Ozone layer depletion is defined as the breaking down of ozone molecules in the ozone layer by man-made chemicals, leading to increased amounts of ultraviolet light reaching earth’s surface and harming humans, animals, and plants. An ozone molecule consists of three oxygen molecules and is created when UV light breaks down an oxygen molecule, leaving it free to bind with other oxygen molecules. Ozone molecules play a big part in our atmosphere by blocking dangerous ultraviolet rays from reaching earth’s surface in the ozone layer. The actual ozone layer is located in the stratosphere, which is above the troposphere and below the mesosphere. The overall problem with the ozone layer is that humans were using too many chemicals and substances in machines and technology that would end up in the stratosphere breaking down many ozone molecules. This would lower the chance and capability of ozone molecules to block the dangerous ultraviolet rays released by the sun. Although many of the harmful chemicals that originally were used in different products were legal many years ago, they have been banned from daily use today by the Montreal Protocol and other laws and regulations. Though these laws help protect the ozone layer, the ozone depleting chemicals have already done their damage. A good example of the damage done by ozone depleting substances can be seen in the ozone hole over the Antarctic region. This hole has stretched over the whole continent and even out into some of the surrounding ocean. Thanks to the laws and regulations put in place, the hole has gotten smaller over the past few years. According to scientists, the ozone layer will not fully recover for at least another 50 years.
Why should you be concerned about this? This affects you because if exposed to ultraviolet rays too long, many problems and illnesses can result. Over exposure to UV rays can result in diseases like skin cancer, cataracts, sun burns, and problems with the immune system. To help fix the problem, governments and agencies have passed rules and laws like the Montreal Protocol to help cut down on the harmful substances and chemicals used. These rules have proved to help the ozone layer substantially so far, but there is still more work to be done. There are still many substances and products used daily that hurt the ozone layer. A good example of one could be nitrous oxide (N2O). This compound is commonly used medically as a “laughing gas”/anesthesia, but in racing and in rockets it is used as a propellant that speeds up the vehicle. This molecule has been proven to deplete the ozone layer, yet it is still used by people every day. Not only has this substance been proved to harm the ozone layer, but it also is a contributor to global warming because of its ability to trap heat by speeding up reactions between atoms and compounds. It is substances like these that will keep weakening the ozone layer if we do not do anything to control them.
Tuesday, May 25, 2010
Case Studies
The Effect Ultraviolet Light Has On Life Forms
-Ultraviolet light is given off by the sun and is usually blocked about 97% of the time by the ozone layer. In the past 20 to 30 years, the ozone layer has weakened resulting in more and more UV rays reaching the earth’s surface. This means more animals, plants, and humans will be negatively harmed. In humans and some animals, too much exposure to ultraviolet light can lead to injuries in the eyes, skin, and immune system. Diseases like skin cancer, cataracts, and sun burns can occur in humans from taking in too much UV light. In plants, too much UV light can lead to less crop production and can even kill certain plants. To prevent too much UV light form making it all the way to earth’s surface, we need to protect the ozone layer to block the harmful rays.
Case Studies
Ozone Depleting Substances
-The term ozone depleting substance is given to any substance the government identifies that depletes the ozone layer. Before the Montreal Protocol was passed in the early 1990’s, the substances now known as ozone depleting substances were used in everyday life and no one knew how harmful they really were. Some of these substances were commonly found in household equipment like refrigerators and air conditioners. After scientists discovered how harmful these chemicals really were, they passed the Montreal Protocol, which banned these chemicals and substances from daily use. Although most ozone depleting substances are not used anymore, there are still more out there that harm the ozone layer. An example of a harmful chemical could be nitrous oxide (N2O). Not only does this compound have a damaging affect on the ozone layer, this substance is also bad for global warming
Case Studies
The Ozone Hole Over Antarctica
-The ozone hole located over Antarctica is the biggest ozone “hole” on the planet. Since the weather is cold, there are a lot of human-made chemicals present in the atmosphere, and because of the areas of high and low pressure the Antarctic region provides a perfect place for an ozone hole to grow and thrive during the winter months. There have been some steps taken to help the ozone hole though. In the early 1990’s, some nations agreed on the Montreal Protocol, which bans some ozone depleting substances from everyday use, but there are still chemicals and substances present that deplete the ozone layer which should also be banned. Thanks to the work of governmental agencies like the EPA and other organizations, scientists predict the ozone hole to recover in the next 50 years.
Article Summaries
Title: New Culprit Seen in Ozone Depletion
Author: Cornelia Dean
Date Published: August 27, 2009
Source: New York Times
Web Link: http://www.nytimes.com/2009/08/28/science/earth/28nox.html?_r=1&scp=1&sq=ozone%20layer%20depletion&st=cse
Summary: In this article, it talks about how nitrous oxide is an underestimated molecule that ruins the ozone layer. In years past, chemicals like CFC’s were the main causes for ozone depletion, but now that they have been banned from everyday use by the Montreal Protocol, it is becoming clearer that other chemicals also deplete the ozone layer. Nitrous oxide is currently under inspection from the EPA to see if it should be banned from use because of its capability to “trap heat”, which plays a big part in worsening global warming.
Title: Bring Back The Ozone Layer!
Author: Sharon Begley and Mary Hager
Date Published: November 4, 1991
Source: Newsweek
Web Link: http://www.newsweek.com/id/127275
Summary: In this article regarding the phase out of ozone depleting substances, it talks about over 93 countries banning ozone reducing chemicals from the years 1990-2000. Although the phase out was supposed to help the ozone layer, scientists also found that the damage had already been done to the ozone layer and the scientists “have no idea of how bad it could get”. The article also states that because of the weakening ozone layer, the rates of skin cancer has doubled since 1980 and it might possibly get even worse. With the ozone layer getting even worse each year, the time period for recovery gets longer and longer. Already, scientists do not predict the ozone layer to recover until the middle of the 21st century. Even though the depleting ozone layer means more and more UV rays reaching earth, scientists say that since there will not be as many ozone molecules absorbing the UV rays in the stratosphere, it will keep the planet cooler and will help out with global warming. Scientists also say that the earth should be warmer than it currently is because of all the carbon dioxide and other heat-trapping gases that have been used and/or given off in the past 100 years by humans in places like power plants and in cars.
Title: Why is there an ozone hole in the atmosphere, whereas there is too much ozone at ground level? Why doesn't ground level ozone rise to fill the hole in the stratosphere? Why does the ozone up high stay there, and not sink to the ground?
Author: Ross J. Salawitch
Date Published: April 9, 2007
Source: Scientific American
Web Link: http://www.scientificamerican.com/article.cfm?id=experts-ozone-hole-in-atmosphere-not-on-ground
Summary: In this article, Mr. Salawitch talks about how ozone in the troposphere, or the lowest part of the atmosphere, has been given the name “bad ozone” while ozone in the stratosphere is called “good ozone” because of how it blocks ultraviolet radiation given off by the sun. The article also goes on to mention how ozone is naturally produced and destroyed, but the ozone layer is currently “leaking” from all the industrial pollutants that deplete it and help let UV radiation into the troposphere. The amount of ozone in the ozone layer is measured by Dobson units and there can be anywhere around 400 DU’s in the stratosphere on average. CFC’s play a big role in ozone depletion too. After being given off from household items like refrigerators and air conditioners, they will get up into the ozone layer and turn the ozone molecules back into oxygen molecules.
Title: Ozone Hole is Back and Big
Author: Amanda Onion
Date Published: Sep 06, 2001
Source: ABC News
Web Link: http://abcnews.go.com/Technology/story?id=98280&page=1
Summary: Amanda Onion reminds her readers in this article that the ozone hole in the Antarctic region in coming back to reach record size in the year 2001. This region is a perfect place for a huge hole in the ozone layer because of its cold temperatures, the large amounts of man made gases present in the air, and the areas of high and low pressure. Not only is there a hole over Antarctica, but above Chile there is also a growing hole. Scientists at NASA advised Chileans in September of 2000 to protect and shelter themselves from the growing ozone hole above the country. Although the Antarctic hole has reached record sizes in 2000 and 2001, Scientists think that it will disappear around 2040.
Title: Report: Antarctic Ozone Hole as Big as It's Ever Been
Author: Associated Press
Date Published: October 3, 2006
Source: Fox News
Web Link: http://www.foxnews.com/story/0,2933,217498,00.html
Summary: According to Fox News, in 2006 the ozone hole has reached a record setting size. Scientists at NASA were claiming that in 2006 there was the least amount of ozone particles in the ozone layer since 2000, which was another year that the hole was at a record high size. The ultraviolet radiation that will reach earth’s surface because of the ozone hole will harm both humans and animals at the bottom of the food chain. According to the scientist’s studies, the ozone hole seems to enlarge and thrive in the Antarctic winter months, especially September. Scientists at NASA also predict that the hole will not close and the ozone layer will not completely improve and recover until 2065, which is 15 years longer than they previously predicted.
Author: Cornelia Dean
Date Published: August 27, 2009
Source: New York Times
Web Link: http://www.nytimes.com/2009/08/28/science/earth/28nox.html?_r=1&scp=1&sq=ozone%20layer%20depletion&st=cse
Summary: In this article, it talks about how nitrous oxide is an underestimated molecule that ruins the ozone layer. In years past, chemicals like CFC’s were the main causes for ozone depletion, but now that they have been banned from everyday use by the Montreal Protocol, it is becoming clearer that other chemicals also deplete the ozone layer. Nitrous oxide is currently under inspection from the EPA to see if it should be banned from use because of its capability to “trap heat”, which plays a big part in worsening global warming.
Title: Bring Back The Ozone Layer!
Author: Sharon Begley and Mary Hager
Date Published: November 4, 1991
Source: Newsweek
Web Link: http://www.newsweek.com/id/127275
Summary: In this article regarding the phase out of ozone depleting substances, it talks about over 93 countries banning ozone reducing chemicals from the years 1990-2000. Although the phase out was supposed to help the ozone layer, scientists also found that the damage had already been done to the ozone layer and the scientists “have no idea of how bad it could get”. The article also states that because of the weakening ozone layer, the rates of skin cancer has doubled since 1980 and it might possibly get even worse. With the ozone layer getting even worse each year, the time period for recovery gets longer and longer. Already, scientists do not predict the ozone layer to recover until the middle of the 21st century. Even though the depleting ozone layer means more and more UV rays reaching earth, scientists say that since there will not be as many ozone molecules absorbing the UV rays in the stratosphere, it will keep the planet cooler and will help out with global warming. Scientists also say that the earth should be warmer than it currently is because of all the carbon dioxide and other heat-trapping gases that have been used and/or given off in the past 100 years by humans in places like power plants and in cars.
Title: Why is there an ozone hole in the atmosphere, whereas there is too much ozone at ground level? Why doesn't ground level ozone rise to fill the hole in the stratosphere? Why does the ozone up high stay there, and not sink to the ground?
Author: Ross J. Salawitch
Date Published: April 9, 2007
Source: Scientific American
Web Link: http://www.scientificamerican.com/article.cfm?id=experts-ozone-hole-in-atmosphere-not-on-ground
Summary: In this article, Mr. Salawitch talks about how ozone in the troposphere, or the lowest part of the atmosphere, has been given the name “bad ozone” while ozone in the stratosphere is called “good ozone” because of how it blocks ultraviolet radiation given off by the sun. The article also goes on to mention how ozone is naturally produced and destroyed, but the ozone layer is currently “leaking” from all the industrial pollutants that deplete it and help let UV radiation into the troposphere. The amount of ozone in the ozone layer is measured by Dobson units and there can be anywhere around 400 DU’s in the stratosphere on average. CFC’s play a big role in ozone depletion too. After being given off from household items like refrigerators and air conditioners, they will get up into the ozone layer and turn the ozone molecules back into oxygen molecules.
Title: Ozone Hole is Back and Big
Author: Amanda Onion
Date Published: Sep 06, 2001
Source: ABC News
Web Link: http://abcnews.go.com/Technology/story?id=98280&page=1
Summary: Amanda Onion reminds her readers in this article that the ozone hole in the Antarctic region in coming back to reach record size in the year 2001. This region is a perfect place for a huge hole in the ozone layer because of its cold temperatures, the large amounts of man made gases present in the air, and the areas of high and low pressure. Not only is there a hole over Antarctica, but above Chile there is also a growing hole. Scientists at NASA advised Chileans in September of 2000 to protect and shelter themselves from the growing ozone hole above the country. Although the Antarctic hole has reached record sizes in 2000 and 2001, Scientists think that it will disappear around 2040.
Title: Report: Antarctic Ozone Hole as Big as It's Ever Been
Author: Associated Press
Date Published: October 3, 2006
Source: Fox News
Web Link: http://www.foxnews.com/story/0,2933,217498,00.html
Summary: According to Fox News, in 2006 the ozone hole has reached a record setting size. Scientists at NASA were claiming that in 2006 there was the least amount of ozone particles in the ozone layer since 2000, which was another year that the hole was at a record high size. The ultraviolet radiation that will reach earth’s surface because of the ozone hole will harm both humans and animals at the bottom of the food chain. According to the scientist’s studies, the ozone hole seems to enlarge and thrive in the Antarctic winter months, especially September. Scientists at NASA also predict that the hole will not close and the ozone layer will not completely improve and recover until 2065, which is 15 years longer than they previously predicted.
Sunday, May 16, 2010
The Science Behind The Ozone Layer
-An Ozone molecule, which is also called trioxygen (O3), consists of three oxygen atoms and comes in the form of a bent molecule (similar to a water molecule). Ozone is made from the reaction of ultraviolet radiation from the sun and oxygen in the stratosphere. To start the reaction, UV radiation breaks apart a diatomic oxygen molecule. After the two oxygen atoms are separated apart, they go and bond with other O2 molecules to create a new ozone molecule (O2). The reaction is shown below:
O2 + (solar energy/ UV Radiation) → O + O2 → O3
-Ozone has a boiling point of -112 ° C, a melting point of −192.5 °C, and is considered a less stable allotrope of the diatomic O2. According to the the U.S. Environmental Protection Agency, a single atom of chlorine can destroy more than a hundred thousand ozone molecules. Along with chlorine, bromine, nitrogen, hydrogen, and oxygen gases also destroy ozone molecules. Ozone is considered to be a dangerous chemical and air pollutant when found in the lower atmosphere (below the stratosphere) because of the many negative effects it has on plants and animals. In animals, it can damage the respiratory system and also has many of the same effects it has on humans while in plants, it burns and kills the plant's cells.
-The ozone layer is found in the stratosphere, which is above the troposphere (the lowest region of the atmosphere) from 15-30 kilometers above sea level. About 90% of all of the worlds ozone can be found in the stratosphere. The ozone layer's main job is to prevent as much ultraviolet radiation from entering the troposphere and lower atmosphere as possible. The ozone layer blocks anywhere from 97-99% of the utlaviolet light given off from the sun In recent years past, we have used products that only deplete and reduce the amount of ozone in the ozone layer. Since there is not as much ozone to block the UV rays, more and more UV rays are entering the lower atmosphere and are harming humans. The artic circle is where the ozone layer is most depleted. The cold temperatures there speed up the breaking down of ozone molecules when certain chemicals come into contact with the ozone. In the winter of 1999-2000, the ozone layer over the artic circle lost over 60% of its ozone and is currently rebuilding, but scientists say that it will take decades for the ozone layer to rebound there. One chemical that has been used a lot that harms the ozone layer is dichlorodifluoromethane (CFC-12), which consists on chlorine, flourine, carbon atoms and otherwise known as freon-12. This chemical has been a significant part of most air conditioners, refrigerators, and aerosol spray products. Although it was a significant component of most of the products listed above, it has been banned more than ten years ago by the environmental protection agency and is not used any more. Along with banning CFC-12, the epa has also banned many other substance that they claim and have classified as ozone depleting substances.
O2 + (solar energy/ UV Radiation) → O + O2 → O3
-Ozone has a boiling point of -112 ° C, a melting point of −192.5 °C, and is considered a less stable allotrope of the diatomic O2. According to the the U.S. Environmental Protection Agency, a single atom of chlorine can destroy more than a hundred thousand ozone molecules. Along with chlorine, bromine, nitrogen, hydrogen, and oxygen gases also destroy ozone molecules. Ozone is considered to be a dangerous chemical and air pollutant when found in the lower atmosphere (below the stratosphere) because of the many negative effects it has on plants and animals. In animals, it can damage the respiratory system and also has many of the same effects it has on humans while in plants, it burns and kills the plant's cells.
-The ozone layer is found in the stratosphere, which is above the troposphere (the lowest region of the atmosphere) from 15-30 kilometers above sea level. About 90% of all of the worlds ozone can be found in the stratosphere. The ozone layer's main job is to prevent as much ultraviolet radiation from entering the troposphere and lower atmosphere as possible. The ozone layer blocks anywhere from 97-99% of the utlaviolet light given off from the sun In recent years past, we have used products that only deplete and reduce the amount of ozone in the ozone layer. Since there is not as much ozone to block the UV rays, more and more UV rays are entering the lower atmosphere and are harming humans. The artic circle is where the ozone layer is most depleted. The cold temperatures there speed up the breaking down of ozone molecules when certain chemicals come into contact with the ozone. In the winter of 1999-2000, the ozone layer over the artic circle lost over 60% of its ozone and is currently rebuilding, but scientists say that it will take decades for the ozone layer to rebound there. One chemical that has been used a lot that harms the ozone layer is dichlorodifluoromethane (CFC-12), which consists on chlorine, flourine, carbon atoms and otherwise known as freon-12. This chemical has been a significant part of most air conditioners, refrigerators, and aerosol spray products. Although it was a significant component of most of the products listed above, it has been banned more than ten years ago by the environmental protection agency and is not used any more. Along with banning CFC-12, the epa has also banned many other substance that they claim and have classified as ozone depleting substances.
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