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Air Pollution. Chapter 18-19. There is no place on Earth that isn’t affected by air pollution…. Air pollution : presence of chemicals in the atmosphere in concentrations high enough to harm organisms, ecosystems, human-made materials or to alter climate Ranges from annoying to lethal

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air pollution

Air Pollution

Chapter 18-19

There is no place on Earth that isn’t affected by air pollution…


Air pollution: presence of chemicals in the atmosphere in concentrations high enough to harm organisms, ecosystems, human-made materials or to alter climate

    • Ranges from annoying to lethal
    • Refers to pollution in the troposphere
    • Natural sources
      • Dust, wildfires, volcanic eruptions
    • Human sources
      • Industrialized and urban areas
      • fossil fuel burning

Primary Pollutants: chemicals or substances emitted directly into the air from natural sources and human activities

    • Carbon monoxide, carbon dioxide, sulfur dioxide and nitric oxides; particulate matter; VOCs (natural sources—terpenes, plant fragrance)
  • Secondary Pollutants: primary pollutants react with one another and natural components to form harmful chemicals, often in the presence of sunlight and water
    • Ozone, acid deposition (sulfates and nitrates)
  • To determine and monitor Air Quality, the EPA actively monitors…
    • carbon monoxide
    • ozone
    • lead
    • nitrogen dioxide
    • particulate matter (also known as particle pollution)
    • sulfur dioxide
major air pollutants
Major Air Pollutants
  • Carbon Oxides
    • Carbon Dioxide: from fossil fuel burning (major pollutant); is a greenhouse gas that impacts climate; required for photosynthesis; colorless and odorless
    • Carbon Monoxide: from combustion of carbon (exhaust, forest burning, fossil fuels, tobacco smoke); Limits oxygen binding in hemoglobin which can result in heart attack, asthma, emphysema, nausea and death; colorless and odorless—dangerous indoor air pollutant

Nitrogen Oxides (NOx) and Nitric Acid

    • Nitric Oxide (NO): combustion in cars, coal burning, lightning, part of soil and water (nitrogen cycle); colorless and odorless
    • Nitrogen Dioxide (NO2): nitrogen monoxide reacts with oxygen (NO2); reacts with water to form nitric acid and nitrate salts (acid deposition); forms photochemical smog (with sunlight); helps in the formation of tropospheric ozone; stinky, reddish-brown gas
    • Nitrous Oxide (N2O): greenhouse gas from fertilizers and animal wastes, also fossil fuel burning

** all are irritants to eyes, nose and throat, aggravate asthma and bronchitis; suppress plant growth and harm aquatic life


Sulfur Dioxide and Sulfuric Acid

  • Sulfur Dioxide (SO2): 1/3 comes from natural sources (sulfur cycle), the rest is anthropogenic (coal burning, oil refining, smelting); corrosive gas
  • Sulfuric Acid: forms when SO2 reacts with water in the atmosphere, then falls as acid deposition (acid rain).

**Aggravate breathing problems (respiratory irritant), decrease plant growth, corrosive



    • Suspended particulate matter (solid particles and liquid droplets); particles smaller than 10 micrometers are regulated by the EPA as air pollution (not filtered by nose/throat)
      • Outdoor: dust, wildfires, sea salt, coal/oil burning, cars (especially diesel), construction; road dust, rock crushing; volcanic activity
      • Indoor: cigarettes, burning inside (developing countries)

**Aggravate eyes, nose, and throat, damage lungs, asthma/bronchitis, genetic mutations, and cancer (premature death)

**Reduces the amount of incoming solar radiation (weather)


Ozone (O3)

  • Secondary pollutant that contributes to photochemical smog
    • Tropospheric ozone bad. Stratospheric ozone good.
  • Ozone thinning is the stratosphere…which increases the amount of UV radiation that reaches us
    • Damages living tissue
    • Results from release of CFCs and other Freons…from coolants and aerosols
    • Montreal Protocol—Limit these chemicals in manufactured products

**Coughing and breathing problems (asthma and emphysema), lung/heart disease, irritant; damaging to rubber and plastic


Volatile Organic Compounds (VOCs)

  • Organic compounds (hydrocarbons) that exist as gases in the atmosphere
    • Give off strong aroma (paint, perfume, gasoline, flatulence)
    • Help in formation of smog, not all hazardous…but some have the potential to be harmful
    • Ex. Methane—greenhouse gas from landfills, cows, decomposition, oil and gas burning/refining
    • Others include benzene, industrial solvents, gas and plastics

Mercury: found in coal and oil, released from fossil fuel burning, can settle out into water. Seeing bioaccumulation into food chains.

    • Toxin for central nervous system
  • Lead: occurs naturally in rocks and soils, also present in fuels and paints.
    • Toxic to central nervous system (children), affects learning, concentration, and intelligence
factors affecting air pollution
Factors Affecting Air Pollution
  • Increase air pollution
    • Buildings break up wind
    • Hills/mountains decrease air flow
    • High temperature increases reactions
    • Emissions of VOCs increase smog formation
    • Temperature inversions (warm air over cool)
  • Decrease air pollution
    • Heavy particles settle out of air
    • Rain/snow cleanse air
    • Salty sea spray washes air
    • Winds mix air
    • Pollutants removed by reactions
acid deposition
Acid Deposition
  • Air pollutants mix with water in air to form acidic precipitation (acid rain)
    • Nitrogen and sulfur oxides—form nitric and sulfuric acid (pH ~5)
  • Has been occurring since the Industrial Revolution
  • Usually a regional problem…downwind of coal burning facilities
  • Pollutants are moved by winds
  • Damages statues, buildings; causes respiratory diseases, leach toxic metals into the environment from rocks; harmful to aquatic ecosystems, hurts agriculture, and weakens forests and plants
  • Reduced by limiting emissions of pollutants (alternative energy sources)
  • Industrial
    • Unhealthy mix of sulfur dioxide and sulfuric acid and solid particles
    • Comes from coal burning in large quantities
    • Rarely a problem in developed countries…big problem in developing (China)
    • Sulfur dioxide and sulfates mostly; “grey smog”
  • Photochemical
    • Mixture of primary and secondary pollutants formed under the influence of UV radiation
    • “brown smog”—made up mostly of ozone
indoor vs outdoor air pollution
Indoor vs. Outdoor Air Pollution
  • Indoor Air Pollution from burning wood, charcoal in open fires or poorly designed stoves; cigarette smoke
    • Carbon monoxide and particulates
  • Impacts high poverty/poor countries
  • Sources include:
    • Tobacco smoke
    • formaldehyde
    • Radon gas
    • Fine particulates
    • Pesticide residues
    • Lead
    • Organic solvents
    • Living organisms (mites, roaches)
    • Mold and fungal spores
radon gas
Radon Gas
  • Colorless, odorless radioactive gas that is produced by the radioactive decay of uranium-238 (from underground rock)
    • Only problematic in certain areas of the country
  • Can seep through cracks in the foundation and build up to harmful levels in air, or seep into groundwater
  • Damages lung tissue and lead to cancer (second leading cause of lung cancer)
    • Radon-222 decays to Polonium-210 (harmful/carcinogen)
dealing with air pollution
Dealing with Air Pollution
  • Clean Air Act: set aside air pollution regulations
    • EPA monitors pollutants and sets standards for emissions
  • EPA's mission is to protect human health and the environment. To achieve this mission, EPA implements a variety of programs under the Clean Air Act that focus on:
  • reducing outdoor, or ambient, concentrations of air pollutants that cause smog, haze, acid rain, and other problems;
  • reducing emissions of toxic air pollutants that are known to, or are suspected of, causing cancer or other serious health effects; and
  • phasing out production and use of chemicals that destroy stratospheric ozone.
  • These pollutants come from stationary sources (like chemical plants, gas stations, and powerplants) and mobile sources (like cars, trucks, and planes).
  • Buy and sell pollution allotments
  • Prevention in best solution!
    • Improve fuel efficiency standards
    • Alternative energy sources
    • Educate public about pollution
air quality index
Air Quality Index
  • National Ambient Air Quality Standards
    • EPA sets standards for pollutants harmful to humans or the environment (clean air act)
    • Primary standards protect public health
    • Secondary standards protect public welfare
    • Carbon Monoxide, Lead, Particulates, Ozone, Nitrogen Dioxide and Sulfur Dioxide