Introduction to Pollution

• Three Categories of Constituents of the Atmosphere

  • Major components: Nitrogen (N₂), Oxygen (O₂), Argon (Ar)

  • Trace components: Carbon Dioxide (CO₂), Methane (CH₄), Nitrous Oxide (N₂O), and others.

• Definition of Pollutants

  • Primary Pollutants: Emitted directly in harmful form (e.g., soot, CO).

  • Secondary Pollutants: Formed from primary pollutants through reactions (e.g., O₃, sulfuric acid).

• Photochemical Smog Formation

  • Involves sunlight-induced reactions between nitrogen oxides and volatile organic compounds (VOCs).

  • Chemical equation: NO₂ (nitrogen dioxide) → NO (nitric oxide) + O (oxygen) → O₃ (ozone).

• Aerosols Removal

  • Removal based on size: larger aerosols are removed by gravity, while smaller particles may take longer to settle.

• Pressure in the Atmosphere

  • Pressure decreases with altitude due to the weight of air (hydrostatic pressure).

A Brief History of Air Pollution

• Natural and anthropogenic pollutants recognized since 1550.

• Recognized events:

  • Acid rain noted in the 17th century.

  • Term "smog" introduced in 1905—a blend of smoke and fog.

Sources of Air Pollution

• Natural Sources:

  • Volcanic eruptions

  • Hydrocarbons from trees

• Human Activities:

  • Motor vehicles, coal-burning power plants.

Types of Pollutants

• Primary Pollutants: Directly emitted (e.g., CO, SO₂).

• Secondary Pollutants: Result from reactions of primary pollutants (e.g., ozone, acid rain).

Acid Deposition

• Formation and effects:

  • Mixture of dry and wet acidic deposition over significant distances.

  • PH values:

    • Normal precipitation: 5.6

    • Acid rain: <5.6

  • Sources include coal power plants, vehicles.

Impacts of Pollution

• Human Health:

  • Respiratory diseases (asthma, bronchitis).

  • Correlation with hospital admissions due to pollution exposure.

• Material Damage:

  • Corrosion of buildings, monuments, and vehicles.

• Ecological Effects:

  • Fish abnormalities, diminished crop yields, leaching of nutrients from soil.

Smog Types

• Photochemical Smog:

  • Formed from sunlight reactions with pollutants; associated with urban areas.

• Sulfurous Smog:

  • Caused by coal burning; predominantly gray in appearance.

Criteria Pollutants**

• Six primary criteria pollutants to monitor:

  • Sulfur Dioxide (SO₂)

  • Nitrogen Oxides (NOₓ)

  • Carbon Monoxide (CO)

  • Ozone (O₃)

  • Particulate Matter (PM)

  • Lead (Pb)

Effects of Air Pollution

• Human Health Impacts:

  • Toxic poisoning, cancers, respiratory irritation.

  • Increased morbidity rates from chronic diseases.

• Environmental Effects:

  • Damage to plants and ecosystems due to acid deposition.

• Visibility Impairment:

  • Reduced visibility due to particulate matter and smog formation.

Ozone Layer and UV Radiation

• Stratospheric Ozone:

  • Absorbs harmful UV radiation; affected by CFCs.

• Ozone Depletion:

  • Resulting health risks: skin cancer, reduced agricultural yields.

Climate Interactions

• Changes in atmospheric composition and circulation influence weather patterns and ecological balance.

  • Includes the hydrological cycle, ocean interactions, and land use changes.

Conclusion

• Understanding pollution sources, effects, and regulations is critical for improving air quality and protecting health. Efforts to curb pollution contribute to a healthier environment and quality of life for all.

• Important to continue research and take action against both natural and anthropogenic pollutants to foster sustainable air quality management practices.