Ozone layer depletion is one of the most serious problems faced by our planet earth. It is also one of the prime reasons which are leading to global warming. Ozone is a colourless gas which is found in the stratosphere of our upper atmosphere. The layer of ozone gas is what which protects us from the harmful ultraviolet radiations of the sun. The ozone layer absorbs these harmful radiations and thus prevents these rays from entering the earth’s atmosphere. Ozone is a tri atomic form of oxygen (O3), found in the Earth’s atmosphere. A combination of low temperatures, elevated chlorine, and bromine concentrations in the upper stratosphere are responsible for the destruction of ozone. The production and emission of chlorofluorocarbons (CFCs), is the leading cause of ozone layer depletion. CFC’s account for almost 80% of the total depletion of ozone. Ultraviolet radiations are high energy electromagnetic waves emitted by the sun which if enters the earth’s atmosphere can lead to various environmental issues including global warming, and also a number of health related issues for all living organisms. The fact that UV-B can cause biological effects is well demonstrated by the familiar sunburn that follows overexposure to the sun. However the health impacts of excessive exposure to UV-B go beyond just getting burned. Exposure to UV radiation has been linked to many human health problems, including skin cancer. Scientists also indicate that increased exposure to UV-B rays affects the human immune system and causes premature aging of the skin.
The ozone layer protects us from these harmful rays. The ozone layer acts as a natural filter, absorbing most of the sun’s burning ultraviolet (UV) rays. Stratospheric ozone depletion leads to an increase in UV-B that reach the earth’s surface, where it can disrupt biological processes and damage a number of materials. The process of absorption of harmful radiation occurs when ozone molecules split up into a molecule of oxygen, and an oxygen atom. The oxygen atom (O), recombines with the oxygen molecule (O2) to regenerate an ozone (O3) molecule. Thus, the total amount of ozone is maintained by this continuous process of destruction, and regeneration. This free chlorine atom reacts with an ozone molecule (O3), and forms chlorine monoxide (ClO), and a molecule of oxygen. Now ClO reacts with an ozone molecule to form a chlorine atom, and two molecules of oxygen. The free chlorine molecule again reacts with ozone to form chlorine monoxide. The process continues, and this results in the depletion of the ozone layer.Ozone is a colorless gas found in the upper atmosphere of the Earth. It is formed when oxygen molecules absorb ultraviolet photons, and undergo a chemical reaction known as photo dissociation or photolysis. It is important to note that UV-B radiation has always these effects on humans. In recent years these effects have become more prevalent because Canadians are spending more time in the sun and are exposing more of their skin in the process. An increase in the levels of UV-B reaching the Earth as a result of ozone depletion may compound the effects that sun worshipping habits have already created. The main things that lead to destruction of the ozone gas in the ozone layer. Low temperatures, increase in the level of chlorine and bromine gases in the upper stratosphere are some of the reasons that leads to ozone layer depletion. But the one and the most important reason for ozone layer depletion is the production and emission of chlorofluorocarbons (CFCs). This is what which leads to almost 80 percent of the total ozone layer depletion. In this process, a single molecule of oxygen breaks down into two oxygen atoms. The free oxygen atom (O), then combines with an oxygen molecule (O2), and forms a molecule of ozone (O3). The ozone molecules, in turn absorb ultraviolet rays between 310 to 200 nm (nanometers) wavelengths, and thereby prevent these harmful radiations from entering the Earth’s atmosphere.
There are many other substances that lead to ozone layer depletion such as hydro chlorofluorocarbons (HCFCs) and volatile organic compounds (VOCs). Such substances are found in vehicular emissions, by-products of industrial processes, aerosols and refrigerants. All these ozone depleting substances remain stable in the lower atmospheric region, but as they reach the stratosphere, they get exposed to the ultra violet rays. This leads to their breakdown and releasing of free chlorine atoms which reacts with the ozone gas, thus leading to the depletion of the ozone layer. Fair-skinned, fair-haired individuals are at highest risk for skin cancer, the risk for all skin types increases with exposure to UV-B radiation. The effects of UV-B on the human immune system have been observed in people with all types of skin. There are three main types of skin cancer, basal cell carcinoma, squamous cell carcinoma, and malignant melanoma. Most cases of skin cancer in Canada are either basal or squamous cell carcinoma. Basal and squamous cell carcinomas progress slowly and rarely cause death because they usually don’t spread to other parts of the body. These cancers are easily removed by surgery. Melanoma is the most serious and fortunately the least common form of skin cancer. Scientists strongly suspect that malignant melanoma, which can be fatal, is caused by exposure to UV light.
Ozone layer depletion is not something that affects any specific country or region. The whole world is vulnerable to its after effects. That makes it important for each and every one of us to take actions to reduce ozone layer depletion. International agreements such as Montreal protocol in 1987 have helped in reducing and controlling industrial emission of Chlofluorocarbons. More and more of such international agreements between countries is necessary to bring down ozone layer depletion. At individual level each and everyone also can contribute towards reducing ozone layer depletion. Buying and using recycled products, saving of energy, using of public transport can do a lot in combating ozone layer depletion. The most important thing that we can do is spreading awareness. Our individual efforts will go a long way in saving the earth’s blanket and keep our planet earth liveable for us and our future generations.
Impact on Humans
• Skin cancer: Exposure to ultraviolet rays poses an increased risk of developing several types of skin cancers, including malignant melanoma, and basal and squamous cell carcinoma.
• Eye damage: Direct exposure to UV radiations can result in photokeratitis (snow blindness), and cataracts.
Effects on the eyes
UV-B radiation can damage several parts of the eye, including the lens, the cornea, and the membrane covering the eye (conjunctiva). “Snow blindness” is the result of overexposure to UV-B and occurs in areas of the world with high levels of UVexposure, including snowy regions at high altitudes. Snow blindness is not unlike a sunburn, and if repeated, can cause damage to eye over the long term.
Cataracts are a clouding of the eye’s lens and are the leading cause of permanent blindness world wide. They are a result of overexposure to UV. A sustained 10% thinning of the ozone layer is expected to result in nearly two million new cases of cataracts per year globally.
• Immune system damage: Effects of UV rays include impairment of the immune system. Increased exposure to UV rays weakens the response of the immune system.
• Accelerated aging of skin: Constant exposure to UV radiation can cause photo allergy, which results in the outbreak of rashes in fair-skinned people.
• Other effects: Ozone chemicals can cause difficulty in breathing, chest pain, throat irritation, and hamper lung functioning.
Effects on the immune system
UV affects our ability to fight disease. The body’s immune system is its first line of defense against invading germs. Recent research has shown that some viruses can be activated by increased exposure to UV.
Effects on the environment
Ultraviolet radiation not only affects humans, but wildlife as well. Excessive UV-B inhibits the growth processes of almost all green plants. There is concern that ozone depletion may lead to a loss of plant species and reduce global food supply. Any change in the balance of plant species can have serious effects, since all life is interconnected. Plants form the basis of the food web, prevent soil erosion and water loss, and are the primary producers of oxygen and a primary sink (storage site) for carbon dioxide.