Running Head: OZONE DEPLETION

Taylor Graham

Ozone Depletion

The Ozone Layer
The ozone layer prevents most harmful solar ultraviolet light, (UV) from passing through the earth’s atmosphere by absorbing 93-99% of these UV rays. UV rays are potentially damaging to life on earth. The ozone layer is comprised of high concentrations of ozone, (03) and mainly located in the lower portion of the stratosphere (rabbitair.com). The atmosphere of the Earth is divided into 5 layers. From closest and thickest to farthest and thinnest the layers are: troposphere, stratosphere, mesosphere, thermosphere and exosphere. The majority of the atmosphere’s ozone resides in the stratosphere, which extends from 6 miles above the Earth’s surface to 31 miles (Sivasakthivel, 2011). The density of the ozone varies according to the season and also the location. The ozone layer has historically protected the Earth from the harmful UV rays, however in recent decades this protection has diminished due to stratospheric ozone depletion.
History of Ozone Depletion Ozone depletion is largely a result of man-made substances. Humans have introduced gases and chemicals into the atmosphere that have rapidly depleted the ozone layer in the last century. The possibility of ozone depletion was first introduced by scientists in the late 1960's as dreams of supersonic transport began to become a reality. Scientists had long been aware that nitric oxide (NO) can catalytically react with ozone (O3) to produce O2 molecules; however, NO molecules produced at ground level have a half-life far too short to make it into the stratosphere (Sivasakthivel, 2011). It was not until the advent of commercial supersonic jets (which fly in the stratosphere and at an altitude much higher than conventional jets) that the potential for NO to react with stratospheric ozone became a possibility. The threat of ozone depletion from commercial supersonic transport was so great that it is often cited as the main reason why the US federal government pulled support for its development in 1971 (Solomon, 1999). Fear of ozone depletion was abated until 1974 when Sherwood Rowland and Mario Molina discovered that chlorofluorocarbons could be photolysis by high energy photons in the stratosphere. They discovered that this process could release chlorine radicals that would catalytically react with O3 and destroy the molecule. This process is called the Rowland-Molina theory of O3 depletion.
From 1985 to 1988, researchers studying atmospheric properties over the South Pole kept noticing significantly reduced concentrations of ozone directly over the continent of Antarctica. For three years it was assumed that the ozone data was incorrect and was due to some type of instrument malfunction. In 1988, researchers finally realized their error and concluded that an enormous hole in the ozone layer had indeed developed over Antarctica (Solomon, 1999). Examination of NASA satellite data later showed that the hole had begun to develop in the mid 1970's.
The ozone hole over Antarctica is formed by a slew of unique atmospheric conditions over the continent that combines to create an ideal environment for ozone destruction. Because Antarctica is surrounded by water, winds over the continent blow in a unique clockwise direction creating a so called "polar vortex" that effectively contains a single static air mass over the continent. As a result, air over Antarctica does not mix with air in the rest of the earth's atmosphere.
Antarctica has the coldest winter temperatures on earth, often reaching -110 F. These chilling temperatures result in the formation of polar stratospheric clouds (PSC's) which are a conglomeration of frozen H2O and HNO3. Due to their extremely cold temperatures, PSC's form an electrostatic attraction with CFC molecules as well as other halogenated compounds. As spring comes to Antarctica, the PSC's melt in the stratosphere and release all of the halogenated compounds that were previously absorbed to the cloud. In the Antarctic summer, high energy photons are able to photolyze the halogenated compounds, freeing halogen radicals that then catalytically destroy O3. Because Antarctica is constantly surrounded by a polar vortex, radical halogens are not able to be diluted over the entire globe. The ozone hole develops as result of this process.
Recent research suggests that the strength of the polar vortex from any given year is directly correlated to the size of the ozone hole. In years with a strong polar vortex, the ozone hole is seen to expand in diameter, whereas in years with a weaker polar vortex, the ozone hole is noted to shrink. Effects of Ozone Depletion Ozone depletion affects every living organism in our ecosystem. It causes disruption in the marine life. Microscopic organisms known as phytoplankton are also affected by UV rays. Phytoplankton is the foundation of the food chain. If they die; other marine life that depends on them, will not survive. Studies have been conducted that show the damage that UVB has on marine life during the early developmental stages of fish, shrimp, and crab. The most severe effects are a decreased reproductive capacity as well as impaired larval development. An increase in exposure to UVB rays can cause a significant reduction in the marine population for animals which feed on these small animals. This causes a domino reaction in the ocean as well as humans who consume these foods.
Ozone depletion also affects plants. Several of the world's major crop species are particularly vulnerable to increased UV, resulting in reduced growth, photosynthesis and flowering. These species includes; wheat, rice, barley, oats, corn, soybeans, peas, tomatoes, cucumbers, cauliflower, broccoli and carrots/ A number of economically important species of plants, such as rice, depends on cyanobacteria residing on their roots for them to absorb and utilize nitrogen properly. Cyanobacteria are sensitive to UV light and they would be affected by its increase. Plant growth will also be affected by the increase in UV rays. Physiological and developmental processes of plants are affected by UVB radiation, despite mechanisms to reduce or repair these effects and a limited ability to adapt to increased levels of UVB.
The depletion of ozone makes humans more vulnerable to the UV-B rays which are known to cause skin cancer as well as other genetic deformities. In addition, UVB rays have been linked to cataracts, a clouding of the lens of the eye. Studies have also shown an increased exposure to UB-V rays on humans could damage the immune system, resulting in increased infectious diseases (Tevini, 1993).
The list of infectious diseases influenced by UV-B exposure continues to grow. UV-B irradiation of rodents has been shown to increase the lethality of both malaria and influenza virus infections as well as the severity of neurological symptoms following infection with herpes simplex virus (rabbitair.com). Ozone depletion and climate change may interact to enhance the spread and or severity of a number of diseases. In principle, changes in climate due to global warming could lead to alterations in the distribution of insects and other vectors that carry human and animal pathogens. Such alterations, combined with increased UV-B-induced immunosuppressant from ozone depletion, could increase the prevalence or severity of the diseases these pathogens induce. However, medical evidence is presently lacking to prove that such interactions do influence these diseases in places large and small populated by humans.
It has long been known for many years that exposure to UV can suppress the effectiveness of immunization in humans; recent work now shows that, even after successful immunization, UV can still suppress these immune responses (rabbitair.com) In earlier studies, suppression was only demonstrated in individuals who were first exposed to UV and then immunized. Now it has been reported that UV irradiation to simulated sunlight of already immunized individuals can also suppress the immune response. As a consequence, such individuals could become susceptible to re-infection.
People with lung diseases, such as asthma, chronic bronchitis, and emphysema will generally experience more serious health effects at lower ozone levels. Unfortunately children are at higher risk from ozone exposure because: they often play outdoors in summer when ozone levels are higher, they are more likely to have asthma, which may be aggravated by ozone exposure and their lungs are still developing (rabbitair.com). Breathing ozone can trigger a variety of health problems including chest pain, coughing, throat irritation, and congestion. It can worsen bronchitis, emphysema, and asthma. "Bad" ozone also can reduce lung function and inflame the linings of the lungs. Repeated exposure may permanently scar lung tissue. Healthy people also experience difficulty breathing when exposed to ozone pollution. Because ozone forms in hot weather, anyone who spends time outdoors in the summer may be affected, particularly children, outdoor workers and people exercising. Millions of Americans live in areas where the national ozone health standards are exceeded. Also many older adults may be more affected by ozone exposure, possibly because they are more likely to have pre-existing lung disease. Active people of all ages who exercise or work vigorously outdoors have higher exposure to ozone than people who are less active. Some healthy people are more sensitive to ozone (rabbitair.com). They may experience health effects at lower ozone levels than the average person even though they have none of the risk factors mentioned above.
Breathing ozone can trigger a variety of health problems including chest pain, coughing, throat irritation, and congestion. It can worsen bronchitis, emphysema, and asthma. "Bad" ozone also can reduce lung function and inflame the linings of the lungs. Repeated exposure may permanently scar lung tissue (rabbitair.com). Healthy people also experience difficulty breathing when exposed to ozone pollution. Because ozone forms in hot weather, anyone who spends time outdoors in the summer may be affected, particularly children, outdoor workers and people exercising. Millions of people throughout the world live in areas where the national ozone health standards are exceeded; thus, they are experiencing mysterious illnesses at an alarming rate.
The EPA has designated ozone one of six major pollutants reaping havoc on earth affecting humans, species and all habitats; therefore, it has become classified as a pollutant that must be kept in check at times by all means necessary. Yet few state governments have enforced regulations designed to bring ozone air pollution under control. Troposphere ozone levels in the more polluted regions of the Northern Hemisphere appear to be rising at about 1 percent per year (rabbitair.com). The American Lung Association reports that scientists' estimates of the annual number of deaths in the United States associated with air pollution range from 50,000 to 100,000. While another form of air pollution, particulate matter, is the one most prominently linked to premature death, ozone pollution plays an important role as well in this threat to human health continuously. It is very important that humans start considering other options in their daily habits of discarding waste in order to reduce harm to themselves and the planet.

What Can Be Done The good news is that in recent years, there have been signs that the ozone layer is being recovered. The Montreal Protocol was established by the international community in 1987 to protect the ozone layer. The European Union established policies that go beyond the requirements of the Montreal Protocol. As a result, the European Union had reduced its consumption of the main ozone depleting substances to zero by 2010. The European Union also banned the use of a toxic chemical called methyl bromide. The European Union’s legislation has been effective in controlling ozone depleting substances but also called for new technologies which provided alternatives for many of the harmful substances. These efforts have resulted in ozone depleting substances being reduced by 98%. (European Commission, 2012). Although signs are indicating that the ozone layer is recovering, there is still work to be done to maintain and continue this recovery. The following are recommendations of the Montreal Protocol and the European Union in order to continue the recovery of the ozone layer: Ensure that the existing restrictions on ODS are properly implemented and worldwide use of ODS continues to be reduced; ensure that ODS are replaced with climate-friendly alternatives; recover ODS from existing equipment and buildings; prevent illegal trade in ODS; and educe use of ODS in applications that are not considered as consumption under the Montreal Protocol.
These are things that have been done at the government level however there are things that each of us can do that will make a collective difference in maintaining the ozone layer. Some of the things will require more than time, others may require a monetary investment, however over time, monetary investments will yield returns on energy cost. The following are some suggestions: replace a regular incandescent light bulb with a compact fluorescent light bulb (CFL); install a programmable thermostat; move your thermostat down 2° in winter and up 2° in summer; clean or replace filters on your furnace and air conditioner; choose energy efficient appliances when making new purchases; do not leave appliances on standby; take a shower instead of a bath (a shower takes up to four times less energy than a bath. To maximize the energy saving, avoid power showers and use low-flow showerheads, which are cheap and provide the same comfort); and use the washing machine or dishwasher only when they are full. Ozone layer depletion is a key concern of many citizens around the world. The ozone layer is important in protecting the earth from the effects of UV-B rays. Humans have created pollutants that have caused harm to the ozone layer, but have also made substantial changes to correct the damage that has been done to the ozone layer. As a result, the ozone layer has recovered and continues to protect our environment. We aim to persuade everyone to take steps in their personal lives that will collectively lead to a healthier future for all species and our earth.
We also aim to raise awareness of the measures to prevent further depletion of the ozone layer at a personal level.

References
Rabbitair (n.d). Retrieved from http://www.rabbitair.com
Sivasakthivel, T. & Kumar,R. (2011). Health effects of ozone layer depletion. International journal of environmental science development, 2(1), doi: ijesd2011d500
Solomon, S. (1999). Stratospheric ozone depletion: A review. Reviews of geophysics, 275-316.
The importance of a healthy ozone layer. (September, 2012 12). Retrieved from http://ec.europa.eu/clima ozone/index_en.htm /policies/