The major sources of energy in the United States are coal,
petroleum, and natural gas, all of which are known as fossil fuels.
Fossil fuels were formed millions of years ago by the decomposition
of animals and plants and thus are in limited supply. We are quickly
depleting the available fossil fuels.
Coal is solid and is composed of large hydrocarbons
and other compounds that contain sulfur, oxygen, and nitrogen. When
it’s combusted, the sulfur it contains is converted to SO2,
which is an air pollutant. Petroleum is a liquid made
up of hundreds of different components, but mostly hydrocarbons.
It also contains some compounds that have functional groups containing
sulfur, nitrogen, or oxygen. The first step in refining (processing)
petroleum is to separate it into fractions based on the different
boiling points of its components. Natural gas consists
of hydrocarbons in the gas phase, primarily methane (CH4).
Air pollution is the contamination of air by a variety
of substances, causing health problems and damaging our environment.
It has thinned the ozone layer above the earth, exposing us to harmful
UV radiation from the sun. Some of the major pollutant gases are listed
Carbon monoxide: CO is produced from incomplete
combustion of all types of natural and synthetic products, including
cigarette smoke. When it builds up in high concentrations, it can
be very toxic. Cities with heavy traffic problems are known for
dangerous CO levels.
Carbon dioxide: CO2 is
the principal greenhouse gas and is primarily responsible for the greenhouse
effect. It can be formed from all types of common human activity,
such as burning fuels and even breathing.
or CFCs, are used in great quantities in industry, for refrigeration
and air-conditioning, and in consumer products. When released into
the air, they rise into the stratosphere, where they readily react
with the ozone that constitutes the ozone layer, effectively degrading
Ozone: O3 gas occurs
naturally in the upper atmosphere, where it shields the earth from the
sun’s dangerous ultraviolet rays. When found at ground level, however,
it’s a pollutant. It can cause damage to humans (especially our
respiratory system), the environment, and a wide range of natural
and artificial materials. Vehicle exhaust and industry waste are
major sources of ground-level ozone.
Nitrogen oxide and sulfur dioxide: NOx and
SOx are major contributors
to smog and acid rain. These gases both react with volatile organic
compounds to form smog, which can cause respiratory problems in
humans. Acid rain can harm vegetation, change the chemistry of river
and lake water by lowering the pH so that it’s harmful to animal
life, and react with the marble of statues and buildings and decompose