Cfc and ozone depletion pdf

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. 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. In addition to their nobel prize winning work showing that. The ozone depletion potential odp is the ratio of the impact on ozone of a chemical compared to the impact of a similar mass of chlorofluorocarbon cfc 11. Ozone hole in north america during 1984 abnormally warm, reducing ozone depletion and 1997 abnormally cold, resulting in increased seasonal depletion. Ozone in the troposhere has harmful effects on many living things because it is toxic. Chlorofluorocarbons ozone depletion occurs when the natural balance between the production and destruction of stratospheric ozone is disturbed. In history, the activities highlight the process of change connected with the use of refrigerants throughout history.

Column ozone is the total amount of ozone between the earths surface and space, or mathematically, it is the vertical integral of ozone concentration moleculescubic cm. When there was no ozone layer, life could only exist in. What emissions from human activities lead to ozone depletion. Global warming and ozone layer depletion will doubtless receive. The main effect of ozone depletion is an increase in uvb rays reaching the earths surface causes. Skeptics vs ozone hole lunar and planetary laboratory. It contains some videos and gif at thte end from an external source. Ozone depleting substances are the substances such as chlorofluorocarbons, halons, carbon tetrachloride, hydrofluorocarbons, etc. Cfcs and ozone depletion nature and community mother. In many countries, cfc use in aerosol cans is now prohibited. Two rogue scientists roland and molina appeared determined to find answers to suspected ozone depletion. Ozone depletion ozone depletion chlorofluorocarbon. This timeline highlights the average area of the ozone hole between september 7th and october th as observed by nasa spacedbased instruments see colored bars and scale. 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.

Effects of ozone depletion ozone depletion is affecting the human health and environment negatively, as it allows the penetration of uv radiations to reach the earth. Title vi for stratospheric ozone protection, signed into law. Chlorofluorocarbons cfcs, along with other chlorine, and brominecontaining compounds, have been implicated in the accelerated depletion of ozone in the earths stratosphere. This was finally enough to inspire real policy changes. Presentation on ozone depletion linkedin slideshare. If each chlorine atom released from a cfc molecule destroyed only one ozone molecule, cfcs would pose very little threat to the ozone layer. But in the stratosphere, the region of the atmosphere from 6 to 31 miles, ozone absorbs potentially damaging ultraviolet uv radiation. All of us are aware of how the concern related to depletion of ozone layer and the ozone hole, which also led to the ban of many chemicals such as the chlorofluorocarbon cfc. The ozone layer helps to protect life from harmful ultraviolet radiation. A cfc is any foreign corporation with more than 50 per cent of i the total combined voting power of all classes of its stock entitled to vote, or ii the total value of its stock is owned, directly or indirectly, or through certain related parties, by us shareholders on any day during the taxable year of the foreign corporation. 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. Cfcs break down the earths ozone layer, rowland and molina were key in convinc ing scientists. The mechanism of the ozone layer depleted by cfcs was identified.

Ozone levels were actually decreasing all over the planet. Ozone depletion facts and information national geographic. During the hearings, representative john doolittle, a california republican, stated, my own belief, is that the. These then react with the ozone molecules, resulting in their removal. Chlorofluorocarbons and ozone depletion american chemical. Instruments on the ground and on satellites, balloons, and aircraft. Ozone depletion is largely a result of manmade substances. The ozone layer protects living things from harmful ultraviolet rays from the sun. The ozone layer is a region of the stratosphere containing ozone, or o3 gas. Other gases that contribute in depletion of the ozone layer are nitric oxide no, nitrous oxide n2o, hydroxyl oh, atomic chlorine cl from chlorofluorocarbons cfcsand atomic bromine. 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.

Chlorofluorocarbons and ozone depletion answer guide. What is the role of chlorofluorocarbons in ozone depletion. The ozone hole stratospheric ozone protection and cfcs nh des. In 1985, the observation of an ozone hole in the antarctic pole provided proof that the ozone layer was depleting. Management of ozonedepleting substances reported to the. These emissions into the atmosphere ultimately lead to stratospheric ozone depletion.

Ozone was found to drop in the early spring of two of the coldest continentsthe arctic, and antarctica having the most seasonal depletion after ozone could be measured. Find out what caused the ozone hole, and how the 1989 montreal protocol sought to put an end to ozone depletion. The following table is reproduced from irc section 4682b. That stratospheric ozone absorbs ultraviolet radiation that otherwise. Greater ozone depletion in the polar regions caused these areas to warm some two and onehalf 2. Apr 18, 2019 the ozone layer helps to protect life from harmful ultraviolet radiation. The source gases that con tain only carbon, chlorine, and fluorine are. The ozone layer is about 300 to 500 du thick on average, which is about the thickness of two stacked pennies. Timeline of stratospheric ozone depletion and observations. If cfc production continued, however, ozone loss would be even greater. Cfcs were phased out via the montreal protocol due to their part in ozone depletion.

The chlorofluorocarbon and the halons are potent ozone depletors. Cfcs have a lifetime in the atmosphere of about 20 to 100 years, and consequently one free chlorine atom from a cfc molecule can do a lot of damage, destroying ozone molecules for a long time. Clo is a highly reactive gas that is involved in catalytic ozone destruction cycles throughout the stratosphere see q9. These radiations can cause severe diseases in humans such as skin cancer, eye damage and genetic mutations etc 9. Free chlorine cl atoms then react with ozone molecules, taking one oxygen atom to form chlorine monoxide clo and leaving an oxygen molecule o2. Ozone depleting chemicals odc excise tax audit techniques guide.

These chemicals are found in cleaning agents, aerosols, insulating foam, and refrigerants. Although natural phenomenon can cause ozone depletion but human activities such as cfcs are now accepted as major cause of depletion 9. Cfc and hcfc refrigerants also contribute to the depletion of the ozone layer when released into the atmosphere please refer to table on page 12 in this guide. Ozone depletion is affecting the human health and environment negatively, as it allows the penetration of uv radiations to reach the earth. Odp is a relative value of the ozone destructive potential of a chemical substance by unit weight emitted into atmosphere, with the unit weight of cfc 11 as 1. The ozone depletion factor reflects the potential ozone depletion that results from one kilogram of a given chemical compared to the ozone depletion that results from one kilogram of cfc 11 trichlorofluoromethane. Ozone depletion is a concern because stratospheric ozone is the primary agent responsible for limiting biologically damaging solar ultraviolet radiation. Nasa 34 the antarctic ozone hole is an area of the antarctic stratosphere in which the recent ozone levels have dropped to as low as 33 percent of their pre1975 values. This protocol produced a complete ban on the production of cfcs by 1995 with. The ozone layer is mainly found in the lower portion of the stratosphere, about 20 to 30 km 12 to 19 miles above the earth, though the thickness varies seasonally and geographically. Now our hairspray, refrigerators, and other products are cfc free. On the evaluation of ozone depletion potentials solomon. Depletion of o3 can increase uv radiation entering earth surface. Ozone layer can absorb over 99 % of the uv ray from solar radiation and thus protect the lives on earth from uv injury as a natural umbrella of earth.

It is quite clear that cfc s are not the controlling factor. Free chlorine atoms then break apart molecules of ozone, creating a hole in the ozone layer. Ozone layer depletion is one of the major environmental issues which is getting thinner day by day as a result of increasing pollution. Nearly 90% of earths ozone is in the stratosphere and referred to as the ozone layer. 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. Pdf cfc destruction of ozone major cause of recent global.

After taking that action, we pretty much forgot about ozone depletion and cfcs for 10 years. National aeronautics and the ozone hole space administratio n. Following is the list of some of the main ozone depleting substances and the sources from where they are released. The only way to control ozone thinning is to reduce the production of cfcs and nitrogen oxides. Just like the global warming scam, the ozone hole scam was another opportunity for government to tax and control, and another opportunity for scientists to imagine themselves saving the planet. They estimated that if cfc use was banned right away, ozone loss would go on for years. Chemicals called chlorofluorocarbons, or cfcs and other ozonedepleting substances are gradually destroying the ozone layer. The thinning is most pronounced in the polar regions, especially over antarctica. Ozonedepleting substances reported to tri many class i and class ii ozonedepleting substances are included on the tri chemical list, and hence, the quantities released to the environment or otherwise managed as waste are reportable to epas tri program. When there was no ozone layer, life could only exist in the sea. Ozone layer depletion is one of the major environmental issues which is getting thinner day by day as a. In 1990, governments from all over the world agreed to phase out cfcs. Defined in this manner, odp is a useful measure of the potential for each com.

Class i odss typically have an odp of greater than 0. Ozone and chlorine monoxide clo, for example, have been observed extensively with a variety of instruments. Chloroflourocarbons cfc are the big dog as far as causes of ozone depletion are concerned. Solomon and albritton, 1992 as a measure of the effectiveness of a given compound in removing ozone, relative to a standard compound, which is taken to be cfc 11. Our powerpoint presentation about ozone depletion, its effects and its causes. All ozone depleting chemicals contain chlorine and bromine 10. Achievements in stratospheric ozone protection epa. The main effect of ozone depletion is an increase in uvb rays reaching the earths surface. It consists of the ozone depletion potential odp for substance x with time horizon th and the effect factor ef for the. The ozone layer is reduced when manmade cfc molecules comprised of chlorine, fluorine, and carbon reach the stratosphere and are broken apart by shortwave energy from the sun. Apr 19, 2018 it is quite clear that cfc s are not the controlling factor. The ozone depletion issue caused governments to enter into treaties to reduce cfc emissions and private organizations to seek cfc alterna. Ozonedepleting substances ods generally contain chlorine, fluorine, bromine, carbon, and hydrogen in varying proportions and are often described by the general term halocarbons.

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 the earth and the effect of this on human health and on the environment. All that complacency vanished, however, after scientists discovered a large hole in the ozone layer. Causes of ozone layer depletion and its effects on human. Ozone depletion ends when reactive halogen gases are removed by rain and snow in the troposphere and deposited on earths surface. Ozone absorbs a band of ultraviolet radiation called uvb. Near the ground, ozone forming as a result of chemical reactions involving traffic pollution and sunlight may cause a number of respiratory problems, particularly for young children. 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. The concept of ozone depletion potential odp is widely used wuebbles et al. Hfcs, pfcs and sf6 are not ozone depleting substances, however, compared to co2, they have a. Ozone depletion atmospheric ozone layer depletion is a serious problem currently facing the world. Tthe ozone hole and global he ozone hole and global global. Ozone depletion free download as powerpoint presentation. Ozone absorbs uvb radiation, so its depletion allows more of this high energy radiation to reach the earths surface.

The chemical reaction caused by the cfc s and halons break down ozone molecules and thus, results in the reducing capacity of uv rays of the ozone layer. Mar 21, 2020 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 depletion is primarily caused by human activities. The cfc to hfa transition and its impact on pulmonary drug.

Ozone depletion by halogen source gases occurs glob ally. Large seasonal ozone losses occur in polar regions as a result of reactions involving polar stratospheric clouds pscs. The effect of cfcs 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. Stratospheric chlorinebromine loading depends upon the surface emissions of gases such as chlorofluorocarbons cfcs, hydrochlorofluorocarbons. Tthe ozone hole and global he ozone hole and global wwarming 1arming 1 the ozone hole and global warming global warming global warming is an increase in the average.

Jan 20, 2010 chloroflourocarbons cfc are the big dog as far as causes of ozone depletion are concerned. Cfc s are man made chemicals that are very stable in. Money and time are being spent on ozone repair, but the problem still exists. What are the causes and effects of ozone depletion.

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. The ozone layer protects humans, animals, and plants from harmful ultraviolet rays. Atmospheric composition diagram showing cfc transport. 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. Chlorofluorocarbons cfc s, carbon tetrachloride, and methyl chloroform are important humanproduced ozonedepleting gases that have been used in many. Although emissions of cfcs around the developed world have largely ceased due to international control agreements, the damage to the stratospheric ozone.

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