Air Pollution Overview

  • Air Pollution Definition: Introduction of chemicals, particulate matter, or microorganisms into the atmosphere at harmful concentrations.

  • Clean Air Act of 1970: Identified six criteria air pollutants:

    • Sulfur Dioxide (SO2)
    • Nitrogen Oxides (NO and NO2)
    • Carbon Monoxide (CO)
    • Particulate Matter (PM)
    • Ozone (O3)
    • Lead (Pb)

  • Carbon Dioxide (CO2): Not a criteria pollutant but contributes to greenhouse gas effect.

  • Sources of Air Pollution:

    • Coal Combustion: Major contributor; releases CO, CO2, SO2, nitrous oxides, and toxic metals.
    • Sulfur Dioxide: Respiratory irritant; can lead to acid rain and smog.

  • Nitrogen Oxides: Formed during combustion. Leads to photochemical smog and acid rain.

  • Particulate Matter: Similar sources as above; categorized as PM10 (≤10 micrometers) and PM2.5 (≤2.5 micrometers).

    • PM impacts respiratory and cardiovascular health.

  • Primary vs. Secondary Pollutants:

    • Primary: Emitted directly from sources (e.g., No, CO, VOCs).
    • Secondary: Formed by reactions of primary pollutants in the atmosphere (e.g., ozone, nitric acid).

  • Natural Pollutants: Include emissions from lightning, wildfires, and volcanic eruptions.

  • Thermal Inversion: A phenomenon where warm air traps pollutants near the Earth's surface, worsening air quality.

  • Indoor Air Pollutants:

    • Common pollutants include CO, VOCs (e.g., formaldehyde), and dust/mold.
    • Lead and radon pose serious health risks, particularly for children.

  • Photochemical Smog: Results from sunlight reacting with pollutants from vehicles and industrial sources; involves the formation of ozone and other harmful compounds.

  • Health Effects: Respiratory issues, cardiovascular diseases, irritation, and increased cancer risk from certain pollutants.