Afflictions of the industrial age, air and water pollution rank among the most vexing examples of the law of unintended consequences. In trying to make the world more livable, humans have succeeded in fouling not only their own nests, but also those of many fellow creatures.
The poisons in the air include nitrogen dioxide, sulfur dioxide, carbon monoxide, soot, lead, and ground-level ozone. Ordinarily, wind disperses them. But the wind does not always blow. In London’s winter of 1952 there was a temperature inversion: A cold layer of air settled under a warm layer, slowing the dispersion and allowing pollutants to accumulate close to the ground. The result was the worst air pollution disaster ever recorded.
A partner-in-crime of air pollution, acid rain—widely blamed on industrial emissions—has eroded buildings, harmed crops and forests, and threatened life in freshwater lakes. In 1995, 47 percent of all hazardous emissions in the United States came from transportation—mostly cars and trucks. Industrial emissions accounted for 26 percent.
The good news is that U.S. emissions of most air pollutants have been dropping during the past three decades. Unfortunately, in many developing countries they are rising at precipitous rates.
