The Ozone layer is destroyed by the Chlorofluorocarbons or CFCs, which were previously used in refrigerants and cleaning agents, and other Ozone Depleting Substances or ODS that, are used in fire extinguishers. The chlorine in the CFCs is released when the Ultraviolet light splits them and these halogen atoms destroy the Ozone by combining with the third Oxygen atom in the Ozone molecule. Subsequently, this molecule combines with a free Oxygen atom to release the halogen atom which again breaks up another Ozone molecule. One halogen atom destroys around a hundred thousand Ozone molecules (Fahey, 2003).
The main halogens that cause the depletion of the Ozone Layer are Chlorine and Bromine. Due to exposure to sunlight the halogen source gases are converted into halogen gases that are highly reactive. For instance, chlorine based gases get transformed to ClO or chlorine monoxide and bromine based compounds change to BrO or bromine oxide. In addition, chlorine and bromine atoms are also formed which are highly reactive and cause untold damage to the Ozone Layer (Fahey, 2003). The depletion of the Ozone Layer is not uniform and there is considerable variation with latitude.
Due to the extremely high Ozone losses in the Antarctic region the loss is at a global maximum there. The next highest losses transpire in the Northern Hemisphere. The air that has been depleted of Ozone spreads from the Polar Regions. The depletion in the tropical regions is the least because of the fact that reactive halogen gases are present in very small quantities (Fahey, 2003). Further, a seasonal variation has also been noticed in this Ozone Layer depletion process. In the Southern Hemisphere, there is not much of a variation in the process and the amount of depletion is around six percent.
However, in the Northern Hemisphere, the variation between winter and summer is from four percent to two percent respectively (Fahey, 2003). Atmospheric Ozone is of three forms the good form, the bad form and the natural form. Good Ozone is the Stratospheric Ozone that protects humans, animals and plants from UV B radiation. Bad Ozone occurs near the surface of the Earth due to chemical reactions and human activities that produce polluting gases. Industrial activity and the consumption of fossil based fuels cause an increase in bad Ozone (Fahey, 2003).
The natural form of Ozone is one of the constituents of a clean atmosphere and if there had been no human activities on the surface of the Earth then Ozone would have been observed at the surface of the Earth and in the troposphere and stratosphere. Ozone extracts other naturally and manmade gases in the atmosphere (Fahey, 2003). Realizing the gravity of the situation, twenty countries became signatories at Vienna to a treaty agreement in 1985. This treaty was named the Convention for the Protection of the Ozone Layer and it was decided to protect the Ozone Layer from the depredations of human activities.
Subsequently, the Montreal Protocol on Substances that Deplete the Ozone Layer was ratified in 1989 (Fahey, 2003). This Protocol implemented controls on the developed and developing countries in respect of the manufacture and utilization of chemicals that were instrumental in causing a depletion of the Ozone Layer. These measures were further strengthened by the 1990 London Amendments to the Protocol, which made it mandatory to reduce the production and consumption of such substances. The directives of the Montreal Protocol have proved to be successful to some extent.
With increasing depletion of the Ozone Layer the Ultra Violet Radiation reaching the surface of the Earth increases (Fahey, 2003). UV B radiation causes non melanoma skin cancer. In the United States of America skin cancer cases are increasing tremendously. The situation is very serious with twenty percent of the residents developing skin cancer. The fatalities from this disease alone are one per hour in the US (Health Effects of Overexposure to the Sun, 2006). Moreover, UVB causes actinic keratoses and premature aging of the skin.
Keratoses or lesions occur on the face, upper limbs and neck of individuals. These can lead to squamous cell carcinoma. In addition, UVB brings about a loss in the transparency in the eye lens or what is commonly termed as cataract. Millions of Americans are afflicted by this malaise every year and the expenditure this incurs is of the order of several billion dollars. Further, such radiation causes the degeneration of the macula or that part of the retina where visual perception is at its best.
Another grave problem created by such radiation is the impairment of the immune system of the human body (Health Effects of Overexposure to the Sun, 2006). The government of the state of Mississippi being seized with this extremely serious problem posed by UVB radiation has implemented several measures. In this state a large number of air-conditioning and refrigerating units are employed. Some of these refrigerants are Freon 12, Freon 22 and R 12. By 1995, the production of R 12 was completely stopped and new substances like HFC 134A are being used in its place.
The government has prohibited the release of Freon into the atmosphere and Freon is being sold only to certified technicians. All air conditioning and refrigerant equipment has to be thoroughly inspected in order to ensure that the leakage of Freon into the atmosphere is minimized (Moore & Kimbrough, 2007). A team of scientists, led by Dr. Yang, of the Georgia Institute of Technology, analyzed data collected over a quarter century. This data had been collected by NASA and NOAA or the National Oceanic and Atmospheric Administration.
Since, 1979 there had been a drastic depletion of the Ozone Layer. However, in 1997 a reversal in this trend was observed. This was in no small measure due to the proper implementation of the Montreal Protocol. This had prompted Yang and his team to conclude, after extrapolating from the available data, that the Ozone Layer would be restored to its 1980 status by the year 2050 (NASA, NOAA Data Indicate Ozone Layer is Recovering, 2006). However, till such time, it is imperative for people to take abundant precautions.
Some of these are the avoidance of the midday sun in summer, protecting the eyes from direct sunlight by wearing sunglasses that filter out Ultra Violet Radiation and eschewing the use of aerosols and CFCs. In addition, liberal use of sunscreen with a sun protection factor or SPF of 15 or more, protective clothing and wide brimmed hats have to be utilized, especially in the case of children. This is due to the fact that the skin of children is much more sensitive than that of adults. Moreover, every effort should be made to avoid direct sunlight, especially between 10 am to 4 pm.