Page 21 - Air Pollution Control Engineering

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2 Lawrence K. Wang et al.

Lightning, another large contributor to atmospheric pollution, activates atmospheric
oxygen (O ) to produce ozone (O ), a poisonous gas [ozone in the upper atmosphere,
2 3
however, acts as a shield against excessive amounts of ultraviolet (UV) radiation, which
can cause human skin cancer]. In addition to the production of ozone, lightning is the
indirect cause of large amounts of combustion-related air pollution as a result of forest
fires. The Forest Service of the United States Department of Agriculture reported that
lightning causes more than half of the over 10,000 forest fires that occur each year.
For centuries, human beings have been exposed to an atmosphere permeated by other
natural pollutants such as dust, methane from decomposing matter in bogs and swamps,
and various noxious compounds emitted by forests. Some scientists claim that such nat-
ural processes release twice the amount of sulfur-containing compounds and 10 times
the quantity of carbon monoxide (CO) compared to all human activity.
Why, then, is society so perturbed by air pollution? The concern stems from a combi-
nation of several factors:

1. Urbanization and industrialization have brought together large numbers of people in
small areas.
2. The pollution generated by people is most often released at locations close to where they
live and work, which results in their continuous exposure to relatively high levels of the
pollutants.
3. The human population is still increasing at an exponential rate.
Thus, with rapidly expanding industry, ever more urbanized lifestyles, and an increas-
ing population, concern over the control of man-made air pollutants is now clearly a
necessity. Effective ways must be found both to reduce pollution and to cope with existing
levels of pollution.
As noted earlier, natural air pollution predates us all. With the advent of Homo sapiens,
the first human-generated air pollution must have been smoke from wood burning, followed
later by coal.
From the beginning of the 14th century, air pollution from coal smoke and gases
had been noted and was of great concern in England, Germany, and elsewhere. By
the beginning of the 19th century, the smoke nuisance in English cities prompted the
appointment of a Select Committee of the British Parliament in 1819 to study and report
on smoke abatement.
Many cities in the United States, including Chicago, St. Louis, and Pittsburgh, have
been plagued with smoke pollution. The period from 1880 to 1930 has often been called
the “Smoke Abatement Era.” During this time, much of the basic atmospheric cleanup
work started. The Smoke Prevention Association was formed in the United States near
the turn of the 20th century, and by 1906, it was holding annual conventions to discuss the
smoke pollution problem and possible solutions. The name of the association was later
changed to the Air Pollution Control Association (APCA).
The period from 1930 to the present has been dubbed the “Disaster Era” or “Air
Pollution Control Era.” In the most infamous pollution “disaster” in the United States, 20
were killed and several hundred made ill in the industrial town of Donora, Pennsylvania
in 1948. Comparable events occurred in the Meuse Valley, Belgium in 1930 and in
London in 1952. In the 1960s, smog became a serious problem in California, especially
in Los Angeles. During a 14-day period from November 27 to December 10, 1962, air