Our Radiant Planet: Depletion of the Ozone Layer
Ozone is a relatively unstable form of molecular oxygen containing three oxygen atoms produced when upper-atmosphere oxygen molecules are split by ultra violet light. Stratospheric ozone is found in a broad band, extending generally from 15 to 35km above the earth. Although the ozone layer is surprisingly thin, it acts as a protective shield to the earth, as it filters out most of the harmful solar ultraviolet radiation (in particular UV-B) that would otherwise reach our planets surface.
Humans have damaged the ozone layer by adding molecules containing chlorine and/or bromine that lead to ozone destruction. The largest group among these are chloroflurocarbons (CFC's). At ground level, these molecules are very stable and have many uses in industrial and domestic applications, such as in spray cans, industrial solvents, degreasing compounds, and cooling in fridges. However when released into the stratosphere, such molecules can be broken down by energetic light rays (UV-C radiation) in a reaction that liberates an atom of chlorine, which destroys ozone by oxidising with the Ozone molecules, forming Cl-O and Oxygen. One atom of chlorine can destroy 10,000 ozone molecules! Atoms containing bromine, nitrous oxide, and hydrogen oxide radicals are also primarily dangerous. As a result, the Ozone in the stratosphere has been reduced to such an extent that ozone holes are appearing around the globe, in particular one over Antarctica that in 1995 measured 8.2 million square miles. This depletion has allowed more dangerous UV-B radiation to reach the earths surface.
So what effects will ozone depletion have on us? Although, at present, the ozone layer blocks out most of the damaging UVB radiation received from the Sun, a small amount slips by, damaging out skin in the form of sunburns and suntans. UVB radiation is strongly absorbed in the skin and in the outer layers of the eye. Human skin has developed various defence mechanisms against the damaging effects of UV radiation. The skin adapts to increased UV exposure by thickening its outer layer and by developing pigmentation that serves to shade the more vulnerable and deeper residing dividing cells. Overly damaged cells will normally self destruct through a process called apoptosis, and if this fails, the immune system should get rid of any resulting aberrant cells. It is when these natural safeguards fail or are overcome by UVB that real trouble can ensue. The most
The ozone layer is the one that protects living things from the pure ultraviolet rays of the sun.
15.2) The accumulation of chlorofluorocarbons is responsible for depleting the atmospheric zone. The atmospheric zone has changed in concentration due to human activity. The CFCs release chlorine atoms which react with ozone reducing it to molecular O₂. Following chemical reactions release the chlorine which reacts with other ozone molecules in a catalytic chain reaction. The ozone layer is getting thinner and thinner as stable air at places such as Antarctica allows reaction to continue. The accumulation of CFCs has led to increased UV radiation in sunlight reaching the earth thereby decreasing ozone levels. The global temperature has increased.
... Impact of ozone depletion on skin cancers. The Journal of Dermatologic Surgery and Oncology 14: 853-857.
”(Geduld) Although most of these deaths are from long term exposure to the pollutants there was still “2,682 deaths caused from short term exposure. ”(Geduld).“5.5 percent of cardiopulmonary (heart and lung disease related) deaths can be attributed to ground-level ozone exposure, which has increased over the past decade.” (David Suzuki Foundation) There were also “92’000 emergency-room visits and 620,000 visits to a doctor’s office in a year” It is estimated that by “2031 90,000 people will have died from short term exposure and 710,000 from long-term exposure to air pollution.
Scientists have performed many different tests and studies to learn more about high exposure to UV. Close observation of cells have shown that sunlight, natural or artificial, can cause mutations or DNA damage in cells. This can lead to further damage which will then be passed down through generations. Another study scientists perform is on animals. Scientist will expose your typical lab animals to UV rays, and this test typically results in skin cancer on the animal. These studies have been performed with UVA, UVB, and UVC, and they have all proven
When CFC molecules reach the stratosphere, the sun's radiation breaks it apart, freeing the chorine atom to destroy ozone molecules. The effect is a growing ozone hole which forms over Antarctica in October and usually lasts through mid November. During the annual ozone hole, the amount of UV radiation that reaches the Earth can double. Ozone depletion serves as a major health risk for human beings. The three primary health effects of ultraviolet radiation on human health are damage to the skin,eyes, and immune system.
The ozone layer shields the Earth and its inhabitants from the sun’s harmful ultraviolet rays. It absorbs or blocks out 95% of high frequency ultraviolet radiation. The layer is comprised of a molecule called ozone, an electrically charged form of oxygen that is produced when sunlight reacts with chemicals in the air. The ozone molecules have the ability to filter the radiation, allowing only a small fraction of it to pass through (Gribbon 56). The layer is found in the Earth’s stratosphere, with its peak concentration about twenty-five kilometres above the Earth’s surface.
The depletion of the ozone layer has been a trending topic after it was first discovered in 1970. The ozone layer is a portion of the earth’s stratosphere which absorbs most of the sun’s UV rays hence preventing cancer and other fatal illness to the skin. It contains high concentrations of O3 and at a constant rate is being broken down and. Since 1970, it has been discovered that about 4% of the ozone layer wears off every decade and is as a result of day-to-day human activity.
* Nitrogen Oxides are presented through the atmosphere. N2O are very powerful in the chemistry of the troposphere and the stratosphere, and they are very important in ozone production and in the destruction processes. There are a number of sources (the oxidation of N2O like lightning and fossil fuel combustion) whose contribution to NOx concentrations in the upper troposphere is not well measured.
Thus CFCs became used all over the world and its business got bigger and bigger until late in 1973. Sherwood Rowland and Mario Molina, two distinguished chemists, came up with a surprising result in his calculations concerning the CFCs and ozone layer. CFCs are basically inactive in the troposphere(around the altitude of 50,000 feet) so it would gradually drift upward until they reached the mid-stratosphere.(about 100,000 feet) At this point CFCs would be broken down by short-wavelength ultraviolet radiation from the sun. This radiation is the one which would not reach the lower atmosphere in large amounts because of the ozone layer. When these CFCs do brake down, they released atomic chlorine which then would react with the ozone and convert it back into plain oxygen. The even worse part of all this is that these chlorine molecules do not become inactive after the first reaction with the ozone and would be available to destroy more ozone molecules. Thus this process would be the function of a catalyst; a single chlorine atom involved in a chain reaction to destroy many ozone molecules.
Air pollution and greenhouse gases are the reason for the planet as it is today; the reason why we see campaigns flooding the media informing us to ‘switch off’, ‘save the planet’ and ‘turn down the heat’ and the reason why the government is trying to develop a successful scheme, such as the carbon tax scheme, to reduce air pollution caused by major industries. Air pollution and greenhouse gases are the two immediate causes of global warming and climate change. Air pollution occurs when chemicals or particulate matter enter the atmosphere. They can cause damage to living organisms on the planet, as well as destruction to the natural and synthetic environment (Energy Environment.net 2008). Greenhouse gases are gases in the atmosphere that absorb infrared radiation emitted from the earth. They trap infrared radiation in the form of heat, and hence contribute to global warming. Anthropogenic greenhouse gases are a direct result of air pollution. They are the physical gases emitted that cause air pollution. Naturally occurring greenhouse gases also have an influence on the earth’s atmosphere, though it is not as conspicuous as anthropogenic causes. Together, air pollution and greenhouse gases are intensifying climate change and global warming on a world-wide basis.
The basic set of reactions that involve this process are: Cl + O3 -->ClO + O2 and ClO + O -->Cl + O2 The net result: O3 + O -->2O2 Chlorine is initially removed in the first equation by the reaction with ozone to form chlorine monoxide. Then it is regenerated through the reaction with monatomic oxygen in the second equation. The net result of the two reactions is the depletion of ozone and atomic oxygen.6 Chlorofluorocarbons (CFCs), halons, and methyl bromide are a few of the ozone depletion substances (ODS) that break down ozone under intense ultraviolet light.
Our planet earth is surrounded by a blanket of gases called atmosphere that sticks to the ground due to gravity. It is made of various gases, among them ozone is a vital one. Ozone is the form of oxygen, each molecule of which
The amount of water that is on earth at any one time remains fairly constant because the water is moving form one reservoir into another such as river to ocean or ocean to atmosphere. This cycle involves the exchange of energy causes a change in temperature. This is why when evaporation occurs, it takes energy from its surroundings and cools the environment. While condensation occurs energy is released and the surrounding environment becomes warmer. The atmosphere is a mixture of nitrogen, oxygen, and other gasses that surround the earth. The atmosphere is made up of five layers known as the troposphere, the stratosphere, the mesosphere, the thermosphere, and the exosphere. The troposphere is the lowest layer of the earth’s atmosphere; it is also where all weather on earth takes place. The stratosphere is the second layer of the atmosphere, right above the troposphere. Above the stratosphere is the mesosphere and above that is the troposphere. The uppermost region of earth’s atmosphere is the exosphere. The air in the exosphere is extremely thin and almost the same as space. One of the many reasons the earths atmosphere is important is because it blocks
The atmosphere is an open system that consists of a gaseous mixture enveloping a planet (Answers.com). These gasses, known as air, include O2, N2 and H2O. The atmosphere is also composed of water, ice and dust particles. Atmosphere functions like a blanket, keeping Earth's heat from escaping into space (Lenkeit). It has also been compared to a greenhouse: like glass it lets short wave insulation inside, but keeps most of long wave ground radiation from going out (Lenkeit).