What are the causes and effects of ozone depletion. The ozone depletion potential of n 2 o under current atmospheric conditions is computed to be 0. Apr 18, 2019 the ozone layer helps to protect life from harmful ultraviolet radiation. Ozone layer depletion is one of the major environmental issues which is getting thinner day by day as a. One of the main reasons for the widespread concern about depletion of the ozone layer is the anticipated increase in the amounts of ultraviolet radiation received at the surface of. Cfcs destroy the ozone in the stratosphere 15 20 km above the earths surface ozone concentrations are measure in dobsen units, 1 dobsen unit represents 1 molecule of o 3 for every 1 billion air molecules ozone loss is greatest over antarctica where the ozone depletion has been recorded and is commonly referred to as the ozone hole. Money and time are being spent on ozone repair, but the problem still exists. Although a combination of weather conditions and cfc chemistry conspire to create the thinnest ozone levels in the sky above the south pole. The ozone layer protects humans, animals, and plants from harmful ultraviolet rays. The ozone layer has historically protected the earth from the harmful uv rays, although in recent decades this protection has diminished due to stratospheric ozone depletion. Pdf causes of ozone layer depletion and its effects on. Ozone depletion potential is measured relative to cfc 11 and it represents the amount of ozone destroyed by emission of a vapor over its entire atmospheric lifetime relative to that caused by the emission of the same mass of cfc 11. It is found largely in the stratosphere that extends from about 6 km at the poles and 17 km at the equator to about 50 km above the earths surface.
One of the main reasons for the widespread concern about depletion of the ozone layer is the anticipated increase in the amounts of ultraviolet radiation received at. This guide is current through the publication date. Ozonedepleting substances ods generally contain chlorine, fluorine, bromine, carbon, and hydrogen in varying proportions and are often described by the general term halocarbons. Although natural phenomenon can cause ozone depletion but human activities such as cfcs are now accepted as major cause of depletion 9. Ozone depletion facts and information national geographic. The ozone hole stratospheric ozone protection and cfcs nh des. Cfc s are man made chemicals that are very stable in. Sep 30, 2019 the ozone layer has historically protected the earth from the harmful uv rays, although in recent decades this protection has diminished due to stratospheric ozone depletion.
Ozone holes are first discovered in antarctica in 1970. Ozone holes sources of cfcs, ozone depletion, effects of. The main cause of 0 3 layer depletion is the presence of chlorine containing gases primarily cfc s and related hydrocarbons due to the presence of uv light, these gases dissociate and release chlorine atom, which then leads to o 3 destruction. In addition, increased surface uv leads to increased tropospheric ozone, which is a health risk to humans. In 1978, the use of cfc propellants in spray cans was banned in the u.
Ozone depletion is primarily caused by human activities. In history, the activities highlight the process of change connected with the use of refrigerants throughout history. But through domestic and international action, the ozone layer is healing and should fully recover by about 2065. All ozone depleting chemicals contain chlorine and bromine 10. The world meteorological or ganization wmo, 1995 predicted that the depletion of the ozone layer peaked around 1998 and the layer would slowly recover by 2045 12. If cfc production continued, however, ozone loss would be even greater. Cfc replacements used as refrigerants, aerosol propellants. Cfcs break down the earths ozone layer, rowland and molina were key in convinc ing scientists. Ozone layer the ozone layer is basically naturally occurring gas in the region of stratosphere where ozone particles are accumulated 2. While in the case of atmospheric ozone depletion, in a situation of high uncertainty and against strong resistance, climate change regulation attempts at the international level such as the kyoto protocol have failed to reduce global emissions. As of 2010, the use of cfcs is extremely restricted in all 196 countries. Causes of ozone layer depletion and its effects on human. Ozone is bad in the troposphere because it is harmful to breathe and is the primary component. Due to depletion of ozone uv rays are penetrating in troposphere and leading.
Ozone depletion over india with so much worry about the rapid ozone depletion taking place in various parts of the earth, indian scientists are closely monitoring the ozone layer over india for possible depletion trends. Chlorofluorocarbons and ozone depletion american chemical. Hcfcs are less damaging to the ozone layer, generally with an odp of between 5% and 10% of the cfc potential. This website addresses stratospheric ozone issues, including the science of ozone depletion, epas regulatory approach to protecting the ozone layer, epaapproved alternatives to ozonedepleting substances, and sun safety. In the 1980s, the antarctic ozone hole appeared and an international science assessment more strongly linked the release of cfcs and ozone depletion. George wypych, in handbook of solvents third edition, 2019. The ozone layer helps to protect life from harmful ultraviolet radiation. Ozone layer depletion is one of the major environmental issues which is getting thinner day by day as a result of increasing pollution. Jan 20, 2010 chloroflourocarbons cfc are the big dog as far as causes of ozone depletion are concerned. Ozone layer is also naturally broken down but there is a balance between its formation and natu. The ozone depletion potential represents the amount of stratospheric ozone destroyed by the release of a unit mass of a chemical at earth. Ozone is a form of oxygen o3, most of the atmospheric ozone occurs in the stratosphere region, the greatest concentration of ozone occurs between 1930km. Feb 12, 2018 far above earths surface, the ozone layer helps to protect life from harmful ultraviolet radiation. Ozone depletion occurs during the long months of polar darkness over antarctica when the polar vortex isolates the air in the center.
The odp is the ratio of the impact on ozone of a chemical compared to the impact of a similar mass of cfc. Few years ago ozone holes are also discovered in arctic region. Use of hfcs in place of cfcs will go a long way in protecting our ozone layer from getting depleted. Chloroflourocarbons cfc are the big dog as far as causes of ozone depletion are concerned. These substances are effective ozonedepleters for two reasons. Uncovering the hidden hazard of hairspray a usual morning routine might include a spritz of hairspray, a spurt of shaving cream, or a spray of deodor. Stratospheric chlorinebromine loading depends upon the surface emissions of gases such as chlorofluorocarbons cfcs, hydrochlorofluorocarbons. Presentation on ozone depletion linkedin slideshare. Ozone in the troposhere has harmful effects on many living things because it is toxic. Scientists first began to realize the potential for chlorine to interact destructively with ozone in the early 1970s, and sherwood rowland and mario molina warned of the danger that cfcs posed to the ozone layer in 1974. Ozone depletion and climate change, or ozone hole and global warming in more popular terms, are environmental challenges whose connections have been explored and which have been compared and contrasted, for example in terms of global regulation, in various studies and books there is widespread scientific interest in better regulation of climate change, ozone depletion and air pollution, as. The molecules of chlorofluorocarbons in the stratosphere are broken down by the ultraviolet radiations and release chlorine atoms. Countries can control the import and manufacture of cfc product.
The natural concentration of ozone is maintained by the reversibility of o 3, and o 2, due to manmade materials, the abundance of chlorine monoxideich air in the stratosphere goes on changing its concentration, this chlorine monoxiderich with nascent. The chlorofluorocarbon and the halons are potent ozone depletors. It became evident that a stronger world wide response was needed. Ozone depletion, gradual thinning of earth s ozone layer in the upper atmosphere caused by the release of chemical compounds containing gaseous chlorine or bromine from industry and other human activities. Ozone layer depletion cause, effects, and solutions. Global warming and ozone layer depletion are two different problems see the sidebar misconceptions about global atmospheric change on page 95. Global warming is caused by the greenhouse effect, which is essential to life as we know it on planet earth. Montreal protocol banning the production of cfcs and halons. Ozone depletion potential odp c global warming potential gwp c halogen source gases chlorine gases cfc 11 45 5291 1 4750 cfc 12 100 4199 0.
When chlorine nitrate, a chemical that ties up chlorine in an ozonesafe form, was added to the hypothesis, the expected amount of ozone loss decreased. Ozone depletion would magnify all of the effects of uv on human health, both positive including production of vitamin d and negative including sunburn, skin cancer, and cataracts. However, the montreal protocol requires the complete phaseout of hcfcs globally by 2040. Cfcs used to be the largest contributor to ozone depletion. It is formed by the action of ultraviolet radiation on ordinary oxygen and is a gas, boiling point112 centigrade the cambridge paper back encyclopedia. Ozone depletion is the process of destruction of the ozone layer which can cause adverse effects on the living forms by many pollutants releases out from the vehicles, industries etc. Ozonedepleting substances ods contain various combinations of the chemical elements chlorine, fluorine, bromine, carbon, and hydrogen and are often described by the general term halocarbons. The first is that they are not reactive chemically speaking, which means they survive long enough in the atmosphere to drift up into the. This protocol produced a complete ban on the production of cfcs by 1995 with. Ozone depletion potential an overview sciencedirect topics. Thus, ozone layer depletion has become a major concern among the environmentalists. Odp values used in the montreal protocol table 1 example odp values substance odp value reporting value cfc 11 1 cfc 12 1 cfc 1 0. Ozone depletion is largely a result of manmade substances.
These chemicals are found in cleaning agents, aerosols, insulating foam, and refrigerants. Chlorofluorocarbons or the cfc are the main cause of ozone layer depletion. Since changes may have occurred after the publication date that would affect the accuracy of this document, no guarantees are made. Scientific assessment of ozone depletion, world meteorological organization a used as foam blowing agent or solvent b value was erroneously reported as 0. Ozone depleting chemicals odc excise tax audit techniques guide. Fire extinguishers contain halons and methyl bromide in the form of pesticides can also be also a cause for the depletion. Product information sorted by product type and name type product r number odp1 gwp2 cfc 12 1 high 10900 high 502 0,33 high 4657 high. Replacing cfc s used in air conditioners and refrigerators hydrofluorocarbons hfcs have been identified as potential replacements for cfcs which is the major cause of ozone layer depletion as they have an ozone depletion potential of 0. The sun renews the ozone and natural chemicals in our atmosphere destroy it. When chlorine nitrate, a chemical that ties up chlorine in an ozone safe form, was added to the hypothesis, the expected amount of ozone loss decreased. For each ods, this page provides the compounds atmospheric lifetime, ozone depletion potential ozone depletion potentiala number that refers to the amount of ozone depletion caused by a substance.
Ozone depletion atmospheric ozone layer depletion is a serious problem currently facing the world. Formation and depletion effect of the montreal protocol on stratospheric cl sunlight incident on earth is very roughly. Ozone is good in the stratosphere because it absorbs all of the most energetic ultraviolet radiation uvc, most of the uvb radiation and some of the least energetic uv radiation uva. That stratospheric ozone absorbs ultraviolet radiation that otherwise. Ozonedepleting substances ozone layer protection us epa. The main effect of ozone depletion is an increase in uvb rays reaching the earths surface causes.
This website addresses stratospheric ozone issues, including the science of ozone depletion, epas regulatory approach to protecting the ozone layer, epaapproved alternatives to ozone depleting substances, and sun safety. Cfc s are man made chemicals that are very stable in the atmosphere. There are exemptions to the imposition of the odc taxes under irc 4681, which includes the tax on odcs and on imported taxable chemicals. This danger is a direct consequence of the fact that cfcs which contain carbon, fluorine and chlorine are so inert. Chlorofluorocarbons cfc s, carbon tetrachloride, and methyl chloroform are important humanproduced ozonedepleting gases that have been used in many. Cfc s and ozone depletion key concepts ozone in the atmosphere ozone in the lower atmosphere troposphere about 10% of all ozone o 3 in the atmosphere is found in the troposhere up to 16km above the earths surface. Even the proponents of humaninduced ozone depletion are starting to realize that the thinning of the ozone layer is a natural phenomenon that just waxes and wanes. This is the cause for the nearly 80% of the ozone depletion. These are released by soaps, solvents, spray aerosols, refrigerators, airconditioners, etc.
With the release of each and every cfc, our ozone layer takes one small step towards its destruction. Ozone is a form of naturally occurring gas and 90% of our planets ozone is in the stratosphere. Rowland, a professor of chemistry at the university of california, irvine, and molina, a postdoctoral fellow in rowlands laboratory, had shown that chlorofluorocarbons cfcs could destroy ozone, a molecule made up of three oxygen atoms, o 3, in earths stratosphere. First global surface observations of cfcs reported. Far above earths surface, the ozone layer helps to protect life from harmful ultraviolet radiation. The atmosphere is mostly transparent to the visible except for scatter.
There are both links and major differences between ozone depletion and global warming and the way the two challenges have been handled. Learn what cfcs are, how they have contributed to the ozone hole, and how the 1989 montreal. Conclusion there is no doubt that the problem of ozone depletion exists and deserves extensive research and attention. The chlorine ion catalyzing o 3 depletion can take place in the gaseous phase, but it is dramatically. Since 2000 rate of ozone depletion is increasing 0. The chain reaction mentioned above takes about 40 years before the full effect is felt. Looking back over the scientific investigation of ozone depletion, we can see how the molinarowland hypothesis evolved with new data. The thinning is most pronounced in the polar regions, especially over antarctica. In addition to their nobel prize winning work showing that. Chlorofluorocarbons ozone depletion occurs when the natural balance between the production and destruction of stratospheric ozone is disturbed. Chlorofluorocarbons and ozone depletion answer guide.
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