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:


                        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)

    1. Grants EPA authority to regulate automobile emissions.
    2. Lead removed from gasoline which resulted in a 78% drop in lead pollution (1988-1995).
    3. 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.