Earth Science
Chapter 15
Section 2
A. Air Quality:
Harmful substances in the air, water or soil are known as
pollutants.
Most air pollution is the result of burning fossil fuels such as
coal, oil, gasoline and diesel fuel.
Burning fossil fuels produces a number of air pollutants,
including, particles and gases that can form smog and acid
rain.
B. Particles:
Natural Sources:
Salt from ocean spray
Molds and pollen by winds
Forest fires, dust storms, soil erosion,
Volcanoes put ash and dust and poisonous gases into the
atmosphere.
Human Activities:
Burning fossil fuels
Construction and farming
C. Smog:
The brown haze that forms over cities is called
photochemical smog.
A fossil fuel gives off unburned hydrocarbons, a substance
composed of carbon and hydrogen.
The burning of these fuels causes the some of the nitrogen in
the air to combine with oxygen forming nitrogen oxides.
The nitrogen oxides, hydrocarbons and other air pollutants
then react with one another in the presence of sunlight to
form a mix of ozone and other chemicals, called
photochemical fog.
D. Temperature Inversion:
During normal atmospheric conditions warm air at the
surface rises and pollutants are carried away.
During a temperature inversion a layer of warm air prevents
the rising air from escaping.
The polluted air is trapped and held close to the earth’s
surface. The smog becomes more concentrated and
dangerous.
E. Acid Rain:
One result of air pollution is acid rain.
Acid rain forms when nitrogen oxides and sulfur oxides
combine with water in the air to form nitric acid and sulfuric
acid.
Acid rain can make water so acidic that plants, amphibians,
fish and insects can no longer survive in it.
F. Improving Air Quality:
Filtering smoke stacks
Improvements in Auto exhaust emissions
Some people think stricter regulations are needed.
Others believe reducing pollution is too expensive.