Ozone Depletion Project

Topics: Ozone depletion, Ozone layer, Ozone Pages: 3 (874 words) Published: May 31, 2012
Ozone depletion describes two distinct but related phenomena observed since the late 1970s: a steady decline of about 4% per decade in the total volume of ozone in Earth's stratosphere (the ozone layer), and a much larger springtime decrease in stratospheric ozone over Earth's polar regions. The latter phenomenon is referred to as the ozone hole. In addition to these well-known stratospheric phenomena, there are also springtime polar tropospheric ozone depletion events. The details of polar ozone hole formation differ from that of mid-latitude thinning, but the most important process in both is catalytic destruction of ozone by atomic halogens. The main source of these halogen atoms in the stratosphere is ‘photodissociation’ of man-made halocarbon refrigerants (CFCs, freons,halons). These compounds are transported into the stratosphere after being emitted at the surface. Both types of ozone depletion were observed to increase as emissions of halo-carbons increased. CFCs and other contributory substances are referred to as ozone-depleting substances (ODS). Since the ozone layer prevents most harmful UVB wavelengths of ultraviolet light (UV light) from passing through the Earth's atmosphere, observed decreases in ozone have generated worldwide concern leading to adoption of protocols that ban the production of CFCs, halons, and other ozone-depleting chemicals. It is suspected that a variety of biological consequences such as increases in skin cancer, cataracts, and damage to plants result from the increased UV exposure due to ozone depletion. There are several misconceptions about ozone layer depletion, many of which have been scientifically proven to be erroneous and quite possible. The five biggest misconceptions are discussed below. 1. CFC’s are too heavy to reach the stratosphere- Since CFC molecules are heavier than air (nitrogen or oxygen), it is commonly believed that the CFC molecules cannot reach the stratosphere in significant amount. But atmospheric...
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