OZONE LAYER DEPLETION AND ITS EFFECTS

The ozone (O3) layer of the Earth's upper atmosphere exists from 50,000 to 120,000 feet (10:2127). Ozone at this level of the earth's atmosphere is generated by the absorption of ultraviolet radiation by oxygen (O2). In forming ozone, ultraviolet radiation of wavelengths between 290 and 320 manometers is absorbed and thus not allowed to reach the surface of the Earth. Concentrations of ozone are a few parts per million, variously estimated between 5 and 10 ppm (10:2127). Unstable ozone molecules are also constantly being created and destroyed by complex natural forces involving solar radiation and interactions with very minute quantities of other gases. Ozone concentrations fluctuate naturally on a daily, seasonal, and solar-cyclical basis (3:115).

In 1973, Richard Stolarski and Ralph Cicerone, two scientists from the University of Michigan, were exploring the possible side effects of the chemical emissions from NASA rockets on the stratosphere (3:113). Stolarski and cicerone theorized that chlorine emitted into the stratosphere could unleash a complicated chain reaction that would continually destroy ozone for decades. A year later, Mario Molina and Sherwood Rowland at the University of California at Irvine became intrigued with the peculiar properties of trichlorofluromethane and dichlorodiflouromethane (CFMs), then used in the United States as both a refrigerant and as a propellant for comm

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e hole was so deep that ozone in some regions of the stratosphere virtually disappeared for a period in the early Antarctic spring (5:17). High altitude balloon measurements made over Antarctica's McMurdo Station in 1989 showed a drop in ozone levels from a normal 200 to 225 Dobson units, to a level of 103 Dobson units. Dobson units are the ratio of radiation intensity obtained by comparison of a normative ozone content and an actual ozone intensity. (10:947). In 1990, the Total Ozone mapping Spectrometer (TOMS) aboard NASA's Nimbus 7 measured the Antarctic ozone level at 133 Dobson units (6:198). In 1991, TOMS measured the Antarctic ozone level at 110 Dobson units (7:245).The Ozone Assessment Panel, sponsored by the United Nations' Environment Program and the World Meteorological organization, noted that concentrations of ozone around the world reached record lows in 1992 and 1993. The springtime Antarctic ozone hole set records in 1992 and 1993 for the largest ozone depleted area and lowest ozone levels recorded (8:187). Concurrent Effects of CFM Release Any phenomena that alters the concentration of ozone in the upper atmosphere can greatly reduce the shielding effects from damaging ultraviolet radiation (DUV) that ozone
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Approximate Word count = 1836
Approximate Pages = 7 (250 words per page)

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