Air Pollution (Pollutants) Study Notes

7.1 Introduction to Air Pollution (Pollutants)

  • Learning Objective: Identify the sources and effects of air pollutants.
  • Key Concepts:
    • Types of Air Pollutants: Primary and secondary pollutants.
      • Primary Pollutants: Emitted directly from sources (e.g., CO, NOx, SO2).
      • Secondary Pollutants: Formed through chemical reactions in the atmosphere (e.g., Ozone (O3), sulfuric acid).

7.2 Air Pollution Basics

  • Coal Combustion:

    • Releases pollutants including carbon dioxide (CO2), sulfur dioxide (SO2), nitrogen oxides (NOx), toxic metals (e.g., mercury, lead), and particulate matter (PM).
    • Impacts include respiratory irritants and formation of acid rain.

  • Key Pollutants Identified by the Clean Air Act (1970):

    • Six criteria pollutants to monitor and regulate: SO2, NOx, CO, O3, PM, and lead.

7.3 Photochemical Smog

  • Formation Process:

    • Occurs when nitrogen oxides and volatile organic compounds (VOCs) react under sunlight to form pollutants.
    • Conditions affecting smog formation: temperature, sunlight intensity, and vehicle emissions.

  • Health Impacts:

    • Causes respiratory issues and eye irritation; more prominent in urban areas due to high vehicle concentration.

7.4 Thermal Inversion

  • Definition: Occurs when cooler air is trapped at the surface by warmer air above, preventing normal air circulation.

    • This leads to trapped pollutants, often increasing smog and particulate levels near ground level.

  • Effects: Can cause respiratory problems and decreased visibility, especially in urban areas.

7.5 Natural Sources of CO2 and Particulates

  • Natural Sources:
    • CO2: From respiration, decomposition, and volcanic eruptions.
    • Particulates: Dust, pollen, ash, and VOC emissions from plants contribute to natural PM.

7.6 Indoor Air Pollutants

  • Common Indoor Pollutants:
    • Carbon Monoxide (CO): Produced from incomplete combustion and can be lethal at high levels.
    • Particulates: Includes dust, mold spores, and asbestos.
    • Volatile Organic Compounds (VOCs): Emitted from home products affecting respiratory health.

7.7 Reduction of Air Pollutants

  • Methods for Reduction:

    • Regulatory measures like the Clean Air Act established standards for air quality.
    • The use of catalytic converters to reduce auto emissions and technology to scrub pollutants from industrial processes.

  • Individual Actions: Driving less, conserving energy, and utilizing renewable energy sources.

7.8 Acid Rain

  • Cause: Result of emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx).
    • Primary sources include coal-burning power plants and vehicles.
  • Effects: Acidification of ecosystems, soil nutrients leaching, and increased solubility of toxic metals leading to environmental harm.