breathing air, and polluting lakes and streams. At the global level, there is
concern that the rapid consumption of so many fossil fuels over such a
short period of time is resulting in worldwide climate change.
Environmental Pollution
Contaminants in the air, water, and land cause environmental pollu-
tion. Air pollution is the action of contaminating the mixture of gases
surrounding the earth, especially with human-made waste. The greatest
source of air pollution is a direct result of the burning of fossil fuels. Fuels
are consumed to produce electricity, for industrial processes, and to power
internal combustion engines. See Figure 26-2.
Air pollution: The
action of contami-
nating the mixture
of gases
surrounding the
earth, especially
with human-made
waste.
Chapter 26
612
Figure 26-1. The very conveniences that make our lives easier and improve our standard of living
are also harmful to the environment. A—Vehicle exhausts from cars and trucks are a major source
of pollutants. B—Although air quality has been improved in recent years, many major cities still
experience high levels of pollution at times.
A B
Pollutant Natural Source Human Source
Carbon dioxide Decay from oceans Wood and fossil fuel combustion
Nitrogen oxides Lightning, bacteria in soil High-temperature combustion
Sulfur dioxide Decay, volcanic eruptions Coal and oil combustion, smelting
of ores
Ozone Produced in the Smog from auto and industrial
troposphere emissions
*Particulate matter Forest fires, volcanic Waste building, road building,
eruptions, wind erosion mining
Methane Termites, anaerobic decay, Combustion, natural gas leaks
animal waste
Ammonia Anaerobic decay Sewage treatment plants
*Not a specific chemical substance, but still classified as a pollutant
Figure 26-2. Air pollution can occur through natural phenomena or human
activity. Fossil fuel consumption for transportation and power generation is
responsible for many pollutants.
G R E E N T E C H
In order to help battle
the air pollution in
California, the state
not only requires
emissions testing,
but smog testing as
well.