Detailed Air Pollution Notes

Introduction to Air Pollution

• Definition: Air pollution refers to the presence of substances in the atmosphere that can be harmful to human health and the environment.

Sources and Effects of Air Pollutants

• Coal Combustion:
  • Releases pollutants such as:
  • Carbon Dioxide (CO_2)
  • Sulfur Dioxide (SO_2)
  • Toxic metals (e.g., mercury, arsenic, lead)
  • Particulates (PM)
• Fossil Fuel Combustion:
  • Releases nitrogen oxides (NOx), which lead to:
  • Ozone production
  • Formation of photochemical smog
  • Acid rain formation (converted to nitric acid)
• Primary vs Secondary Air Pollutants:
  • Primary Pollutants: Emitted directly from sources (e.g., NOx, CO, SO_2).
  • Secondary Pollutants: Formed through chemical reactions in the atmosphere (e.g., O_3, sulfuric acid).
• Regulations (Clean Air Act):
  • EPA regulates lead emissions, significantly reducing lead in the atmosphere.

Specific Air Pollutants

• Sulfur Dioxide (SO_2):
  • A respiratory irritant that worsens ailments like asthma and bronchitis.
  • Contributes to the formation of acid rain.
• Nitrogen Oxides (NO and NO_2):
  • Produced from combustion processes (especially fossil fuels).
  • Linked to respiratory irritation and photochemical smog formation.
• Carbon Monoxide (CO):
  • A toxic gas produced by incomplete combustion of fuels.
  • Asphyxiant by binding to hemoglobin.
• Ozone (O_3):
  • Ground-level ozone is harmful and contributes to respiratory problems.

Photochemical Smog

• Formation: Caused by reactions between NO_x and volatile organic compounds (VOCs) in the presence of sunlight.
• Conditions Favoring Formation:
  • Warm temperatures.
  • High sunlight exposure.
  • High traffic areas increase NO2 emissions leading to O3 accumulation.

Thermal Inversion

• Definition: A situation where the normal temperature gradient is inverted; cooler air near the ground is trapped under warmer air above.
• Effects: This can trap pollutants such as smog and particulates close to the Earth’s surface, worsening air quality.

Natural and Indoor Air Pollutants

• Natural Sources of CO_2: Found from respiration, decomposition, volcanic eruptions.
• Indoor Air Pollutants: Common pollutants include:
  • Carbon monoxide (from combustion)
  • Particulates (asbestos, dust)
  • Volatile Organic Compounds (from household products)
  • Radon (from soil and building materials)

Reduction of Air Pollutants

• Methods:
  • Regulatory Practices: Implementing standards for emissions.
  • Technological Innovations:
  • Catalytic Converters: Reduce emissions from vehicles.
  • Scrubbers: Remove pollutants from industrial emissions.
  • Behavioral Changes: Promoting public transportation, reducing fossil fuel use.

Acid Rain

• Formation: Resulting from NOx and SO2 emissions that mix with atmospheric moisture, forming nitric and sulfuric acids.
• Impacts: Acidifies soil and water bodies, harming aquatic life and vegetation.
• Mitigation Strategies:
  • Use of limestone to neutralize acidic soils.
  • Reducing emissions through cleaner energy sources.

Key Takeaways

• Health Effects of Air Pollution: Respiratory illness, cardiovascular issues.
• Environmental Effects: Damage to ecosystems, reduced biodiversity, and impaired agricultural productivity.