Unit 7 Review: Air Pollution

Intro to Air Pollution

  • Key pollutants, abbreviations, and names.
  • Background material for scoring well on the test.

Primary and Secondary Pollutants

  • Primary Pollutants: Directly emitted from a source.
    • Example: NO2 (nitrogen dioxide) from a car.
  • Secondary Pollutants: Formed in the atmosphere through chemical reactions.
    • Example: Ozone (O3) formed from NO2.

Key Pollutants

  • Know both abbreviations and chemical names.

SOx (Sulfur Oxides)

  • Mainly from power plant coal burning.
  • Example: Sulfur dioxide (SO2).

NOx (Nitrogen Oxides)

  • From coal burning power plants and cars.
  • Example: Nitrogen dioxide (NO2).

Carbon Dioxide (CO2)

  • Naturally occurring from respiration, decomposition, and volcanoes.
  • Can cause climate change issues due to being a greenhouse gas.

Toxic Metals

  • Released mainly through combustion of coal.
  • Examples: Lead (Pb) and mercury (Hg), both toxic to the nervous system.

Particulate Matter (PM)

  • From combustion (coal, cigarette smoke, wood fires).

Clean Air Act (CAA)

  • A United States federal law to regulate six major air pollutants.
  • Helped regulate lead in gasoline.

Photochemical Smog

  • Forms when NOx chemicals react with sunlight and VOCs (volatile organic compounds).
  • Smog is just another term for photochemical smog

Formation Process

  1. NOx Formation: Occurs early in the day, mainly from car traffic (e.g., rush hour).
  2. Ozone Creation: NOx reacts with sunlight to create ozone (O3).
  3. Smog Creation: Ozone reacts with VOCs to create photochemical smog.

VOCs (Volatile Organic Compounds)

  • Chemicals found in gasoline, formaldehyde, varnishes, paint, nail polish, perfume, and tree sap.
  • Evaporate easily at room temperature and often have strong smells.

Environmental Factors

  • Cities in valleys or near mountains tend to have worse smog problems due to settling.

Chemical Reactions

  1. NO2+sunlight  →  NO+ONO_2 + sunlight \;\rightarrow \; NO + O (Nitrogen dioxide reacts with sunlight to form nitric oxide and an oxygen radical)
  2. O+O<em>2  →  O</em>3O + O<em>2 \;\rightarrow \; O</em>3 (Oxygen radical binds with oxygen gas to create ozone)
  3. O<em>3+NO  →  O</em>2+NO2O<em>3 + NO \;\rightarrow \; O</em>2 + NO_2 (Ozone reacts with nitric oxide to revert to oxygen gas and nitrogen dioxide - normal pattern of ozone destruction)
  4. VOCs bind with NO, creating photochemical oxidants.
  5. O3 combines with photochemical oxidants which results in smog.

Thermal Inversions

  • Normal Conditions: Air is warmer near the surface and gets colder further out.
  • Thermal Inversion: Warm air traps cold air close to the Earth's surface.
  • Pollution (smog, particulates) gets trapped beneath the warm air.

The Great Smog of London

  • Example of a devastating thermal inversion in the mid-1900s.
  • Coal burning released particulate matter and NOx/SOx chemicals, which were trapped.
  • Estimated 12,000 deaths occurred due to the smog's effects.

Acid Deposition

  • Can be acid rain (wet deposition) or dry deposition (particulate acid).
  • Primarily due to nitrogen oxides (NOx) and sulfur oxides (SOx).

Formation Process

  1. SOx and NOx chemicals are released into the atmosphere.
  2. They mix with water vapor.
  3. Secondary pollutants (nitric acid and sulfuric acid) are created.
  4. Acid deposition occurs, potentially affecting areas downwind from the source.

Effects

  • Irritation to skin, lungs, and eyes.
  • Acidification of soils and water bodies.
  • Damage to forests and ecosystems.
  • Damage to ancient buildings and statuary (e.g., marble structures).
  • Leaching of toxic metals from the ground.
  • Limestone in soils can help neutralize acid.

Indoor Air Pollutants

  • Come from natural, man-made, and combustion sources.

Natural Sources

  • Radon (radioactive material from uranium decay).
  • Mold and dust particulates.
  • Asbestos (construction material with harmful fibers).

Man-Made Sources

  • Insulation.
  • VOCs from furniture, paneling, carpets, formaldehyde, and lead in paint.

Combustion Sources

  • Burning wood in fireplaces releases carbon monoxide (CO), NOx, SOx, and particulate matter.
  • Combustion of tobacco and cigarettes.

Radon

  • Comes from uranium decaying into radon-222 (a gas).
  • Enters homes through cracks in the foundation, especially in basements.
  • Can cause lung damage and is the second leading cause of lung cancer in the United States.

Noise Pollution

  • High levels of noise can cause hearing loss and physiological stress.

Sources

  • Urban transportation, construction, domestic activity, and industrial activity.

Effects on Humans

  • Anxiety, poor concentration, loss of sleep, stress, and general effects on physical health.

Effects on Animals

  • Altered behavior.
  • Difficulty communicating or finding a mate.
  • Struggles for animals using echolocation.
  • Effects on marine animals from boat motor noise, sonar, and offshore drilling.

Methods for Reduction of Air Pollutants

  • Catalytic converters in vehicles to convert NOx and carbon monoxide into less harmful chemicals.
  • Vapor recovery nozzles on gasoline pumps to capture fumes.
  • Scrubbers to remove particulates through water (used in coal-fired power plants).
  • Electrostatic precipitators to remove particulates using static (used in power plant smokestacks).
  • Reduce fossil fuel use through conservation practices.
  • Regulatory methods such as the Clean Air Act to regulate major air pollutants.