SS

Unit 7 - Atomspheric Pressure

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