APES UNIT 7

🌍 Air Pollution

Occurs when harmful substances enter Earth's atmosphere.

📏 Parts per Million (ppm)

• Most common unit for measuring air pollutants.

⚠ Primary Pollutants

Emitted directly into the air.

🔄 Secondary Pollutants

Formed when primary pollutants react in the atmosphere.

🏭 Point Source Pollution

Comes from a single, identifiable source (e.g., a factory smokestack).

🌎 Non-Point Source Pollution

Comes from widespread, multiple sources (e.g., car emissions).

🧪 Criteria Air Pollutants

• A set of 8 pollutants causing smog, acid rain, & health hazards.

• Emitted from industry, mining, transportation, power, & agriculture.

🌫 Industrial Smog (Gray Smog)

Sulfur-based smog from burning coal/oil.

🛠 Formation of Industrial Smog

• Coal/oil combustion → CO₂, CO, & soot (PM).

• Sulfur compounds react to form sulfuric acid & ammonium sulfate

🚨 Carbon Monoxide (CO)

• Colorless, odorless, tasteless gas from incomplete combustion.

• Sources: Fires, fossil fuel burning, volcanic activity.

• Solutions: Public transport, catalytic converters, renewable energy.

🔩 Lead (Pb)

• Found in batteries, bullets, radiation shields.

• Exposure: Inhalation, contaminated food/water.

• Effects: Anemia, cognitive impairment, miscarriage, death.

💨 Nitrogen Oxides (NOx)

• Includes nitric oxide (NO) & nitrogen dioxide (NO₂).

• Produced in high-temp combustion (cars, industry).

• Nitrous oxide (N₂O): Causes ozone depletion.

☁ Ozone (O₃) – Tropospheric (Ground-Level)

• Secondary pollutant harmful to localized areas.

• Effects: Lung irritation, asthma, heart disease, immune suppression.

🧪 Peroxyacyl Nitrates (PANs)

• Secondary pollutants that travel far from source.

• Effects: Eye irritation, respiratory issues, crop damage.

• Reduction methods: Reduce fossil fuels, limit wood-burning, improve smokestack filters.

🌋 Sulfur Dioxide (SO₂)

• From power plants, refineries, fossil fuel burning.

• Effects: Acid rain, respiratory issues, crop damage, stonework erosion.

• Reduction methods: Use scrubbers, wash coal, fluidized gas combustion.

🌎 Suspended Particulate Matter (PMx)

• Microscopic solid or liquid particles in the air.

• Effects: Acidification of lakes, ecosystem damage, soil depletion, respiratory problems.

• Reduction: Improve emissions standards, reduce energy use, limit burning.

🌪 Sources of PMx Pollution

🔹 Natural: Dust storms, wildfires, sea spray, volcanoes.
🔸 Human-caused: Fossil fuel burning, waste incineration, deforestation.

🧪 Volatile Organic Compounds (VOCs)

• Organic chemicals with high vapor pressure (evaporate easily).

• Health effects: Cancer, nerve damage, headaches, nausea, eye/throat irritation.

☁ Photochemical Smog (Brown Smog)

• Catalyzed by UV radiation

• Nitrogen-based pollution

• Appears brown due to nitrogen oxides

🌅 Formation Timeline of Photochemical Smog

6 A.M.–9 A.M. 🚗

• Morning traffic increases nitrogen oxides (NOx) & VOCs.

9 A.M.–11 A.M. 🔄

• NO & VOCs react → forming nitrogen dioxide (NO₂).

11 A.M.–4 P.M. ☀

• Intense sunlight breaks down NO₂ → Ozone (O₃) increases.

• NO₂ reacts with water vapor → Nitric acid (HNO₃) & Nitric oxide (NO).

• NO₂ reacts with VOCs → forming Toxic PANs.

4 P.M.–Sunset 🌇

• Sunlight decreases → ozone production stops.

🌍 Effects of Photochemical Smog

• Irritates eyes & lungs

• Reduces visibility

• Damages crops & vegetation

🚦 Ways to Reduce Photochemical Smog

• Reduce vehicle emissions

• Use alternative fuels

• Implement stricter industrial regulations

🌡 Thermal Inversion

• Occurs when air temperature increases with height instead of decreasing.

• Traps pollutants like smog close to the ground, worsening air quality.

🌙 When Does It Happen?

• At night, when the surface cools, cooling the air above it.

• When a warm air mass moves over colder air, trapping pollutants

🌍 Effects of Thermal Inversion

• Increases air pollution concentrations

• Harms human health (respiratory issues, irritation, asthma attacks)

• Reduces visibility

❄ Example:

• Antarctica has a nearly constant temperature inversion.

  🚦 Ways to Reduce Harmful Effects

  • Limit emissions during inversion events

  • Improve urban ventilation

  • Reduce vehicle & industrial pollution

🏢 “Sick Building” Syndrome (SBS)

A combination of health issues linked to poor indoor air quality in workplaces or homes.

🧱 Asbestos

• Properties: Inexpensive, durable, flexible, fireproof, and insulating.

• Health Risk: Can cause lung diseases, including mesothelioma.

🚗 Carbon Monoxide (CO) Poisoning

• Most common fatal indoor air poisoning.

• Danger: CO binds to hemoglobin, blocking oxygen transport in the blood.

⚠ Formaldehyde

• A carcinogenic organic chemical found indoors.

• Linked to: Lung cancer.

🛑 Radon

• Invisible radioactive gas from radium decay.

• Health Risk: Can cause lung cancer.

🚬 Cigarette Smoke

• Contains 5,000+ chemicals, including 60 carcinogens like dioxin.

• Major cause of indoor air pollution.

🛠 Remediation Steps to Reduce Indoor Air Pollutants

✅ Add plants that absorb toxins
✅ No smoking indoors
✅ Install air purification systems
✅ Maintain filters and vents
✅ Monitor humidity to prevent mold
✅ Test for radon gas
✅ Use "green" cleaning products
✅ Apply natural pest control techniques

🚗 Catalytic Converter

Function: Converts toxic chemicals in vehicle exhaust into less harmful substances.

⚡ Catalyst

Role: Stimulates chemical reactions that convert combustion by-products into less toxic substances.

🔄 Three-Way Catalytic Converter

1⃣ Oxidation of CO → CO₂
2⃣ Oxidation of unburned hydrocarbons → CO₂ & H₂O
3⃣ Reduction of NOₓ → N₂ & O₂

💡 Fact: Catalytic converters remove hydrocarbons & harmful emissions but do not reduce CO₂ from fossil fuels.

🌍 Remediation Steps to Reduce Air Pollution

🚫 Ban open waste burning
🚗 Use smaller, fuel-efficient cars
🛣 Decrease unnecessary travel
☀ Distribute solar cook stoves
⚙ Maintain vehicles (regular tune-ups & oil changes)
🛑 Reduce idling & turn off engines while waiting
🚆 Use mass transit & carpool when possible
⚖ Toughen Corporate Average Fuel Economy (CAFE) standards
🛢 Reduce sulfur content in fuels through legislation
💨 Use fans instead of air conditioners
💡 Switch to LED or fluorescent lighting
🔍 Consider fuel efficiency when buying a car

🌧 Acid Deposition

Definition: Transformation of sulfur & nitrogen compounds into acidic wet or dry deposits on Earth.

🌀 Dry Deposition

• Acidic chemicals in the air stick to surfaces (buildings, trees, cars).

• Rainstorms wash them away, increasing acidic runoff.

💦 Wet Deposition

• Includes acid rain, fog, & snow.

• Affects plants, animals, and soil by increasing acidity.

🌲 Effects of Acid Rain

• Acidifies lakes & streams.

• Damages high-elevation forests & soils.

• Harms decomposers & mycorrhizal fungi.

⚠ Acid Shock

• Cause: Rapid melting of acidic snowpacks.

• Effect: Raises acid concentration in lakes & streams 5-10x higher than acidic rainfall.

🔬 Acid Deposition from Sulfur Dioxide (SO₂)

• Sources: Burning coal & oil, smelting metals, ocean spray, organic decay.

• Process:

  • SO₂ + H₂O → Sulfurous Acid (H₂SO₃)

  • H₂SO₃ + O₂ → Sulfuric Acid (H₂SO₄)

🔬 Acid Deposition from Nitrogen Oxides (NOₓ)

• Sources: Burning fossil fuels, volcanic gases, forest fires, lightning, soil bacteria.

⚠ Effects of Acid Deposition

• 🌊 Acid shock & fish kills.

• 🐾 Changes in animal life due to vegetation shifts.

• 🌱 Soil nutrient loss & reduced buffering capacity.

• ☠ Increased solubility of toxic metals (methyl mercury, lead, cadmium).

• 🔄 Ecosystem & food web disruptions.

🏙 Urban Heat Islands

• Definition: Metropolitan areas warmer than surroundings.

• 🌧 Effect: Increased rainfall (up to 30% more downwind of cities).

🔥 Causes of Higher Urban Temperatures

• 🚗 Transportation, AC, & lighting generate heat.

• 🏢 Buildings block thermal radiation.

• 🌳 Lack of vegetation & water reduces cooling.

• 🚧 Black asphalt absorbs heat instead of reflecting sunlight.

🏙 Street Canyon Effect

Definition: Narrow streets flanked by tall buildings trap heat & pollution.

🌡 Localized Greenhouse Effect

Urban pollution traps heat, worsening warming effects.

⚕ Impact on Residents

Health risks for people who cannot afford AC.

🔊 Noise Pollution

• Definition: Unwanted human-created sound that disrupts the environment.

• Main Source: Transportation (cars, planes, trains).

⚠ Effects of Noise Pollution

🦻 Hearing Loss

• Sensory hearing loss from inner ear damage is most common.

🧠 Cognitive & Emotional Effects

• Reduced alertness & memory.

• Increased anxiety & nervousness.

💓 Physical Health Effects

• Cardiovascular issues (high blood pressure, rapid heartbeat).

• Gastrointestinal problems (stomach issues).

🚗 Techniques to Reduce Roadway Noise

• 🛣 Traffic flow devices to reduce braking & acceleration.

• 🛑 Noise barriers along highways.

• 🏎 Improved tire designs & new road surfaces.

• ⏳ Restricted heavy-duty vehicle hours.

• 🚦 Lower speed limits.

✈ Techniques to Reduce Aircraft Noise

• 🛩 Develop quieter jet engines.

• 📅 Reschedule takeoff & landing times.

🏭 Techniques to Reduce Industrial Noise

• ⚙ New noise-reducing industrial technology.

• 🏢 Noise barriers in workplaces.

• 🚫 Local laws to control residential noise (power tools, loud music).