Rucete ✏ AP Environmental Science In a Nutshell
7. Atmospheric Pollution
This unit covers the causes and effects of air pollution, including smog, acid rain, indoor air pollutants, and greenhouse gases. It explains primary and secondary pollutants, the difference between point and non-point sources, and methods to reduce air and noise pollution. The unit also explores laws like the Clean Air Act and technologies like catalytic converters and scrubbers.
7.1 Introduction to Air Pollution
Air Pollution Basics
• Results from harmful substances entering the atmosphere.
• Responsible for millions of global deaths yearly (6+ million by 2050 projected).
Measurement
• Measured in parts per million (ppm) or parts per billion (ppb).
Primary Pollutants
• Emitted directly (e.g., CO, NOx, SO2, particulate matter).
Secondary Pollutants
• Formed by reactions in the atmosphere (e.g., ozone, PANs, acid rain).
Point Source vs. Non-Point Source
• Point source: single, identifiable source (e.g., smokestack).
• Non-point source: diffuse sources (e.g., car emissions).
Criteria Air Pollutants (EPA)
• CO, NOx, SOx, ozone, lead, particulate matter, VOCs, PANs.
• Cause smog, acid rain, respiratory problems, and environmental damage.
7.2 Photochemical Smog
Formation Steps
• VOCs + NOx + sunlight → O3 (ozone) + PANs
• Morning traffic increases NOx and VOCs → react by midday → peak ozone by afternoon.
Pollutants Involved
• Nitrogen oxides (NO, NO2)
• Volatile organic compounds (VOCs)
• Peroxyacyl nitrates (PANs)
• Ground-level ozone (O3)
7.3 Thermal Inversion
Definition
• Temperature increases with altitude, trapping cool air (and pollutants) near the surface.
Effects
• Traps smog and particulates near the ground.
• Leads to respiratory problems (e.g., asthma, bronchitis).
Common Conditions
• Occur at night or in valleys with stagnant air.
7.4 Atmospheric CO₂ and Particulates
Sources of CO₂
• Combustion of fossil fuels (transportation, power plants)
• Deforestation and land use change
• Industrial processes (cement, steel, agriculture)
Carbon Sequestration
• Long-term storage of CO₂ in forests, oceans, and soil.
• Techniques include reforestation, soil management, and direct air capture.
Particulate Matter (PM)
• Solid or liquid particles suspended in air (PM₁₀, PM₂.₅).
• Sources: construction, fires, agriculture, vehicles, coal combustion.
• Health impacts: respiratory and cardiovascular diseases, cancer.
7.5 Indoor Air Pollutants
Common Pollutants
• Carbon monoxide (CO) from combustion appliances.
• Particulates from tobacco, cooking, dust.
• VOCs from cleaning products, paints, furniture.
• Formaldehyde from building materials and insulation.
• Asbestos from old insulation (causes lung cancer and mesothelioma).
• Radon: radioactive gas from soil → causes lung cancer.
• Mold and pollen: biological pollutants triggering allergies and asthma.
Solutions
• Ventilation, air filtration, removing pollutant sources, sealing foundation cracks (radon mitigation).
7.6 Reduction of Air Pollutants
Clean Air Act (1970)
• Authorized EPA to set National Ambient Air Quality Standards (NAAQS) for major pollutants.
• Requires monitoring and reduction of emissions from power plants, industry, and vehicles.
Technologies
• Catalytic converters: reduce NOx, CO, and hydrocarbons in car exhaust.
• Scrubbers: remove SO₂ from coal power plant emissions.
• Electrostatic precipitators: remove particulates from smokestacks.
• Vapor recovery nozzles: prevent gas fumes from escaping at pumps.
7.7 Acid Rain
Causes
• Emission of sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) from burning fossil fuels.
• These gases react with water vapor to form sulfuric (H₂SO₄) and nitric (HNO₃) acids.
• Rain, snow, fog, or dry particles then carry acids to the ground.
Impacts
• Lowers pH of soil and water → harms plant growth and aquatic life.
• Leaches aluminum and heavy metals from soils into waterways.
• Damages buildings, statues, and infrastructure (especially limestone and marble).
• Reduces forest productivity and biodiversity.
Solutions
• Reduce SO₂ and NOₓ emissions (scrubbers, cleaner fuels).
• Switch to renewable energy and increase energy efficiency.
• Lime application to neutralize acidic soils or lakes.
7.8 Noise Pollution
Sources
• Transportation (cars, trains, planes), construction, industry, urbanization.
• Also includes sonar from ships and submarines affecting marine life.
Impacts
• Causes hearing loss, stress, and sleep disruption in humans.
• Disrupts wildlife communication, navigation, reproduction, and migration.
• Marine mammals are especially vulnerable to sonar and seismic exploration.
Solutions
• Noise barriers, quieter equipment, urban planning, and regulations.
• Marine solutions: rerouting ships, sonar restrictions, quieting ship engines.
In a Nutshell
Atmospheric pollution includes harmful gases and particles that originate from both natural and human sources. These pollutants lead to smog, acid rain, health issues, and environmental damage. Laws like the Clean Air Act and technologies like scrubbers and catalytic converters have reduced emissions. Indoor pollutants, noise pollution, and thermal inversions also pose major concerns. Understanding pollutant sources and effects is crucial for creating cleaner, healthier environments for humans and ecosystems.