• The build up of harmful substances in the
air to unhealthy levels causes air pollution.
• A pollutant that is put directly into the air
by human activity is called a primary
pollutant. (ex. Soot from smoke)
• Secondary pollutants form when
primary pollutants react with other
primary pollutants or with naturally
occurring substances such as water
vapor. (ex. Ground-level ozone that
forms when sunlight and car
emissions react with oxygen)
Primary pollutants from household
products, power plants, and motor
Motor Vehicle Emissions
Industrial Air Pollution
Air pollution that hangs over an
urban area and reduces visibility is
Temperature inversion occurs
when the air above is warmer than
the air below and traps pollutants in
the cooler air.
• Acid precipitation is precipitation that
contains high concentrations of acids.
• When fossil fuels are burned, they release
oxides of sulfur and nitrogen. The oxides
combine with water vapor in the
atmosphere and form sulfuric acid and
• pH is a measure of how acidic or basic a
Acid precipitation affects soil and
• An increase in the concentration of acid in
the soil and water is called acidification.
• The increased levels of acid affect the
ability of plants to take in nutrients. In
addition, it clogs the surfaces of plants.
Acid in Aquatic Ecosystems
• Changes in pH can kill fish and other
aquatic animals. Acid precipitation causes
aluminum to build up in the ecosystem
which will accumulate in the gills of fish
and suffocate them.
• Can cause fish and amphibians to produce
fewer eggs, eggs that do not hatch, and an
increase birth defects of the offspring
Acid Precipitation and Humans
• Causes respiratory problems
• Decreases available food (fish)
• Dissolves building materials (important
monuments and buildings)