Visualizing Environmental Science

206 CHAPTER 8 Air and Air Pollution

Clean gas

out

Electrode

(negative charge)

Dust falls off

wall into

collector

Dirty gas

(smoke) in

Precipitator wall

(positive charge)

Kodda/ Shutterstock

Adapted from Joesten, M.D. and Wood, J.L.

World of Chemistry,

2e.

Philadelphia: Saunders College Publishing (1996).

Image Source / Getty Images

a. In an electrostatic precipitator, the electrode imparts a negative charge to

particulates in the dirty gas. These particles are attracted to the positively charged

precipitator wall and then fall off into the collector.

b. Industrial stacks without emission control devices

can release substantial amounts of particulate

matter and other pollutants.

c. Effective emission control devices can reduce

particulate matter and other pollutants.

fuel-efficient automobiles produce fewer polluting emis-

sions, for example.

The primary objections to using these technologies

is cost. Adding scrubbers or electrostatic precipitators to

existing plants increases the cost of doing business. Like-

wise, adding catalytic converters to automobiles increases

their price. Several methods exist for removing sulfur ox-

ides from flue (chimney) gases, but it is often less expen-

sive simply to switch to a low-sulfur fuel such as natural gas

or even to a non–fossil fuel energy source, such as solar

energy. Sulfur can also be removed from fuels before they

are burned.

Reduction of combustion temperatures in automo-

biles lessens the formation of nitrogen oxides. Use of

mass transit reduces automobile use, thereby decreasing

1. Summarize the effects of the Clean Air Act on
   U.S. air pollution.


2. Contrast air pollution in highly developed
   countries and in developing countries.

T

echnology exists to control all the forms of
air pollution discussed in this chapter.
Smokestacks fitted with electrostatic precipi-
tators, fabric filters, scrubbers, and other
technologies remove particulate matter from the air
(Figure 8.14). Careful land-excavating activities, such as
sprinkling water on dry soil being moved during road
construction, reduces the creation of particulate matter.
Many of the measures that increase energy efficiency and
conservation also reduce air pollution. Smaller, more

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Controlling Air Pollutants

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