Air Pollution

Types of Pollutants

  • Primary Pollutants: Emitted directly into the air.

  • Secondary Pollutants: Form from reactions of primary pollutants.

  • Point Source: Pollution from a specific source.

  • Nonpoint Source: Pollution from widespread or less identifiable sources.

  • Developing Countries: Typically pollute more due to weaker regulations.

  • Measurement: Concentration is in parts per million (ppm).

Major Pollutants

  • Criteria Air Pollutants: 6 pollutants from the Clean Air Act:

    • Sulfur Dioxide (SO2): Causes acid rain; reduced in the US.

    • Carbon Monoxide (CO): Produced from incomplete combustion; harmful in high concentrations.

    • Carbon Dioxide (CO2): Included as a pollutant due to climate change.

    • Nitrogen Dioxide (NO2): Forms nitric acid and contributes to smog and health issues.

    • Ozone (O3): Major component of photochemical smog; harmful to health and materials.

    • Lead: Neurotoxic; previously used in fuels.

    • Suspended Particulate Matter (PM10): Causes lung damage; includes various harmful particles.

    • Volatile Organic Compounds (VOCs): Found in household products; many are carcinogenic.

Smog Types

  • Industrial Smog: Sulfur-based, characterized by gray air.

  • Photochemical Smog: Nitrogen-based, worsened by UV radiation, resulting in brown air.

Photochemical Smog Formation

  • Involves reactions between NOx, sunlight, and VOCs producing ozone.

Case Studies

  • China: High coal burning leads to severe health impacts; recent efforts to improve air quality include financial incentives for cleaner energy.

  • Great Smog of 1952, London: A major pollution event leading to thousands of illnesses and deaths.

Clean Air Act (1970)

  • Targeted criteria pollutants like lead (removed from gasoline) and introduced catalytic converters.

Catalytic Converters

  • Convert harmful emissions to less toxic substances but can't eliminate CO2 or N2O.

Temperature Inversion

  • A phenomenon that traps pollution close to the ground, worsening smog during certain weather conditions.