Unit 7: Atmospheric Pollution

Unit 7: Atmospheric Pollution Notes

7.1 Introduction to Air Pollution

  • Learning Objective: Identify the sources and effects of air pollutants.
  • Essential Knowledge:
    • Coal combustion releases pollutants: CO2, SO2, toxic metals, and particulates.
    • Fossil fuels release nitrogen oxides, contributing to ozone production, photochemical smog, and acid rain.
    • Other pollutants from fossil fuels include carbon monoxide, hydrocarbons, and particulate matter.
    • The Clean Air Act regulated lead in fuels, significantly reducing atmospheric lead levels.
    • Primary Pollutants: Directly emitted pollutants (e.g., CO, CO2).
    • Secondary Pollutants: Transformations of primary pollutants (e.g., ozone).

7.1.1 Sources of Air Pollution

  • Natural Sources:
    • Volcanoes, lightning, forest fires, plant emissions (e.g., VOCs).
  • Anthropogenic Sources:
    • On-road vehicles, power plants, industrial processes, waste disposal.

7.1.2 Types of Pollutants

  • Primary Pollutants:
    • Examples: CO, CO2, SO2, NOx, suspended particulate matter.
  • Secondary Pollutants:
    • Examples: Ozone, sulfate, nitrate formed from chemical transformations.
  • Health Impacts: Respiratory issues, smog, and environmental damage.

7.2 Photochemical Smog

  • Learning Objective: Explain the causes, effects, and reduction methods for photochemical smog.
  • Essentials:
    • Formed by reactions of nitrogen oxides and VOCs in sunlight.
    • Effects include respiratory problems, eye irritation, and environmental damage.
    • Can be reduced by cutting nitrogen oxides and VOC emissions.

7.2.1 Conditions for Formation

  • High temperatures (especially in summer), presence of NOx and VOCs, often exacerbated by urban vehicle emissions.

7.3 Thermal Inversion

  • Learning Objective: Describe thermal inversion and its relationship with pollution.
  • Definition:
    • Occurs when a layer of warm air traps cooler air and pollutants close to the ground.
  • Effects: Increased pollution concentration, worsening respiratory issues.

7.4 Atmospheric CO2 & Particulates

  • Learning Objective: Understand natural sources of CO2 and particulates.
  • Natural Sources: Volcanic eruptions, respiration, decomposition.
  • Particulate Matter: Can scatter light, reducing photosynthesis and visibility.

7.5 Indoor Air Pollutants

  • Classifications:
    • Indoor pollutants from combustion: CO, SO2, NOx, particulates.
    • Common pollutants: VOCs (from cleaners, furniture), radon, mold.
  • Health Risks: Higher levels indoors than outdoors, significant health risks from poor IAQ.

7.6 Reduction of Air Pollutants

  • Methods:
    • Use of vapor recovery nozzles, catalytic converters, and scrubbers.
    • Encourage walking, biking, and increased use of energy-efficient technologies.

7.7 Acid Rain

  • Learning Objective: Describe acid deposition and its effects.
  • Sources: Nitrogen oxides and sulfur oxides from vehicles and power plants.
  • Impacts: Soil and water acidification, damage to structures and forests.

7.8 Noise Pollution

  • Definition: Noise levels causing physiological stress and hearing loss.
  • Sources: Transportation, construction, industrial activity.
  • Effects on Organisms: Stress, disrupted communication, migratory changes.
  • Health Impacts: Cognitive difficulties in children, increased blood pressure, and psychological stress.