APES Air Pollution Study Notes

Air Pollution: Sources, Effects, and Reduction

Atmospheric CO_{2} and Particulates (Topic 7.4)

Enduring Understanding

STB-2: Human activities have physical, chemical, and biological consequences for the atmosphere.

Natural Sources of CO_{2}

Learning Objective STB-2.D: Describe natural sources of CO_{2} and particulates.
- Essential Knowledge STB-2.D.1: CO_{2} appears naturally in the atmosphere from sources such as:
  - Respiration: Cellular respiration, including decomposition, is a significant natural source.
    - Aerobic respiration: \text{C}{6}\text{H}{12}\text{O}{6} + 6\text{O}{2} \rightarrow 6\text{CO}{2} + 6\text{H}{2}\text{O}
    - Anaerobic pathways (other than methanogenesis): e.g., alcoholic fermentation.
  - Decomposition: The breakdown of organic matter by organisms.
  - Volcanic eruptions: Release CO_{2} and other gases into the atmosphere.
  - Combustion: Natural fires contribute CO{2} (\text{C}{x}\text{H}{y} + \text{O}{2} \rightarrow \text{CO}{2} + \text{H}{2}\text{O}).

Natural Sources of Particulate Matter

Essential Knowledge STB-2.D.2: There are a variety of natural sources of particulate matter, including:
- Dust (e.g., from wind erosion, deserts).
- Pollen and mold spores.
- Volcanic ash.
- Sea salt spray.
- Forest fires.

Indoor Air Pollutants (Topic 7.5)

Human Activities and Atmospheric Consequences

Enduring Understanding STB-2: Human activities have physical, chemical, and biological consequences for the atmosphere.

Identification of Indoor Air Pollutants

Learning Objective STB-2.E: Identify indoor air pollutants.
- Essential Knowledge STB-2.E.3: Indoor air pollutants can come from natural sources, human-made sources, and combustion.
- Essential Knowledge STB-2.E.4: Common natural source indoor air pollutants include radon, mold, and dust.
- Essential Knowledge STB-2.E.5: Common human-made indoor air pollutants include insulation, Volatile Organic Compounds (VOCs) from furniture, paneling and carpets; formaldehyde from building materials, furniture, upholstery, and carpeting; and lead from paints.
- Essential Knowledge STB-2.E.6: Common combustion air pollutants include carbon monoxide, nitrogen oxides, sulfur dioxide, particulates, and tobacco smoke.

Natural Sources of Indoor Air Pollutants

Radon-222 (Rn-222)
- Essential Knowledge STB-2.E.7: Radon-222 is a naturally occurring radioactive gas produced by the decay of uranium (U) found in some rocks and soils.
- It is an intermediate step in the decay of uranium or thorium to lead.
- At ambient temperatures, it is a gas (boiling point = -61.7 ^{\circ}C).
- It is a radioactive, colorless, tasteless, odorless noble gas.
- It is short-lived; the most stable isotope, Rn-222, has a half-life of only 3.8 days.
- However, it is common due to the long half-lives of its parent isotopes (Uranium and Thorium).
Mold and Mold Spores
- Can cause eye, nose, and throat irritation; allergic reactions; trigger asthma attacks; and bleeding of lungs and nose.
- Indicates the house is decomposing (mold is a fungus and decomposer).
Dust

Human-Made (Anthropogenic) Sources of Indoor Air Pollutants

Insulation: Includes asbestos, fiberglass, rockwool, and other particulates.
Volatile Organic Compounds (VOCs):
- Indoor air typically has 2 to 10 times higher concentrations of VOCs than outdoor air.
- Common sources: paints, lacquers, stains, varnishes, waxes, paint strippers, cleaning supplies, pesticides, adhesives (glues), markers, printers and copiers, carbonless copy paper, carpeting, upholstery, dry-cleaning agents, furniture, etc.
- Formaldehyde: One of the most problematic VOCs, released from furniture, building material, flooring, upholstery, and carpeting, leading to sick building syndrome.
- Many of these sources degas over long periods, even at undetectable odor levels.
Lead: From paints (especially in older homes).

Combustion Air Pollutants

Essential Knowledge STB-2.E.1: Carbon monoxide is an indoor air pollutant classified as an asphyxiant.
Essential Knowledge STB-2.E.2: Indoor air pollutants classified as particulates include asbestos, dust, and smoke.
Sources: fireplaces, wood-burning stoves (including pellet stoves), coal-burning stoves, cooking fires, candles, smoking.
Combustion produces:
- CO_{2}
- CO (Carbon Monoxide): An asphyxiant that interferes with oxygen delivery in the blood.
- Ash: Particulate matter.
- Smoke: Particulate matter.
- Tobacco Smoke: Particulate and carcinogen.
- NO{\text{X}} (Nitrogen Oxides) and SO{2} (Sulfur Dioxide).
Concentrations of these pollutants depend on usage rate, duration, and ventilation.
Particulates (PM): Classified by size; PM_{2.5} (2.5 micrometers or smaller) is most concerning due to its ability to penetrate deep into the lungs.

Effects of Indoor Air Pollutants

Learning Objective STB-2.F: Describe the effects of indoor air pollutants.

Effects of Radon Gas

Essential Knowledge STB-2.F.1: Radon gas can infiltrate homes as it moves up through the soil and enters homes via basements or cracks in walls or foundations. It can also dissolve in groundwater that enters homes through a well.
- Infiltration Pathways: Through sumps, cracks in foundations, fittings, fractured bedrock, or dissolved in well water.
Essential Knowledge STB-2.F.2: Exposure to radon gas can lead to radon-induced lung cancer.
- It is the second leading cause of lung cancer in America.
- It is the leading cause of lung cancer among nonsmokers.

Other Effects

Carbon Monoxide: Asphyxiation, reduced oxygen transport in blood.
Particulates (e.g., asbestos, dust, smoke): Respiratory issues, lung damage, cancer (e.g., from asbestos and tobacco smoke).
VOCs and Formaldehyde: Irritation of eyes, nose, throat; headaches, nausea, damage to liver, kidney, central nervous system; long-term exposure linked to cancer. Contributes to Sick Building Syndrome.
Mold: Respiratory problems, allergies, asthma attacks, other health issues.

Reduction of Air Pollutants (Topic 7.6)

Reducing Air Pollutants at the Source

Enduring Understanding STB-2: Human activities have physical, chemical, and biological consequences for the atmosphere.
Learning Objective STB-2.G: Explain how air pollutants can be reduced at the source.
- Essential Knowledge STB-2.G.1: Methods to reduce air pollutants include regulatory practices, conservation practices, and alternative fuels.

Technical Solutions and Devices for Air Pollution Control

Essential Knowledge STB-2.G.2: A vapor recovery nozzle is an air pollution control device on a gasoline pump that prevents fumes from escaping into the atmosphere when fueling a motor vehicle.
Essential Knowledge STB-2.G.3: A catalytic converter is an air pollution control device for internal combustion engines that converts pollutants (CO, NO{\text{X}}, and hydrocarbons) in exhaust into less harmful molecules (CO{2}, N{2}, O{2}, and H_{2}O).
- Installed in the exhaust system of internal combustion engine (ICE) vehicles.
Essential Knowledge STB-2.G.4: Wet and dry scrubbers are air pollution control devices that remove particulates and/or gases from industrial exhaust streams.
- Wet scrubbers: Use a liquid to remove pollutants (e.g., combining SO{2} with dissolved limestone to produce pH-neutral calcium sulfate, CaSO{4}).
- Dry scrubbers: Use a dry medium (dust or slurry) for pollutants to bind to.
Essential Knowledge STB-2.G.5: Methods to reduce air pollution from coal-burning power plants include scrubbers and electrostatic precipitators.
- Electrostatic Precipitator (ESP): An air pollution control device that passes industrial exhaust across charged electrodes, which attracts (and then collects) particulates.
- Bag Filter (Baghouse Filter): A fabric device that removes particulates from industrial exhaust.

Other Reduction Methods

Legislature (Regulation & Taxes): Emissions taxes, international agreements.
Energy Conservation: Reducing energy consumption reduces emissions from power generation and transportation.
Alternative Fuels: Using cleaner energy sources instead of fossil fuels.
Individual Action: Reducing personal consumption of polluting products, promoting awareness.

The Clean Air Act (CAA)

Drafted: 1963
Amended: 1965, 1970, 1977, and 1990
Purpose: Defines EPA's responsibilities for improving U.S. air quality and stratospheric ozone.
EPA created: 1970.
1963 Function: To protect and improve air quality for the welfare of the U.S. populace; promote research in air pollution control; promote and execute state and local air pollution control programs.
1965 (National Emissions Standards Act): Evolved federal framework for automobile pollution regulation, setting federal standards for automobile manufacturers.
1970: Authorized comprehensive federal and state regulations to limit emissions from both stationary (industrial) and mobile (transportation) sources.
- Implemented a cap and trade program for SO_{2} from coal-burning facilities.
- Put the Clean Air Act under the jurisdiction of the EPA.
1977: Further improved air quality standard goals and programs.
1990: Substantially increased federal authority and responsibility for air quality in the U.S.; broadened to include controls for acid rain and permits for stationary sources of pollution.
Effects of CAA: Significantly improved air quality in the U.S., served as a model for legislation in other countries, protected health and environment in the U.S.

Acid Rain (Acid Deposition) (Topic 7.7)

Description of Acid Deposition

Enduring Understanding STB-2: Human activities have physical, chemical, and biological consequences for the atmosphere.
Learning Objective STB-2.H: Describe acid deposition.
- Essential Knowledge STB-2.H.1: Acid rain and deposition result from nitrogen oxides (NO{\text{X}}) and sulfur oxides (SO{\text{2}}) from anthropogenic and natural sources in the atmosphere.
- Essential Knowledge STB-2.H.2: Nitric oxides that cause acid deposition come from motor vehicles and coal-burning power plants. Sulfur dioxides that cause acid deposition come from coal-burning power plants.
Forms of Acid Deposition:
- Wet Deposition: Acid precipitation (rain, snow, fog).
- Dry Deposition: Settling of acidic gases and dust particles.
Acidity: Unusually acidic (low pH, high concentration of H^{+} ions) compared to normal rainwater (which is slightly acidic due to carbonic acid).
Precursors: Primarily results from NO{\text{X}}, SO{2}, and VOC emissions.
Sources: Primarily coal-burning power plants, factories, vehicle emissions.
Geographic Impact: Primarily affects areas downwind of industrial regions, such as the Eastern third of North America, Europe, industrial Russia, and East Asia.
Chemical Reaction Example: \text{SO}{2} + \text{O}{2} + \text{H}{2}\text{O} \rightarrow \text{H}{2}\text{SO}_{4} (sulfuric acid form).

Effects of Acid Deposition on the Environment

Learning Objective STB-2.I: Describe the effects of acid deposition on the environment.
- Essential Knowledge STB-2.I.1: Acid deposition mainly affects communities downwind from coal-burning power plants.
- Essential Knowledge STB-2.I.2: Acid rain and deposition can lead to the acidification of soils and bodies of water and the corrosion of human-made structures.
Effects on Water Chemistry:
- Lowers pH of lakes and streams.
- Can kill adult fish, prevent fish eggs from hatching, dissolve shells or prevent shell formation of mollusks and other organisms, and kill insect larvae due to exceeding ecological tolerances.
- Acids leach aluminum from soil, carrying it to bodies of water, where aluminum is toxic to most organisms in moderate/high concentrations.
- Can affect ocean pH, but typically less than atmospheric CO_{2} due to the ocean's size. Effects are more pronounced in shallow, offshore areas with few currents or in estuaries fed by acidic rivers.
Effects on Soil Chemistry:
- Lowers soil pH.
- Can kill soil microbes (mostly by denaturing enzymes).
- Leaches essential nutrients from soil.
- Reduces plant growth (reduced photosynthesis and mineral uptake), potentially killing plants.
- Leaches heavy metals from soil, making them soluble and transportable.
Regional Differences: Impact depends on local conditions, especially soil and lake/riverbed composition.
- Limestone bedrock can buffer the pH, reducing negative effects due to its basic nature and easy dissolution.

Effects of Acid Rain on Humans

Little to no direct health effects from contact with dilute acid rain.
However, the precursor pollutants (NO{\text{X}}, SO{2}, VOCs) that create acid rain do affect human health.
Corrosion of Structures: Acid rain dissolves buildings, particularly those made of limestone and marble, leading to weathering of buildings and statues.

Reduction of Acid Rain

Requires a reduction in NO{\text{X}}, SO{2}, and VOC emissions.
Technical Solutions:
- Catalytic converters on vehicles: Reduce NO_{\text{X}} and VOCs.
- Flue-gas desulfurization (SO_{2} scrubbers) in coal-burning power plants.
  - Wet scrubbers combine SO{2} with dissolved limestone, producing pH-neutral calcium sulfate (CaSO{4}), which can be sold to industry or disposed of.
Legislation: National and international emissions controls and taxes.

Noise Pollution (Topic 7.8)

Human Activities Causing Noise Pollution and its Effects

Enduring Understanding STB-2: Human activities have physical, chemical, and biological consequences for the atmosphere.
Learning Objective STB-2.J: Describe human activities that result in noise pollution and its effects.
- Essential Knowledge STB-2.J.1: Noise pollution is sound at levels high enough to cause physiological stress and hearing loss.
- Essential Knowledge STB-2.J.2: Sources of noise pollution in urban areas include transportation, construction, and domestic and industrial activity.
- Sources: Ranges from transportation (cars, planes, trains) to heavy machinery, construction, industrial activity, music, and explosions.

Effects on Humans

Elevated stress.
Cardiovascular disorders, including hypertension.
Hearing loss (including tinnitus).
Sleep disruption.

Effects on Wildlife

Essential Knowledge STB-2.J.3: Some effects of noise pollution on animals in ecological systems include stress, the masking of sounds used to communicate or hunt, damaged hearing, and causing changes to migratory routes.
Similar Effects to Humans: Elevated stress, altered sleep schedules.
Marine Species:
- Many marine mammals, fish, and arthropods use sound as their primary means of navigation, communication, mating courtships, predator avoidance, and hunting.
- Anthropogenic sounds (sonar, transportation, explosions, offshore drilling, seismic exploration for oil and gas) disrupt marine species.
- Noise pollution is implicated in high levels of whale beaching themselves.
Terrestrial Species:
- Many terrestrial species use sound for communication, hunting, predator avoidance, echolocation, and migration.
- Masking: Inability to hear important ecological cues like predators and mates.
- Physiological effects: Hearing loss, stress, hypertension, elevated heart rate.
- Behavioral effects: Lowered reproduction rates, abandonment of mates, abandonment of territory (migrating away), temporal variation in sound (e.g., birds singing at dusk instead of during loud daytime hours).
- Ecological effects: Trophic cascades within ecosystems due to the above effects.
- Invertebrates may be hypersensitive due to antennae and hairs picking up air vibrations.