Unit Seven: Atmospheric Pollution

7.1 Introduction to Air Pollution

• Air Pollutants:

  • Primary Pollutants: Emitted directly into the atmosphere.

  • Carbon Monoxide (CO)

  • Nitrogen Oxides (NOX)

  • Sulfur Oxides (SOX)

  • Particulate Matter (PM2.5, PM10)

  • Lead (Pb)

  • Volatile Organic Compounds (VOCs): Includes Hydrocarbons (HCs) such as formaldehyde.

• Secondary Pollutants: Formed from primary pollutants through chemical reactions.

  • Nitric Acid:

  • Reaction: $ext{NOX} + ext{H}<em>2 ext{O} ightarrow ext{HNO}</em>3$

  • Sulfuric Acid:

  • Reaction: $ext{SOX} + ext{H}<em>2 ext{O} ightarrow ext{H}</em>2 ext{SO}_4$

  • Ozone:

  • Reaction: $ext{NOX} + ext{VOCs} + ext{Sunlight} <br>ightarrow ext{O}_3$

• Six Criteria Pollutants (deemed most harmful by the EPA in 1970):

  • Sulfur Dioxide

  • Particulate Matter

  • Lead

  • Ozone

  • Nitrogen Oxide

  • Carbon Monoxide

  • Acronym: SPLONC

• Health Impacts of Lead Exposure:

  • Children:

  • Anemia

  • Behavioral disorders

  • Lowered IQ

  • Learning disabilities

  • Nerve damage

  • Adults:

  • Hypertension

  • Cardiovascular disease

• Fossil Fuel Combustion: Release various pollutants.

  • Combustion Products:

  • Carbon Dioxide (CO2)

  • Sulfur Oxides (SOX)

  • Particulate Matter (PM)

  • Lead (Pb)

• Clean Air Act:

  • A federal law regulating air pollutants, including lead and SOX.

7.2 Photochemical Smog

• Volatile Organic Compounds (VOCs):

  • Definition: Compounds that easily vaporize at room temperature.

  • Examples:

  • Anthropogenic: Formaldehyde, gasoline

  • Natural: Trees, plant oils

• Formation of Photochemical Smog (Ground-Level Ozone):

  • Sources: Urban areas with many cars

  • Primary Pollutants:

  • Nitrogen oxides

  • VOCs

  • Conditions for Formation:

  • Sunlight

  • Heat

  • Secondary Pollutants:

  • Ozone

  • Peroxyacyl Nitrates (PANS)

• Ozone Peaks:

  • Produced early in the day during rush hour from NO and VOCs.

  • Peaks in the afternoons and summers due to sunlight.

• Combating Photochemical Smog:

  • Regulating NOX and VOC emissions during combustion.

  • Catalytic Converters:

  • Convert NO into O2 and N2.

  • Reactions reduce CO and hydrocarbons to CO2 and H2O.

  • Tips to Reduce VOCs:

  • Pump gas at night.

• Health Effects:

  • Respiratory issues (asthma, bronchitis, emphysema).

  • Eye irritation, damage to plants.

7.3 Thermal Inversion

• Definition: A meteorological event where warmer air traps colder air close to the ground, leading to increased pollution concentration.

  • Causes: Photochemical smog and particulate matter accumulation.

• Geographical Influences:

  • Valleys

  • Nearby mountain ranges

  • Coastal winds

7.4 Atmospheric CO2 and Particulates

• Anthropogenic CO2 Sources:

  • Biomass burning (wood, crops).

  • Fossil fuel emissions (factories, vehicles).

• Particulate Matter Sources:

  • Agricultural activities (tillage, crop rotation).

  • Construction sites, fossil fuels, vehicle exhaust.

• Natural CO2 Sources:

  • Respiration

  • Decomposition

  • Volcanic eruptions

  • Wildfires

• Carbon Cycle:

  • Fast Carbon: Carbon that switches forms rapidly (months to years), such as trees growing and dying.

  • Fossil Carbon: Locked away for millions of years in the carbon cycle; contributes to climate change upon combustion.

7.5 Indoor Air Pollutants

• Natural Sources:

  • Mold, Dust, Radon

• Human-Made Sources:

  • Asbestos, combustion smoke, VOCs

• Carbon Monoxide (CO):

  • Colorless, odorless, tasteless gas produced by various burning processes.

  • Health Risks: CO binds more effectively to hemoglobin than oxygen, leading to suffocation.

• Sources of Carbon Monoxide in Homes:

  • Running cars in garages, clogged chimneys, gas stoves, and more.

• Radon:

  • Colorless, odorless gas from uranium decay, linked to lung cancer.

  • Reduction Measures: Sealing cracks in buildings.

• VOCs:

  • Volatile organic compounds that can cause headaches. Found in products like paints, adhesives, and cleaning materials.

• Asbestos:

  • Used in insulation materials; can cause serious lung diseases when inhaled.

7.6 Reduction of Air Pollutants

• Methods of Reducing Air Pollution:

  • Vapor Recovery Nozzle: Prevents VOCs from escaping during gas pumping.

  • Catalytic Converters: Convert harmful gases into less toxic substances.

  • Scrubbers: Remove pollutants from smokestacks using filters or chemical solutions.

  • Electrostatic Precipitators: Use charged plates to attract and remove particulates.

  • Trade-offs: Managing toxic waste from scrubbers is critical to prevent environmental harm.

  • Alternative Fuels Supported by the Clean Air Act:

  • Natural Gas, Propane, Ethanol, Biofuels, Electric Vehicles

7.7 Acid Rain

• Definition of pH:

  • Symbol for potential Hydrogen, calculated as - log of H+ ion concentration.

• Acid Rain Causes:

  • Formed from NOX and SOX reacting with water.

  • Sources: Vehicle exhaust, coal burning.

• Effects of Acid Rain:

  • Damages trees, lowers pH of water, affects aquatic life, and erodes structures.

  • Can lead to soil and water acidification, harming ecosystems.

  • Natural Neutralizer: Limestone can help reduce acidity.

7.8 Noise Pollution

• Definition: Sound levels that can cause stress and hearing loss.

• Sources of Noise Pollution:

  • Traffic, construction activities

• Health Impacts:

  • Hearing impairment, hypertension, sleep disturbances, decreased academic performance.

• Decibel Scale:

  • Measures sound intensity; exposure above 85 dBA can lead to hearing loss.

• Effects on Animals:

  • Interference in hunting and mating calls, altered migratory habits, reducing food access.