EET CHAPTER 6

• Air pollution


  The addition of gas, particles or odors to our atmosphere
• Sources of air pollution

  • Natural (volcanoes, wildfire, earthquakes, dust storms)
  • Artificial (human activities)
• Pollutant


  Any undesirable foreign matter added to the environment
• Environmental pollution


  The introduction of contaminants into the environment that causes harm or discomfort to the ecosystem
• Pollution endangers life on earth
• Atmosphere


  • 78% Nitrogen
  • 21% Oxygen
  • 1% Argon, CO2, Water vapor
• Primary pollutants


  Pollutants emitted directly into the environment (e.g. smoke, dust, SO2, CO2, hydrocarbons)
• Secondary pollutants


  Pollutants that form in the air when primary pollutants react (e.g. ground level ozone, PAN, aldehydes)
• Types of air pollutants

  • Gaseous pollutants (oxides of C, N, S, H2S, Hydrocarbons)
  • Particulate matter (smoke, dust, fumes, smog, fog)
• Primary pollutant


  Pollutant put directly into the air by human activity
• Secondary pollutant


  Primary pollutant reacts with other primary pollutants or with naturally occurring substances
• Major air pollutants

  • Sulfur dioxide (SO2)
  • Nitrogen Oxides (NOx)
  • Carbon Monoxide (CO)
  • Particulate Matter (PM)
  • Ozone (O3)
  • Lead (Pb)
• Sulfur dioxide (SO2)


  About 1/3 occurs naturally, 2/3 from human sources (mostly metal production & combustion of coal and oil)
• Formation of sulfuric acid (acid rain)

  1. S + O2 = SO2 (Primary Air Pollutant)

  2. 2 SO2 + O2 = 2 SO3 (Secondary Air Pollutant)

  3. SO3 + H2O = H2SO4 (Sulfuric Acid)
• Anthropogenic (human-made) sources of air pollution

  • On-road vehicles
  • Power plants
  • Industrial processes
  • Waste disposal (incineration)
• Carbon monoxide (CO)


  Highly toxic gas produced when organic materials are burned with insufficient oxygen
• 93% of carbon dioxide (CO2) in troposphere occurs as a result of the carbon cycle (7% anthropogenic)
• Nitrogen oxides (NOx)

  Form when nitrogen and oxygen gas in air react at high-combustion temperatures in automobile engines and coal-burning plants
• Ozone (O3)


  Highly reactive gas that is a major component of photochemical smog, can cause respiratory illness and damage plants
• Lead (Pb)


  Heavy metal with neurologic effect, accumulates in the body and can cause mental retardation and kidney damage
• Volatile organic compounds (VOCs)


  Include industrial solvents, paints, fuels, contribute to formation of photochemical smog
• Particulate matter (PM)


  Consists of solid particles and liquid droplets, most harmful forms are fine particles (PM-10) and ultrafine particles (PM-2.5)
• PM causes ~60,000 premature US deaths per year
• Natural sources of air pollution

  • Volcanoes
  • Forest fires
  • Sandstorms
  • Methane from livestock
• Smog


  Air pollution that hangs over urban areas and reduces visibility, caused mainly by auto and industrial exhaust
• Effects of smog

  • Respiratory problems (asthma, emphysema, chronic bronchitis)
  • Eye irritations
  • Reduced resistance to colds and lung infections
  • Inhibits plant growth
  • Damages crops
• Acid rain


  Any form of precipitation with acidic components, such as sulfuric or nitric acid, that falls to the ground from the atmosphere
• Formation of acid rain

  1. Fossil fuels are burned, releasing sulfur & nitrogen oxides in the atmosphere

  2. SO2 and NOx react with water vapor forming mild solution of sulfuric acid & nitric acid

  3. Acid precipitation falls into lakes, rivers, & streams; killing organisms that live there
• Effects of acid rain on living things

  • Chronic bronchitis
  • Eye irritations
  • Reduced resistance to colds and lung infections
• Effects of acid rain on plants

  • Inhibits plant growth
  • Damages crops
• Acid rain


  Any form of precipitation with acidic components, such as sulfuric or nitric acid that fall to the ground from the atmosphere in wet or dry forms
• Two forms of acid deposition

  • Dry acidic gases & particles
  • Wet acid rain, fog, sleet, cloud vapor & snow
• Formation of acid rain

  1. Fossil fuels are burned, releasing sulfur & nitrogen oxides in the atmosphere

  2. Sulfur dioxide (SO2) and nitrogen oxides (NOx) react in the atmosphere with water vapor (H2O in gas phase) forming mild solution of sulfuric acid & nitric acid (acid rain)

  3. These particles can travel long distances on wind currents

  4. Acid precipitation falls into lakes, rivers, & streams; killing organisms that live there
• Effects of acid precipitation

  • Drop pH of soil
  • Nutrients decrease
  • Releases aluminum & other toxic metals
• Effects of acid precipitation on plants

  • Soil changes cause root damage
  • Clogged openings on the surfaces of plants
• Transport & dispersion of air pollutants

  1. Wind is one of the major ways that air pollution can be spread

  2. Wind speed can greatly affect the pollutant concentration in a local area

  3. The higher the wind speed, the lower the pollutant concentration

  4. Wind dilutes pollutants and rapidly disperses them throughout the immediate area
• Atmospheric stability


  • Unstable atmospheric conditions result in a vertical mixing, thereby promoting dispersal of polluted air
  • Stable atmospheric conditions usually occur when warm air is above cool air and the mixing depth is significantly restricted
  • Temperature inversion can prevent the rise and dispersal of pollutants from the lower layers of the atmosphere and cause localized air pollution problem
• Temperature inversion


  When the air above is warmer than the air below it
• Problems with acid precipitation control: Pollutants are often released in an area far away from the area where acid precipitation falls
• Air Quality Index (AQI)


  A communication device to convey to the general public air quality conditions in a standard framework