Unit 7: Atmospheric Pollution 

Essential Skills

You should be able to understand and describe:

• 7.1 Identify the sources and effects of air pollutants

  1. Coal combustion releases air pollutants including carbon dioxide, sulfur dioxide, toxic metals, and particulates.

  2. The combustion of fossil fuels releases nitrogen oxides into the atmosphere. They lead to the production of ozone, formation of photochemical smog, and convert to nitric acid in the atmosphere, causing acid rain. Other pollutants produced by fossil fuel combustion include carbon monoxide, hydrocarbons, and particulate matter.

  3. Air quality can be affected through the release of sulfur dioxide during the burning of fossil fuels, mainly diesel fuels.

  4. Through the Clean Air Act, the Environmental Protection Agency (EPA) regulated the use of lead, particularly in fuels, which dramatically decreased the amount of lead in the atmosphere.

  5. Air pollutants can be primary or secondary pollutants. 

• 7.2 Explain the causes and effects of photochemical smog and methods to reduce it

  1. Photochemical smog is formed when nitrogen oxides and volatile organic hydrocarbons (VOCs) react with heat and sunlight to produce a variety of pollutants

  2. Many environmental factors affect the formation of photochemical smog. 

  3. Nitrogen oxide is produced early in the day. Ozone concentrations peak in the afternoon and are higher in the summer because ozone is produced by chemical reactions between oxygen and sunlight.

  4. Volatile Organic Compounds (VOCs), such as formaldehyde and gasoline, evaporate or sublimate at room temperature. Trees are a natural source of VOCs.

  5. Photochemical smog often forms in urban areas because of the large number of motor vehicles there. 

  6. Photochemical smog can be reduced through the reduction of NOx and VOCs.  

  7. Photochemical smog can harm human health in several ways, including causing respiratory problems and eye irritation.  

• 7.3 Describe thermal inversion and its relationship to pollution

  1. During a thermal inversion, the normal temperature gradient in the atmosphere is altered as the air temperature at the Earth’s surface is cooler than the air at higher altitudes. 

  2. Thermal inversion traps pollution close to the ground, especially smog and particulates. 

• 7.4 Describe natural sources of CO₂ and particulates

  1. CO₂ appears naturally in the atmosphere from sources such as respiration, decomposition, and volcanic eruptions. 

  2. There are a variety of natural sources of particulate matter.  

• 7.5 Identify indoor air pollutants and their effects 

  1. CO is an indoor air pollutant that is classified as an asphyxiant. 

  2. Indoor air pollutants that are classified as particulates include asbestos, dust, and smoke

  3. Indoor air pollutants can come from natural sources, anthropogenic (man made) sources, and combustion.  

  4. Common natural sources indoor air pollutants include radon, mold, and dust.  

  5. Common anthropogenic indoor air pollutants include insulation, VOCs from furniture, paneling, and carpets; formaldehyde from building materials, furniture, upholstery, carpeting, and lead from paints. 

  6. Common combustion air pollutants include CO, NO_x, SO₂, particulates, and tobacco smoke. 

  7. Radon-222 is a naturally occurring radioactive gas that is produced by the decay of uranium found in some rocks and soils. 

  8. Radon gas can infiltrate homes as it moves up through the soil and enters homes via the basement or cracks in walls or foundations.  It is also dissolved in groundwater that enters homes through a well.  

  9. Exposure to radon gas can lead to radon-induced lung cancer, which is the second leading cause of lung cancer in America. 

• 7.6 Explain how air pollutants can be reduced at the source

  1. Methods to reduce air pollutants include regulatory practices, conservation practices, and alternative fuels. 

  2. A vapor recovery nozzle is an air pollution control device on a gasoline pump that prevents fumes from escaping into the atmosphere when fueling a vehicle. 

  3. A catalytic converter is an air pollution control device for internal combustion engines that convert pollutants (CO, NO_x, hydrocarbons) in exhaust into less harmful molecules (CO₂, N₂, O₂, and H₂O). 

  4. Wet and dry scrubbers are air pollution control devices that remove particulates and/or gases from industrial exhaust streams. 

  5. Methods to reduce air pollution from coal-burning power plants include scrubbers and electrostatic precipitators. 

• 7.7 Describe acid deposition and its environmental impacts  

  1. Acid deposition is due to NOx and SOx from anthropogenic and natural sources in the atmosphere. 

  2. NOx that causes acid deposition come from vehicles and coal-burning power plants.  SO₂ that cause acid deposition come from coal-burning power plants. 

  3. Acid deposition mainly affects communities that are downwind from coal-burning power plants. 

  4. Acid rain and deposition can lead to the acidification of soils and bodies of water and corrosion of man-made structures. 

  5. Regional differences in soils and bedrock affect the impact that acid deposition has on the region- such as limestone bedrock’s ability to neutralize the effect of acid rain on lakes/ponds. 

• 7.8 Describe human activities that result in noise pollution and its effects

  1. Noise pollution is sound at levels high enough to cause physiological stress & hearing loss. 

  2. Sources of noise pollution in urban areas include transportation, construction, domestic and industrial activity. 

  3. Some effects of noise pollution on animals in ecological systems include stress, masking of sounds used to communicate/hunt, damaged hearing, and causing changes to migratory routes. 

Particulate Matter

Lead

Nitrogen Oxides (NOx)

Sulfur Dioxide (SO₂)

Volatile Organic Compounds (VOCs)

Ozone

Photochemical Oxidants

Radon

Mold

Dust

Asbestos

Carbon Monoxide (CO)

Methane (CH₄)

Carbon Dioxide (CO₂)

Clean Air Act

Noise Pollution

Primary Air Pollutant

Secondary Air Pollutant

Photochemical Smog

Temperature Inversion

Electrostatic Precipitator

Scrubbers

Catalytic Converters

Vapor Recovery Nozzle

Fluidized Bed Combustion

Limestone

Acid Deposition

Sulfuric Acid

Nitric Acid