The Ozone Layer and Climate Change

Introduction

Ozone (o3) IS a form of oxygen that forms naturally in the atmosphere and also as a result of some electrical activity. It has a characteristic odor and is an irritating and toxic gas at even low concentrations. Ozone plays a vital role in shielding the surface of the earth from damaging ultraviolet radiation. In recent years, ozone has become increasingly depleted as a result of the emission of man-made chemicals into the air. Fears of widespread damage to the ozone layer—which some believe have led to such diseases as skin cancer—have prompted concerted action to repair the problem.

Ozone is present in the stratosphere, which is a layer in the atmosphere from 10 to 50 kilometers above the surface of the earth. This is the height at which airplanes are flown. Ozone in the stratosphere acts as the primary shield against ultraviolet (UV) radiation. Without ozone, severe cellular damage to nearly all forms of life on earth would result. In humans, UV radiation darkens the skin and destroys cells depending on the position within the UV spectrum it occupies. UV radiation is defined as being between 40 and 400 nm, which occupies the space between X-rays and visible light. Excessive UV radiation can lead to the formation of skin cancers and cataracts, in addition to sunburn (erythema).

By passing an electrical discharge through a stream of normal, diatomic oxygen (O2), ozone may be manufactured. It has a number of industrial applications, including chemical oxidation, organic syntheses, and water disinfection. It can decolorize and deodorize a number of substances, which is useful for consumer goods. Depending on the presence of certain other catalysts, ozone may rapidly decompose at everyday temperatures or at the boiling point of water and above. This and the toxicity of the gas mean that it must be handled with some care.

The amount of ozone in the stratosphere has historically been constant, although processes of formation and destruction of individual ozone molecules is continuous. The total amount has varied within predictable and fairly well-established levels, depending on changes in seasonality and latitude and on the changing prevalence of sunspots. However, it has become increasingly obvious in recent years that the depletion of atmospheric levels of ozone has exceeded all known precedent and may have reached a level beyond which natural restorative processes will replenish it. The reason for this is due to the release of chlorofluorocarbon gases (CFCs) into the atmosphere. CFCs have been used in consumer goods and industrial applications since their development some 50 years ago. They are customarily low in toxicity, nonflammable, and stable and of great value as refrigerants, solvents, and fire retardation agents, among other uses.

Unfortunately, it is the stability of these compounds that causes the problem as it permits the chlorine-bearing compounds to be released into the atmosphere when the substances begin to deteriorate. Although chlorine has been extensively used in human society in such applications as hygiene in swimming pools, this chlorine does not reach the upper atmosphere ...