Whats can destroy the ozone layer? (give diffrent answerz plzz)?

CFC Products-


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';CFC-free'; means specifically that the product does not contain or use chlorofluorocarbons and is therefore ';ozone safe.';





CFCs are listed as Class I (most harmful) stratospheric-ozone destroyers in Title VI of the United States Clean Air Act Amendments of 1990. Along with halons, carbon tetrachloride and 1,1,1-trichloroethane (methyl chloroform), these chlorine-based chemicals account for about 80 percent of ozone depletion.





CFCs have gotten the most publicity of all the ozone depletors. They are compounds comprised of carbon, fluorine, chlorine, and hydrogen. When CFCs were first developed in the 1930s by Du Pont, they were thought to be wonder chemicals because they were useful and nontoxic to humans. Only many decades later did we begin to learn how CFCs harm the environment.





By convection and diffusion, CFCs move upward through the atmosphere until they hit the ozone layer. When the reactive chlorine atoms of disintegrating CFCs collide with ozone (which is also unstable), a chlorine atom from the CFC steals an oxygen atom from the ozone molecule. Created in its place is a useless compound of one chlorine and one oxygen atom (chlorine monoxide) and a two-atom molecule of oxygen.





The oxygen atom of the chlorine monoxide molecule then starts searching for something to react with and bonds with the nearest oxygen atom, freeing the chlorine atom to find a new mate. By this constant change of dance partners, so to speak, a single chlorine atom can destroy 100,000 ozone molecules. Since this is happening a lot faster than Nature can replenish the ozone layer, sending a continuous stream of CFCs into our stratosphere is not a sustainable activity.





Twenty million tons of CFCs having who knows how many chlorine atoms have already been released into the air. Those released today won't reach the stratosphere for 10 to 15 years. If we completely stop using ozone-depleting chemicals today, it will still take until the end of the next century to heal the ozone layer.





Many products that have removed CFCs have replaced them with hydrochlorofluorocarbons (HCFCs or HFCs), a Class II chemical which causes less damage to the ozone layer, but still poses a threat. HCFCs have one-twentieth of the chlorine and more hydrogen, so they break down more easily in the atmosphere's lower levels. But organizations such as the Environmental Defense Fund and the Institute for Energy and Environmental Research oppose the use of HCFCs, saying that much of their chlorine still reaches the ozone layer.





Here in the United States, the manufacture and use of CFCs was prohibited for use in household aerosols in 1978, shortly after their ozone-depleting qualities were discovered. They are still allowed, however, in many other products. By enacting the Clean Air Act Amendments of 1990, the United States became the first nation to actually legislate the complete phase-out of CFCs.





There are no federal regulations regarding the use of buzzwords describing ozone safety, however, the Federal Trade Commission has stated that if a product makes an unqualified claim that it ';Contains no CFCs'; or is ';CFC-free,'; it should also not contain HCFCs, since these claims may imply to reasonable consumers that the product will not harm the ozone layer at all.





Since 15 May 1993, warning labels have been required by the EPA, in accordance with the 1990 Clean Air Act, on products that contain or are manufactured with Class I substances, including CFCs. Any product that uses CFCs must have a label conspicuously placed on the product that says it contains or is made with ';a substance that harms public health and environment by destroying ozone in the upper atmosphere.'; The EPA hopes that the warning labels will give manufacturers an incentive to make and sell products that do not use Class I ozone-depletors.





The EPA believes that substitutes can eventually be found for all products currently using Class I chemicals, and has imposed a ban on their production by the end of 1995 (they may still be present, however, in products manufactured prior to this date). Some will be replaced by the Class II HCFCs, but as soon as alternatives are available for HCFCs, there will be warning labels to discourage the use of these as well.





According to the United Nations Environment Programme, there has been a 40 percent drop in CFC consumption since 1986, a reduction beyond that required by the Clean Air Act and the Montreal Protocol. While this is an immense improvement, we still have a long way to go to get to zero ozone-depleting substances.Whats can destroy the ozone layer? (give diffrent answerz plzz)?
Human activity is by far the most prevalent and destructive source of ozone depletion, while threatening volcanic eruptions are less common. Human activity, such as the release of various compounds containing chlorine or bromine, accounts for approximately 75 to 85 percent of ozone damage.