Air Pollution: Causes, Effects, and Control, Slides of Environmental Science

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Chapter 20

Air Pollution

Overview of Chapter 20

• Atmosphere as a Resource
• Types and Sources of Air Pollution
  • Major Classes of Air Pollutants
  • Sources of Outdoor Air Pollutants
  • Urban Air Pollution
• Effects of Air Pollution
• Controlling Air Pollution in the US

Types and Sources of Air Pollution

• Air Pollution
  • Chemicals added to the atmosphere by natural events or human activities in high enough concentrations to be harmful
• Two categories
  • Primary Air Pollutant
    • Harmful substance that is emitted directly into the atmosphere
  • Secondary Air Pollutant
    • Harmful substance formed in the atmosphere when a primary air pollutant reacts with substances normally found in the atmosphere or with other air pollutants

Major Air Pollutants

Major Classes of Air Pollutants

• Particulate Material
• Nitrogen Oxides
• Sulfur Oxides
• Carbon Oxides
• Hydrocarbons
• Ozone

Particulate Material

• Thousands of different solid or liquid particles

suspended in air

• Includes: soil particles, soot, lead, asbestos, sea salt, and sulfuric acid droplets
• Dangerous for 2 reasons
• May contain materials with toxic or carcinogenic effects
• Extremely small particles can become lodged in lungs

Carbon Oxides and Hydrocarbons

• Carbon Oxides
  • Gases carbon monoxide (CO) and carbon dioxide (CO 2 )
  • Greenhouse gases
• Hydrocarbons
  • Diverse group of organic compounds that contain only hydrogen and carbon (ex: CH 4 - methane)
  • Some are related to photochemical smog and greenhouse gases

Ozone

• Tropospheric Ozone
  • Man- made pollutant in the lower atmosphere
  • Secondary air pollutant
  • Component of photochemical smog
• Stratospheric Ozone
  • Essential component that screens out UV radiation in the upper atmosphere
  • Man- made pollutants (ex: CFCs) can destroy it

Urban Air Pollution

• Photochemical Smog (ex: Los Angeles below)
  • Brownish-orange haze formed by chemical reactions involving sunlight, nitrogen oxide, and hydrocarbons

Formation of Photochemical Smog

Case-In-Point Air Pollution in Beijing and

Mexico City

• Beijing (left)
• Mexico City (above)

Effects of Air Pollution

• Low level exposure
  • Irritates eyes
  • Causes inflammation of respiratory tract
• Can develop into chronic respiratory diseases

Children and Air Pollution

• Greater health threat to children than adults
  • Air pollution can restrict lung development
  • Children breath more often than adults
• Children who live in high ozone areas are

more likely to develop asthma

Controlling Air Pollution in US

• Smokestacks with

electrostatic precipitator

(right)

Without Electrostatic precipitator

With Electrostatic precipitator