Cfcs Cause Deterioration of the Ozone LayerThe deterioration of the ozone layer , caused by Cfcs, endangers thelives of humans’. Cfcs have a diminishing effect on the ozone layer. Furthermore, the deterioration of the ozone cause an increase of Ultraviolet(UV) radiation which can have a negative effect on human skin and eyes. As awriter for newsweek, I have investigated the scenario and found the followinginformation. The earth’s atmosphere is a blanket of air that surrounds the planet.
This atmospheric air is made up of many different gases, 78% nitrogen, 21%oxygen, and 1% of a dozen or more other gases like carbon dioxide, helium, andozone. This atmosphere extends many miles out from the earth’s surface. However, this layer is not a uniform layer, from top to bottom. As one movesout from the planet’s surface the atmosphere becomes progressively dense. Thisatmosphere can be divide into four major regions. The first region is the troposphere which extends about 6.
5 miles abovethe planet’s surface. The troposphere contains the oxygen that we breath and iswhere a majority of our weather takes place. Beyond the troposphere is the second region of the atmosphere, thestratosphere. The stratosphere extends from roughly 6.
5-30 miles from theearth’s’ surface. The air on this region is much less dense than in thetroposphere, and it’s a lot drier. The stratosphere is the area that containsthe majority of the ozone layer. Past the stratosphere is the mesosphere which extends to 50 miles abovethe planet. The last region is the thermosphere. The thermosphere’s outermostedge is roughly 600 miles above the surface of the earth.
Beyond it, theairless vacuum of space begins. Oxygen is made up of two oxygen atoms that are bonded together. In theperiodic table it is represented by O2. Like oxygen, ozone is a gas that is made up of oxygen atoms. However,a molecule of ozone is made up of three atoms of oxygen bonded together,therefore, O3, represents ozone.
The ozone makes up only . 01% of the atmosphere. Furthermore, 90% of the ozone is found in the stratosphere. It is concentratedin a layer between 7 and 22 miles above the earth’s surface. The massive depth of the ozone in the stratosphere would lead you tobelieve that it is very thick, it is not.
If it were condensed, the ozonelayer would only be a few millimeters thick (Rowland and Molina 1994. p. 23). The ozone is made in the stratosphere.
It is continuously being formed,broken down, and reformed, over and over again. Furthermore, the three keyelements of the cycle are: oxygen, ozone, and the energy from the sun. The ultimate source of energy for our planet is the sun. This energytravels through space in the form of Electromagnetic Radiation. Furthermore,this electromagnetic radiation is often referred to as waves and their length,therefore, wavelengths. The sun has a wide range of wavelengths.
This range isknown as the Electromagnetic Spectrum. In this spectrum there is Gamma,Ultraviolet, Visible, Infrared, and Radio waves. It is the ultraviolet (UV) radiation coming from the sun that drives theozone cycle in the stratosphere. When a oxygen molecule is hit by a high-energyUV ray, the O2 molecule absorbs the ray’s energy.
As a result, the bond holdingthe oxygen molecule together breaks. This break separates the molecule, O2=O+O. These separate molecules quickly join with nearby oxygen molecules to form aozone molecule, O3=O2+O. Simultaneously, ozone molecules are being hit, theyabsorb the ray’s energy and break apart, leaving behind an oxygen molecule and asingle oxygen molecule, O3>O2-O. At this time, the entire process repeatsitself making new molecules that are separated which combine to make newmolecules, over and again (Rowland and Molin 1991 p. 42).
As a result of this cycle, about the same amount of ozone is produced asis broken down in the stratosphere. Therefore, the amount of ozone stays thesame under normal circumstances (Rowland and Molina 1991 p. 43). A constant and stable ozone layer are important for life on earthbecause the high-energy UV rays that are absorbed in the ozone layer areextremely dangerous. These rays can kill some things while seriously damagingothers. For example, some bacteria exposed to UV rays will die.
Plants, onland and in oceans, can be seriously damaged or even destroyed by UV rays. Whenhumans are exposed to the powerful rays, their skin can burn, damage to the eyes, and permanent changes in cells that can lead to cancer and other problems canoccur. By absorbing the UV rays, the ozone molecules in the ozone layer form ashield that protects life on earth from the dangerous and even deadly UV rays. Cfcs affect this process. Chloroflourocarbons (Cfcs) are man-made chemicals that were invented in1928.
However, they were not used on a large scale until the 1950’s. There aremany different types of Cfcs, but they all contain the same basic elements:chlorine, flourine, and carbon. Furthermore, different Cfcs contain differentamounts of these elements. Some of the more commonly used Cfcs are: Cfc 11,also known as R-11, Cfc 13, and Trichloroflouromethane; Cfc 12, also known asfreon, R-12, Cfc 12, and Dichlorodiflouromethane; and the third common type isCfc13, also known as R-113, CF2CICFC12, and 1,1,2 Trichlorotrifluroethane. Moreover, Cfcs are considered to be chemically unreactive, or stable. Due to their stability, Cfcs have been used for many different tasks.
For example, Cfc 12 is the most popular liquid coolants for refrigerators andair conditioners. Several other Cfcs work well as aerosol propellants, inmanufacturing foam, and in making Styrofoam containers. Furthermore, others arebeing used for cleaning delicate electronic equipment, such as computer chipsand circuit boards. Moreover, these Cfcs appeared to be the perfect industrialchemical because they were, seemingly, completely safe for people and theenvironment. However, two scientists, F.
Sherwood Rowland and J. Molina becamecurious if they were as stable high in the atmosphere as they were on earth. In1974 they published a paper which outlines their concerns and findings on Cfcs. In their paper, Rowland and Molina explain how Cfcs would damage theozone layer. After evaporation, due to their stability, Rowland and Molinareasoned, the Cfcs would not combine with other molecules in the air. Therefore,they wouldn’t be involved in the natural process that removes most foreignchemicals from the lower region of the atmosphere.
Instead, they would remainthere for a long period of time, “50-200 years”(Rowland 1991 p. 32), graduallyrising through the troposphere into the stratosphere(Rowland and Molina 1974p. 39). In the stratosphere, Cfcs would be exposed to UV radiation. Onceexposed to the UV radiation the bond that holds the chlorine containingcompounds together would be broken by the rays. When a molecule of a Cfc breaksapart, chlorine atoms (CL) are released.
Furthermore, individual chlorine atomsare very reactive. Rowland and Molina knew from laboratory experiments thatchlorine atoms react with ozone molecules on a way that destroys the ozone. Therefore, the two hypothesized that Cfcs would indeed harm the ozone layer inthe same way they affected Cfcs in experiments on earth. They warned society ofthe dangers, however, they were not taken seriously until the 1980s when Britishscientists, working at Halley Bay, using a Dobson spectrometer, discovered thewhole in the ozone layer over the Anartic coast(Farman, Gardiner, and Shaklin,p. 207). In 1985, the British scientists told the world about their findings,subsequently in 1995 Rowland and Molina were awarded the Nobel Peace prize.
Furthermore, currently scientists are certain of the damage done by Cfcs. However, Cfcs themselves do not destroy the ozone, their decay products do. After Cfcs reach the stratosphere and come into contactphotolyze withUV radiation, the chlorine atoms are released. Furthermore, due to their highreactivity, the chlorine does not remain single for very long, they rapidly joinnearby molecules. Since these reactions are occurring in the ozone layer, manyof these nearby molecules are ozone molecules. When a chlorine atom and a ozone molecule come together, the chlorineatom binds to one of the oxygen atoms on the ozone molecule.
“As a result ofthe reaction, the ozone molecule is destroyed and a molecule of oxygen andchlorine monoxide (CIO) are left over”(Rowland 1989 p. 71). The ozone-destroying process does not stop there. Each one of the CIOmolecules go on to react with other molecules nearby. When two CIO moleculescome together, they briefly combine. This molecule breaks apart very quickly,leaving oxygen gas (O2) and chlorine atoms (CL).
These chlorine atoms are nowfree again to destroy more ozone molecules. With the destruction of ozonemolecules, comes more destructive UV rays. The type of UV rays absorbed by the ozone layer are the same ones thatare most harmful to humans; skin cancer and cataracts. Furthermore, depletionof the ozone layer results in increased UV radiation exposure.
One affect of UV on humans is skin cancer. “Most skin cancers fall intothree classes: basal cell carcinomas, squamous cell carcinomas, and melanomas. In the US there were 500,000 cases of the first, 100,. 000 cases of the second,and 27,000 of the third type, in 1990″(Wayne p. 47).
Furthermore, cases ofmelanoma have been estimated to be increasing at an average of 10% from 1979 to1993 and even larger increases are believed to be occurring in the southernhemisphere. Also, studies suggest that a 1% decrease in stratospheric ozonewill result in a 2% increase of skin cancers (Wayne p. 49). Moreover, some ofthese skin cancers can result in death. Malignant melanoma is much moredangerous, however, they are the least common.
Malignant melanoma effects thepigment cell in the skin which can spread rapidly to the blood and lymphaticsystem. Furthermore, Wayne says, these have become increasingly frequentthroughout the world, especially in areas of higher latitudes. Moreover, “thereis a correlation between melanomas and exposure to UV. Melanoma incidence iscorrelated with latitude, with twice as many deaths (relative to statepopulation) in Florida or Texas as in Wisconsin or Montana”(Wayne p. 50). Furthermore, melanomas can take up too 20 years to develop, therefore, time willgive us a better example of the effects of increased UV rays have on the skin.
The eyes are also affected by UV rays. An increase in UV rays results in an increase of UV absorption by theeye. Chronic UV exposure has been shown to be a factor in eye disease, saysRoach. Moreover, “blindness from cataracts is the number one preventable causeof cataracts” (Roach p. 119). The latest findings indicate that “for every 1%decrease in ozone levels results in a .
6-. 8% increase in eye cataracts, orannually approximately 100,000 to 150,000 additional cases of cataract-inducedblindness worldwide” (Roach p. 122-3). Moreover, UV rays cause other eye injures including photokeratitis, alsoknown as sun blindness or snow blindness, damage to the retina, and intraocularmelanoma tumors. Roach’s predictions suggest a substantial future increase ineye cancer rates.
However, some, object to the effects Cfcs have on the ozoneand on humans. Two of the more common objections are: Cfcs are two heavy to reach thestratosphere and we should not be concerned about Cfcs because the majority ofchlorine in the atmosphere is created by the acidification if salt spray. However, for the first objection, atmospheric gases do not segregate byweight in the troposphere and the stratosphere. This is because verticaltransport in the troposphere takes place by convection and turbulent mixing,says Wayne. Furthermore Wayne says, in the stratosphere and in the mesosphere,it takes place by “eddy diffusion”, the gradual mechanical mixing of gas bymotions on smaller scales, these mechanisms due not distinguish molecularmasses (Wayne Ch.
4). As for the second objection, it is an assumption that is not correct atall. “Eighty percent of the chlorine found is from Cfcs and other man madeorganic chlorine compounds (Rowland 1989 p. 77). In conclusion, despite the increasing list of negative affects of UVradiation, we continue to release ozone depleting chemicals into the atmosphere. Despite the availability of safer alternatives, we continue to promotetechnologies that are only slightly safer than the ones they replaced.
Despiteall of the current information on the destructive affects of Cfcs, we stillcontinue to use them on a mass scale. Scientific research has only began to discover the impacts of UVradiation, however, what we do know should be enough for action. We cannotafford to sit around and wait for the damage to reach a point that makes usreact, by then it will be too late. The time to act is now because even with an immediate and complete endto production and release of ozone-depleting substances to the environment, weare still left with many decades of decreasing ozone and increased UV exposure.
We must think long term and act now. Works CitedFarman, J. C. , B. G.
Gardiner, and J. D. Shankin. “Large losses of total ozone inAntarticareveal seasonal CIOx/NOx interaction.
” Nature v. 230 (Aug. 4,1985): p. 205-215. Roach, M. “Sun Track.
” Health v. 201 (May/June 1992): p. 119-125. Rowland, F. S. “Chloroflourocarbons and the depletion of stratospheric ozone.
“American Scientist v. 128 (Nov. 4,1989): p. 70-78. Rowland, F.
S. and M. J. Molina.
“Ozone depletion: 20 years after the alarm. “ChemicalEngineering News v. 20 (Jan. 11,1994): p.
20-34. Rowland, F. S. and M. J.
Molina. “Chloroflourocarbons in the environment. “Rev. Geophys.
and Space Phys. v. 7 (Mar. 1975): p. 13-73Wayne, R.
P. Chemistry of Atmosphere. New York: Oxford Univ. ,1991.