Air Quality n Pollutants are substances in the air, water, or soil that are harmful to people or the environment.
n Air pollution occurs when harmful substances end up in the air at unhealthy levels.
Air pollution may cause health
problems:
n Headaches
n Eye irritation
n Coughing
n Allergies
n Lung diseases
Most air pollution is the result of burningfossil fuels such as:
n Coal
n Oil
n Gasoline
n Diesel fuel
Motor vehicles are responsible for almost half of the air pollution
caused by human activity.
Natural air pollutants:
n Salt
n Mold
n Pollen
n Ashes
n Soil
Man-made air pollutants:
n Soot (burning wood, coal)
n Soil (from farming activities)
n Smog
n Smog
hangs over urban areas and reduces visibility.
n Smog is a result of chemical reactions involving:
Sunlight
Nitrogen Oxides
Sulfur Oxides
Hydrocarbons (methane)
n
The source of most smog is pollutants released by autos and industries.
Photochemical Smog:
n Burning fossil fuels releases nitrogen oxides, hydrocarbons, and other pollutants.
n These pollutants react with each other in the presence of sunlight to form a mix of ozone and other
chemicals called photochemical smog.
n The ozone in photochemical smog harms
people, plants, rubber, paint, and some plastics.
Acid Rain:
n The burning of coal
(fossil fuel high in sulfur) produces substances composed of oxygen and sulfur called sulfur oxides.
n Acid rain forms when nitrogen oxides or sulfur oxides combine with water in the air to form nitric acid and sulfuric
acid.
n Rain, sleet, snow, fog carry these two acids from the air to trees, lakes, and buildings.
n May make the lake or pond water too acidic to support life.
n Controlling Air Pollution
The Clean Air Act of 1970 (1990)
-
- Grants EPA authority to regulate automobile emissions.
- Lead removed from gasoline which
resulted in a 78% drop in lead pollution (1988-1995).
- Development and use of catalytic converters which clean exhaust gases of
pollutants before exiting the car’s tailpipe.
n Controlling Air Pollution
n Controlling Air Pollution from Industries
The Clean Air Act requires industries to use pollution-control devices.
n Scrubbers
work by spraying gases with water, removing the pollutants.