AP Environmental Science - Air and Noise Pollution Notes

7.1 Introduction to Air Pollution

• Air pollution is contamination of the indoor or outdoor environment by chemical, physical, or biological agents that modifies the atmosphere's natural characteristics.
• Two major sources:
  • Natural: Volcanic eruptions, wildfires, dust storms.
  • Human: Industrial emissions, vehicle exhaust, agriculture, residential heating.
• Primary Pollutants:
  • CO (Carbon Monoxide)
  • $NO_x$ (Nitrogen Oxides)
  • $SO_2$ (Sulfur Dioxide)
  • Particulate Matter ($PM<em>{10}$, PM{2.5})
  • Volatile Organic Compounds (VOCs)
• Secondary Pollutants:
  • Ozone ($O<em>3$) (from VOCs + $NO</em>x$ under sunlight)
• Coal Combustion:
  • Releases more air pollutants than other Fossil Fuels (FFs); ~35% of global electricity
  • Releases CO, $CO<em>2$, $SO</em>2$, NO, toxic metals (mercury, arsenic, lead), and PM (often carries the toxic metals).
  • Impacts of $SO_x$:
    • Respiratory irritant (inflammation of bronchioles, lungs), worsens asthma & bronchitis
    • Sulfur aerosols (suspended sulfate particles) block incoming sun, reducing visibility & photosynthesis
    • Forms sulfurous (grey) smog
    • Combines with water & $O_2$ in the atmosphere to form sulfuric acid → acid precipitation.
• FRQ:
  • If the experiment were repeated with natural gas, it would likely result in lower $NO_2$ production compared to coal combustion due to cleaner burning and lower flame temperature.

7.2 Photochemical Smog

• Precursors & Conditions:
  • Precursors: $NO_2$
    • Broken by sunlight into NO + O (free O + $O<em>2$ → $O</em>3$)
    • Volatile organic compounds (hydrocarbons) that bind with NO & form photochemical oxidants
    • $O<em>3$ Forms when $NO</em>2$ is broken by sunlight, and free O binds to $O_2$
  • Conditions:
    • Sunlight: Drives $O<em>3$ formation by breaking down $NO</em>2$ → NO + O; then free O atom binds to $O_2$
    • Warmth: Hotter atm. Temp. speeds $O_3$ formation, evaporation of VOCs, and thus smog formation
• Factors That Increase Smog Formation:
  • More traffic → More $NO_2$
  • Hotter temps due to low albedo of blacktop
  • More VOCs due to gas stations and factories
  • More electricity demand; more NO emissions from nearby power plants
• Impacts and Reduction of Smog:
  • Smog is dirty air caused by pollution from cars, factories, and burning fuels.
  • It can cause breathing problems, hurt the environment, and reduce visibility.
  • We can reduce smog by using clean energy, driving less, and following environmental rules.
• FRQ:
  • Ozone concentration increases during the day as sunlight breaks down $NO<em>2$, forming ozone, and decreases at night when there's less sunlight and more $NO</em>2$, which removes ozone from the air.

7.3 Thermal Inversion

• Definition:
  • A thermal inversion occurs when a layer of warm air overlays cooler air near the earth's surface, preventing the normal upward movement of air.
• Normal Conditions:
  • Warm air rises, allowing pollutants to disperse into the upper atmosphere.
• Inversion Conditions:
  • During a thermal inversion, the warm air layer acts as a cap, trapping pollutants close to the ground.
• Common Locations:
  • Valleys and areas surrounded by mountains are particularly susceptible due to limited air circulation.
• Causes:
  • Radiational cooling: Clear nights allow the ground to cool rapidly, chilling the air above.
  • Topography: Geological features like valleys can trap cold air.
  • Weather patterns: High-pressure systems can lead to stagnant air masses.
• Environmental Impact:
  • Air quality degradation: Pollutants such as nitrogen oxide sulfur dioxide.
  • Health risks: Increased respiratory issues, especially among vulnerable populations.
• Mitigation Strategies:
  • Emission controls: Implementing stricter regulations on industrial emissions and vehicle exhaust.
  • Urban planning: Designing cities to enhance airflow and reduce pollutant.
  • Public awareness: Educating communities about the dangers of thermal inversion.
• Real-World Examples:
  • Los Angeles, USA: Frequent inversions due to its basin topography and high vehicle emissions.
  • Mexico City, Mexico: Surrounded by mountains, leading to regular inversion events and smog issues.

7.4 Atmospheric $CO_2$ and Particulates

• Natural Sources:
  • $CO_2$: Emitted through processes like cellular respiration, volcanic eruptions, and decomposition of organic matter.
  • Particulates: Generated by wildfires, volcanic ash, sea spray, and pollen dispersal.
• Anthropomorphic (Human-Made) Sources:
  • $CO_2$: Produced from the combustion of fossil fuels (coal, oil, natural gas) in transportation, electricity generation, and industry.
  • Particulates: Emitted from industrial activities, vehicle exhaust, construction sites, and burning biomass.
• Environmental Impacts:
  • $CO<em>2$ as a greenhouse gas: Elevated $CO</em>2$ levels contribute to global warming and climate change, affecting ecosystems and weather patterns.
  • Particulates: Can reduce sunlight penetration, affecting photosynthesis in plants and contributing to the formation of smog.
• Health Impacts:
  • Fine particulate matter can penetrate deep into the lungs of the bloodstream, leading to respiratory and cardiovascular issues.
  • Vulnerable populations: Children, the elderly, and individuals with pre-existing health conditions are particularly at risk.
• Mitigation Strategies and Policy Measures:
  • Technological Solutions:
    • Emission controls: Implementation of filters and scrubbers in industrial settings to reduce particulate emissions.
    • Renewable Energy: Transitioning to solar, wind, and hydroelectric power to decrease $CO_2$ emissions.
  • Policy Measures:
    • Regulations: Establishment of air quality standards and emission limits by governments and international bodies.
    • Public awareness: Educational campaigns to inform the public about the sources and impacts of air pollution.
  • Community Actions:
    • Urban planning: Designing cities to reduce traffic congestion and promote public transportation.
    • Green spaces: Increasing vegetation in urban areas to absorb $CO_2$ and filter particulates.

7.5 Indoor Air Pollutants

• Developing Countries:

  • Use wood, charcoal, and manure for cooking (biomass).
  • Smoke releases CO, PM, $NO_x$, and VOCs.
  • Often no good ventilation = very dangerous.
  • Causes ~3.5–4.3 million deaths each year.

• Developed Countries:

  • Use gas, oil, coal (cleaner, commercial fuels).
  • Pollution comes from chemicals in products (furniture, cleaning).
  • Better stoves and good ventilation.

• Main Indoor Air Pollutants:

  • PM (Particulate Matter):
    • Comes from smoke, dust, asbestos.
    • Asbestos is dangerous if disturbed. Causes lung cancer.
  • CO (Carbon Monoxide):
    • Made from incomplete burning.
    • No color, no smell. Can kill.
    • Comes from gas stoves or indoor fires.
  • VOCs:
    • From glue, paint, cleaning products.
    • Formaldehyde = strong smell (carpets, furniture).
    • Irritates eyes and lungs.

• Other Dangerous Pollutants:

  • Radon Gas:
    • Comes from rocks underground.
    • Enters home through cracks.
    • Causes lung cancer.
  • Lead:
    • In old paint (before 1978).
    • Kids can eat paint or breathe dust.
    • Also in old pipes.
    • Damages the brain. Must be removed.
  • Mold and Dust:
    • Mold grows in wet, dark places.
    • Dust in the air can hurt lungs.
    • Clean mold and fix water leaks.

• FRQ:

  • 1-Why is cooking with wood or charcoal dangerous in developing countries?

  • 2-What can cause lung cancer in developed countries and how?

  • 1-Cooking with wood or charcoal indoors releases smoke and toxic fumes, causing respiratory diseases due to poor ventilation.

  • 2-In developed countries, lung cancer can be caused by smoking or air pollution, damaging lung cells over time.

7.6: Air Pollution Reduction

• Air pollution is harmful to people and the planet.
• Reducing air pollution helps keep the air clean and safe.
• Government Actions:
  • The Clean Air Act is a law that sets rules to keep the air clean.
  • It limits how much pollution companies, cars, and schools can release.
  • It encourages using cleaner fuels and better technology.
• Technology to Reduce Pollution:
  • Catalytic converters clean car exhaust.
  • Scrubbers remove dirty gases from factories.
  • Electrostatic precipitators catch tiny dust particles before they enter the air.
• What People Can Do:
  • Drive less, use cleaner vehicles (like electric cars).
  • Save electricity and energy at home.
  • Support clean air laws and policies.
• FRQ:
  • The Obama CAFE rules helped cut NOx pollution by making cars use less fuel. Figure 1 shows fuel economy going up to 45.5 mpg by 2025, meaning cleaner air in cities.

7.7 Acid Rain

• Acid rain is rain (or any precipitation) that is more acidic than normal because it contains sulfur dioxide ($SO<em>2$) and nitrogen oxides ($NO</em>x$) from pollution.
• Causes:
  • Burning of fossil fuels (like coal, oil, gas)
  • Industrial processes
  • Vehicle emissions
• Effects of Acid Rain:
  • On the Environment:
    • Damages forests by weakening trees.
    • Makes lakes and rivers too acidic for fish and wildlife.
  • On Buildings:
    • Erodes stone and metal structures (especially statues and old buildings).
  • On Humans:
    • Indirect effects (damaged water sources, food chain disruption).
• Solutions:
  • Use cleaner energy sources (solar, wind, natural gas).
  • Install scrubbers on factories to clean emissions.
  • Follow environmental laws like the Clean Air Act.
• What You Can Do:
  • Save energy, drive less, support clean energy.

7.8: Noise Pollution

• Noise pollution refers to unwanted or harmful sounds that disrupt the environment.
• Common sources include transportation, construction, and industrial activities.
• Understanding noise pollution is crucial for protecting human health and wildlife.
• Sources of Noise Pollution:
  • Transportation: Cars, trains, airplanes.
  • Construction: Jackhammers, heavy machinery.
  • Industry: Factories, power plants.
  • Urban areas often have higher noise levels due to these activities.
• Effects on Humans and Animals:
  • Humans:
    • Hearing loss from prolonged exposure.
    • Increased stress, anxiety, and sleep disturbances.
    • Potential for high blood pressure and heart issues.
  • Animals:
    • Disrupted communication and mating calls.
    • Altered migration patterns.
• Solutions and Regulations:
  • Regulations:
    • Noise Control Act of 1972: Allows the EPA to set noise standards.
    • Occupational Safety and Health Administration (OSHA): Sets workplace noise limits.
  • Solutions:
    • Implementing sound barriers near highways.
    • Using quieter machinery and vehicles.
    • Urban planning to separate residential areas from noisy industries.
• FRQ:
  • The author says whales might adapt because they can change their behavior faster than their bodies. Some whales have already started avoiding loud areas or making louder calls to be heard. Thus being able to adapt to the increased levels of aquatic noise pollution because their behavior is more adaptable than their physical bodies.