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 commercial products (10:2127). Molina and Rowland's research showed that, unlike most other gases, CFMs were not chemically destroyed or quickly altered in the lower atmosphere. CFMs slowly migrated up to the stratosphere where they remained intact for decades (10:2127). The two researchers concluded that CFCs are eventually broken down by radiation, thereby releasing large quantities of chlorine (3:114). Thus released, chlorine atoms could serve as a catalyst in a complex series of reactions, pa...