Overview

At least from the standpoint of how long we can last in its absence, air is the most critical of all human needs. We can survive for weeks without food, days without water, but only minutes without air. Like Seneca, the first century philosopher, we readily notice some acute effects of contaminated air. Unfortunately, however, some of the more toxic pollutants are not readily detectable with normal human senses. Interestingly, Seneca reported two of the major pollution types that are regulated commonly today, volatile compounds (i.e., vapors) and particulate matter (i.e., soot). The atmosphere has been affected by human activities for millennia, but only recently has the air been polluted on a scale and to a degree that natural processes have not be able to neutralize the widespread effects.

One of the first recorded episodes of air pollution was that of the village of Hit, west of ancient Babylon. In 900 B.C., the Egyptian King Tukulti described an offensive odor emanating from a bitumen mining operation that released high concentrations of sulfur dioxide (SO ₂) and hydrogen sulfide (H ₂S). The former is the result of oxidation and the latter is the reduction of the rather ubiquitous element sulfur. Even though these problems were for...