal Protocol Act) was ratified by the United States and 196 other countries in order to come together to protect the ozone layer by phasing out the production of numerous substances believed to be responsible for ozone depletion. With the alliances of all these countries to protect the environment and reduce the exhaustion of ozone in the stratosphere, the ozone layer is expected to recover by 2050 ("The Montreal Protocol on Substances"). The Clean Air Act (CAA) is a federal law in the United States to control air pollution. Also, scientists are creating new, safer, ozone-friendly molecules to replace the dangerous CFCs, such as hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs), both of which are less stable and have shorter lifetimes in the atmosphere (Welch). Although the world is on a good track toward repairing the ozone layer, the world’s citizens should also make an effort towards repairing the ozone layer to make a positive difference.
How Can We Help Reduce CFC Usage?
CFC usage can be limited by people in many ways. This will help countries achieve their goal to recover the ozone layer by 2050. People can help by buying CFC-free house products, such as cleaning products free of chlorofluorocarbon. People can also help by buying refrigerators that are CFC-free. Also, deodorant spray and other types of spray containing CFC should be limited and air conditioning should be used minimally.