7.1 Introduction to Air Pollution

• air pollution: anything in the atmosphere that is harmful to organisms

• primary pollutants: emitted directly into the atmosphere

  • can be natural or anthropogenic (produced by humans)

    • ex. pollen, plant VOCs, volcanic ash, fossil fuel combustion

• secondary pollutants: forms after entering the atmosphere

  • as a result of interactions with other atmospheric gases or sunlight rays

    • ex. ozone, acid rain

• sources of pollution can be natural, mobile, or stationary

• NAAQS of Clear Air Act: established standards to identify air pollutants

  • includes SO2, PM, Pb, O3, NO2, CO

  • health effects of lead: anemia, lower IQ, nerve damage, behavioral issues, hypertension, cardiovascular disease, reading/learning disabilities

• combustion of fossil fuels → CO2 production that had not reached the atmosphere in millions of years

• coal contains many impurities collected from trapped sediments

  • coal combustion → sulfur dioxide (SO2) production + toxic metals (lead, mercury, etc) + PM

  • limited through filters, scrubbers, clean coal processes, etc.

• air pollution comes from plant matter: carbon, hydrogen, nitrogen, oxygen, sulfur

  • voc - volatile organic compounds

  • PM - particulate matter (course & fine particles)

  • irritates human body (ie. eyes, nose, throat)

  • exacerbate lung conditions and damage

  • damage to plant tissue

7.2 Photochemical Smog

• VOCs = volatile organic compounds

  • can vaporize at room temp

  • increased presence in the atmosphere

    • ex. formaldehyde, gasoline, trees, plant oils

• formation includes VOCs + sunlight/heat = PANS/O3

  • NO + VOC + O2 + UV = O3 + PANs

  • ozone peaks during the afternoon after temperature and sun intensity increases

  • higher in sunny warmer climates

  • higher in the summer

  • irritates eyes, nose, throat

  • worsens heart/lung conditions

  • cause lung cancer from long-term exposure

• tropospheric ozone

  • can worsen bronchitis and emphysema

  • triggers asthma

  • permanent lung damage

  • reduced life for plants from lead damage

  • reduction of photochemical smog:

• catalytic converters: NO → O2 + N2

• CO + hydrocarbons → CO2 + H2O

  • reduce VOCs: pumping gas at night, following gas refueling instructions

  • improve fuel efficiency

  • reduce the use of internal combustion

  • reduce health impacts

7.3 Thermal Inversion

• normal conditions: altitude increases = temperature decreases

  • reversed in thermal inversion occurring in upper Earth layers

• thermal inversion: hotter air near the surface traps cooler air above

  • traps cooler denser air and pollutants (PM)

• more prone in particular geographic areas

  • valleys, mountain ranges, coastal winds

  • intensified by pollution (ie. industrialization, urbanization, major vehicle usage)

    • ex. los angles, mexico city

7.4 Atmospheric Pressure & CO2

• natural sources of CO2 emissions: respiration, diffusion, biomass decomposition, wildfires, volcanoes, etc.

  • considered fast carbon (not harmful to human health)

  • fossil carbon emissions → excess CO2 buildup → ecosystem disruption and health impacts

• particulate matter (PM): particles in the air that can be inhaled

  • inhalable → =< 10 microns (0.001 mm)

  • 2.5 < x < 10 → upper respiratory concern

  • <= 2.5 → lower respiratory concern

    • ex. pollen, spores, bacteria, dust, sea salt, dust mites, wildfire emissions, etc.

  • exacerbates lung conditions, pneumonia, stuffy nose, eye irritation, skin rash, etc.

7.5 Indoor Air Pollutants

• natural sources: mold, dust, radon

• human sources: asbestos, smoke

  • mold: found in places with poor ventilation

    • caused by water leakage + too much humidity

    • leads to eye, nose, and ear irritation and respiratory illness

  • dust: consists of particulates of different sizes

    • resolved by frequently changing home A/C filters

  • smoke: irritates and damages respiratory systems

    • comes from candles, fireplaces, gas stoves, heaters, cigarettes, wildfires

  • radon: decaying uranium in rocks & soil

    • seeps into buildings from cracks in basement walls & floors

    • can be carried in groundwater

    • can cause lung cancer through inhalation (2nd leading cause of cancer)

    • can be easily tested for and solved by sealing cracks and vents

  • asbestos: used for insulation

    • can cause lung cancer

    • has been banned from buildings and schools

• home building products can contribute to indoor air pollution

  • lead: found in older homes

  • VOCs: found in furniture, carpets, cleaning supplies, dryer sheets, etc.

  • formaldehyde: found in woods, carpets, glues, and resins

• combustion of carbon monoxide → CO poisoning

  • can be found in small engines, stoves, lanterns, fireplaces, cars, etc.

  • causes asphyxia = impairs RBC ability to carrying O2 in body → dizziness, nausea, suffocation

7.6 Reduction of Air Pollutants

• clean air act (CAA): regulates harmful emission of air pollutants

  • regulated at a national level with the help of state govs and tribes

  • create/enforce air quality standards

  • reducing vehicle emission: removing lead in gasoline, using cleaner technologies in transportation

  • reducing acid rain: setting pollution levels for industries, technologies to reduce sulfur/nitrogen oxide

  • pollutants that harm the ozone layer: removing greenhouse gases, regulating ground-level ozone

  • alternative fuels: increase the amount of renewable fuel that can be added to gasoline

    • ex. ethanol, propane, natural gas, biofuels, etc.

  • other solutions: energy efficiency, using water-based paints and cleaners, improved transportation planning, higher fuel standards, composting, recycling, carpooling, etc.

• vapor recovery nozzle: prevents fumes from escaping into the atmosphere when fueling a vehicle

  • captures the vapors → underground storage tank

  • ORVR (onboard refueling vapor recovering systems): added to cares to burn vapors in the car’s combustion chamber

• catalytic converters: reduces emission toxicity

  • converts CO NO2 and VOCs → O2, CO2, H2O, N2O

  • removes or adds oxygen based on gas being converted

  • hydrocarbons → CO2, H2O

• scrubbers: removes particulates or gases from industrial exhaust streams

  • removes gases such as sulfur and nitrogen oxides using a spray or mist to capture or change pollutants

  • sulfur oxide → limestone (buffer) + water → gypsum

  • dry: uses dry particles (reagents) → particles fall to the screen that collects them

  • not as effective as wet scrubbers

• electrostatic precipitators: adds a charge to pollutants → stick to chamber & allow clean air to leave the chamber

  • waste → sludge and ash that is taken to a landfill

  • leads to the contamination of large areas of land

7.7 Acid Rain

• pH → measures acidity + alkalinity in a substance

  • measured on a logarithmic scale

  • rainwater: 5.6

  • acid rain: 4.3

• NOx (vehicle emissions) + water → nitrous & nitric acid

  • natural sources of gases: volcanoes, geysers, hot springs

  • nitric + sulfuric acid → dry deposition + rain/snow

  • reacts with water (H2O) to create precipitation

• impacts communities that are downwind of coal-burning plants

• pollutants can travel long distances

• has many effects on natural ecosystems and human structures

  • aluminum toxicity: adds aluminum ions that are toxic to aquatic/plant life

  • calcium deficiencies: resulted from aluminum presence in soil → prevent calcium absorption → hinders regular cell processes →

  • reduced photosynthesis: nutrient deficiencies → changes in soil chemistry → photosynthesis less effective and productive

  • acidic lakes → death, deformities, and damaged eggs

  • erodes marble and limestone → destruction of human structures

• type of soil determines resistance to acid deposition

  • soils rich in magnesium, calcium carbonate, and limestone → neutralize acid → prevents acid from damaging soil

  • granite + poor nutrient soils → vulnerable to acid deposition (ie. high elevated areas)

7.8 Noise Pollution

• prolonged exposure to sound at high levels → physiological stress and hearing loss

  • comes from transportation, construction, and industrial activity in urban areas

  • measured in decibels (logarithmic scale)

  • dangerous to human hearing >= 86 dBAs

• transportation: railroads, mass transit, sirens, airports, heavy traffic, motocycles

• machinery from industry

• construction: trucks, jackhammers, nail guns

  • hearing loss: loud sounds → permanent damage to hair cells (curved and scattered)

  • can also cause stress, anxiety, depression, high blood pressure, heart disease

• primarily affects those in urban areas

• us noise control act (1972): allows EPA to regulate emissions from major noise pollution sources

• occupational safety and health association (osha): limits noise exposure in workplaces

• quiet communities act: provides funding for reducing noise in airports

• also affects animals negatively

  • induces stress → reduced reproduction, health decline, and disrupted communication

    • ex. dolphins rely on sound to communicate → interfered by vessels and machinery in the ocean

  • masks sounds between prey and predators

    • disrupts their symbiotic relationship

    • disturbs predators and exposes prey

  • alter migration routes: animals avoid areas of loud noise that were once filled with resource sto fulfill their survival needs