Air Pollution - Unit 7 Review

Introduction to Air Pollution

• Overview of key pollutants, their abbreviations, and names.
• Importance of understanding air pollution for scoring well on tests.

Types of Pollutants

• Primary Pollutants: Directly emitted from a source (e.g., NO2 from cars).
• Secondary Pollutants: Formed in the atmosphere via chemical reactions (e.g., O3).

Key Air Pollutants and Sources

• Sulfur Oxides (SOx): From coal-burning power plants.
  • Example: Sulfur dioxide (SO2).
• Nitrogen Oxides (NOx): From cars and power plants.
  • Example: Nitrogen dioxide (NO2).
• Carbon Dioxide (CO2): Naturally occurring, from respiration, decomposition, volcanoes.
  • Greenhouse gas contributing to climate change.
• Toxic Metals: From coal combustion, e.g., lead and mercury.
• Particulate Matter (PM): From combustion, cigarette smoke, forest fires.

Clean Air Act (CAA)

• US federal law regulating six major air pollutants.
• Notable regulation: Lead in gasoline.

Photochemical Smog

• Formation: NOx reacts with sunlight and VOCs to form smog.
• Sources: Car traffic (rush hour), urban areas.
• Volatile Organic Compounds (VOCs): Found in gasoline, paint, varnishes, etc.
• Environmental Effects: Smog worsens in areas with mountains/valleys.

Chemical Reactions in Smog Formation

• NO2 reacts with sunlight to form NO and an oxygen radical.
• Oxygen radical + O2 = Ozone (O3).
• With VOCs: Reaction gets hijacked preventing normal ozone breakdown, leading to smog.

Thermal Inversions

• Normal Conditions: Warm air near surface, cooler as it ascends.
• Inversion: Traps cold air with pollution below warm air.
• Famous Example: Great Smog of London, mid-1900s.

Acid Deposition

• Can be wet (rain) or dry (particulate).
• Sources: NOx and SOx mix with water to form acids.
• Effects: Environmental damage, acidification of soils/water, harm to statues/buildings.

Indoor Air Pollutants

• Natural Sources: Radon, mold, dust, asbestos.
• Man-Made Sources: Insulation, VOCs from furniture, lead in paint.
• Combustion Sources: Wood burning, tobacco smoke.

Radon

• Radioactive gas from decaying uranium.
• Enters homes through foundation cracks, particularly in basements.
• Health Risk: Second leading cause of lung cancer in the US.

Noise Pollution

• Sources: Urban transport, construction, industrial activity.
• Effects on Humans: Anxiety, hearing loss, stress.
• Effects on Animals: Disrupts communication, mating, echolocation.

Methods for Reducing Air Pollution

• Catalytic Converters: Convert NOx and CO to less harmful substances in vehicles.
• Vapor Recovery Nozzles: Capture gasoline fumes at pumps.
• Industrial Equipment: Scrubbers (water-based) and electrostatic precipitators (static-based) to remove particulates.
• Regulatory Methods: Clean Air Act in the USA.
• Fossil Fuel Reduction: Reducing fossil fuel use overall.

• Review Source: Science Panda YouTube channel for further unit reviews.