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Saturday, March 20, 2010

banned substances

  The Montreal Protocol on Substances that Deplete the Ozone Layer is one of the first international environmental agreements that includes trade sanctions to achieve the stated goals of a treaty.  It also offers major incentives for non-signatory nations to sign the agreement.  The treaty negotiators justified the sanctions because depletion of the ozone layer is an environmental problem most effectively addressed on the global level.  Furthermore, without the trade sanctions, there would be economic incentives for non-signatories to increase production, damaging the competitiveness of the industries in the signatory nations as well as decreasing the search for less damaging CFC alternatives.    2.        Description       Man-made chlorines, primarily chloroflourobcarbons (CFCs), contribute to the thinning of the ozone layer and allow larger quantities of harmful ultraviolet rays to reach the earth.  The U.S. Environmental Protection Agency (EPA) has estimated that by the year 2075, the increased ultraviolet rays could result in over 150 million new cases of skin cancer in the U.S. alone, with the consequence of 3 million deaths.  Other damage caused by ultraviolet rays includes increased eye cataracts, and a


list of banned and restricted substances

Ozone depletion

From Wikipedia, the free encyclopedia

Image of the largest Antarctic ozone hole ever recorded (September 2006).

Ozone depletion refers to the slow, steady decline of about 4 percent per decade in the total volume ofozone in Earth's stratosphere (the ozone layer) since the late 1970s, and a much larger, but seasonal, decrease in stratospheric ozone over Earth's polar regions during the same period. The latter phenomenon is commonly referred to as the ozone hole. In addition to this well-known stratospheric ozone depletion, there are also tropospheric ozone depletion events, which occur near the surface in polar regions during spring.

The detailed mechanism by which the polar ozone holes form is different from that for the mid-latitude thinning, but the most important process in both trends is catalytic destruction of ozone by atomic chlorine and bromine.[1] The main source of these halogen atoms in the stratosphere isphotodissociation of chlorofluorocarbon (CFC) compounds, commonly called freons, and ofbromofluorocarbon compounds known as halons. These compounds are transported into the stratosphere after being emitted at the surface.[2] Both ozone depletion mechanisms strengthened as emissions of CFCs and halons increased.

CFCs and other contributory substances are commonly referred to as ozone-depleting substances(ODS). Since the ozone layer prevents most harmful UVB wavelengths (270–315 nm) of ultraviolet light (UV light) from passing through theEarth's atmosphere, observed and projected decreases in ozone have generated worldwide concern leading to adoption of the Montreal Protocolthat bans the production of CFCs and halons as well as related ozone depleting chemicals such as carbon tetrachloride and trichloroethane. It is suspected that a variety of biological consequences such as increases in skin cancer, cataracts,[3] damage to plants, and reduction ofplankton populations in the ocean's photic zone may result from the increased UV exposure due to ozone depletion.



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