LZ

APES- Unit 7

Air Pollution Basics

  • Types of Air Pollutants

    • Air Pollutants vs. Greenhouse Gases (GHGs): Different kinds of pollutants that affect air quality and contribute to climate change.

    • Coal Combustion: A major source of air pollutants, particularly sulfur dioxide (SO2) and nitrogen oxides (NOx).

    • Nitrogen Oxide (NOx): Includes both NO and NO2; contributes to smog and respiratory issues.

    • Lead (Pb): Historically added to gasoline, now being phased out due to health risks.

Clean Air Act (1970)

  • Established by the EPA to regulate air pollutants.

    • Identified 6 criteria pollutants that must have acceptable limits.

    • CO2 is not included in these 6 pollutants despite its role as a GHG and environmental impact.

    • Primary focus: Public health and air quality (toxicity, visibility effects).

Primary vs. Secondary Pollutants

  • Primary Pollutants: Emitted directly from sources, e.g., NOx, CO, VOCs.

  • Secondary Pollutants: Formed through reactions in the atmosphere, e.g., tropospheric ozone formation from NOx and VOCs.

Impacts of Specific Pollutants

  • Sulfur Dioxide (SO2):

    • Respiratory irritant that contributes to acid rain.

    • Forms sulfuric acid when combined with atmospheric water.

  • Nitrogen Oxide (NOx):

    • Contributes to photochemical smog and respiratory problems.

  • Lead (Pb):

    • Removed from gasoline in 1974; vehicles require catalytic converters to lessen NOx and CO emissions.

Photochemical Smog Formation (7.2)

  • Normal Ozone (O3) Formation: Involves chemical reactions under sunlight.

  • Precursor Pollutants: NOx and VOCs, emitted from vehicles and industrial processes.

    • Emission increases during daytime; smog formation peaks in warmer temperatures.

Ozone Formation Process

  1. Morning traffic raises NO2 levels.

  2. Sunlight breaks down NO2 into NO and free oxygen (O).

  3. O combines with O2 to produce O3.

  4. At night, O3 reacts with NO to revert to NO2, leading to reduced daytime levels.

Impacts + Reduction of Smog

  • Environmental Effects: Reduced sunlight for photosynthesis; damage to plant stomata; respiratory issues in humans (asthma, bronchitis).

  • Economic Effects: Increased healthcare costs, lost productivity, and reduced agricultural yields.

  • Reduction Strategies:

    • Reduce vehicle numbers (carpooling, public transport).

    • Transition to renewable energy sources, e.g., solar and wind.

Urban Heat Island Effect

  • Urban areas experience higher temperatures due to materials like asphalt absorbing heat.

  • Less vegetation leads to decreased evapotranspiration, raising local air temperatures, and increasing smog.

Historical Events to Know

  • Donora, PA (1948): Steel mill pollution led to 20 deaths due to temperature inversions trapping smoke.

  • London Smog (1952): Cold weather combined with coal burning caused severe smog, resulting in 4,000 deaths.

Natural Sources of Air Pollution

  • CO2 and Particulate Matter (PM): From natural processes such as respiration, plant emissions, wildfires, and volcanic activity.

  • Respiration: All living organisms release CO2.

  • Volcanic Activity: Releases SO2, PM, NOx, affecting air quality.

PM10 vs. PM2.5

  • Particulate Matter (PM): Refers to airborne particles that can cause respiratory issues.

    • PM10: Larger particles (can be filtered by the nose).

    • PM2.5: Smaller particles (penetrate deep into lungs, associated with chronic diseases).

Indoor Air Pollutants

  • Developing Countries: Use of biomass fuels indoors leads to high CO, PM, and VOC emissions due to poor ventilation.

  • Developed Countries: Utilize commercial fuels, with major sources of indoor pollutants coming from household products and poor ventilation.

    • Lead: Historically contained in paints and pipes; poses neurological risks, especially to children.

Reducing Emissions

  • Laws and Regulations:

    • Clean Air Act enables EPA to set and enforce air quality standards.

    • Pollution Credits for companies performing below emissions standards.

    • Corporate Average Fuel Economy (CAFE) establishes efficiency standards for vehicles.

Strategies to Reduce Air Pollution

  • Promote increased use of public transport and renewable energy.

  • Implement vapor recovery nozzles to lower VOC emissions.

  • Use catalytic converters to convert harmful emissions (NOx and CO).

Acid Rain (7.9)

  • Primary Pollutants: SO2 and NOx are the main contributors to acid rain.

    • Formation: SO2/NOx react with atmospheric O2 and H2O to create nitric and sulfuric acid.

Environmental Effects

  • Acidification of soil and water reduces pH, affecting forest ecosystems and aquatic life.

  • High H+ concentrations can displace essential nutrients from soil, harming plant and animal life.

Urban Noise Pollution (7.10)

  • Sources: Construction, transportation, industrial activities, and domestic noise.

  • Effects on Wildlife: Disrupted communication and migration, hearing damage in animals, and physiological stress.

  • Aquatic Pollution: Marine life, especially whales, face challenges due to noise disrupting communication and migration; seismic testing also harmful.