Unit 8: Pollution: module 4.42: Air pollution

Module 4.42 (module 42, 4th edition text)

Big ideas: air is shared by everyone on the planet, crosses international borders without consent, impacts innocents with little power.

Contrast this with solid, toxic or radioactive waste: usually disposed of on your own land, or with rivers, which demonstrate "continuity downstream"

What is a "criteria"? good/bad

6 major pollutants: “criteria pollutants”

• Sulfur dioxide: SO2 (could also be SOx)
• Nitrogen oxides: NOx (could be NO, NO2, or NO3)
• Carbon monoxide: CO
• Particulate matter: PM (PM 2.5, PM 5, PM10)
• Ozone: O3
• Lead: Pb

Mnemonic: SOX/NOX, CO/O3, PM/Pb

Added in 2007: CO2, VOC, Hg

From your text:

Context and relevance:

SOx: Sulfur Dioxide (SO2) and other SOx versions

• From Methionine (amino acid in living things) in fossil fuels (look up the structure of this)
  
• Combines with water in the air to make H2SO4 (sulfuric acid, acid rain)
  
• When you breathe it, it burns your lungs, stings your eyes
• May look like "yellow smog"
• One example is VOG: sulfur dioxide and ash (volcanic glass)

NOx: Nitric oxide (NO2) and other NOx versions

• Various forms of oxidized nitrogen, which alone is inert and makes up 78% of the atmosphere at sea level
  
• From high temperature combustion (e.g. auto engines, esp. high efficiency ones, which burn at higher temps)
  
• Also from decomposition of fertilizers (e.g. Ammonium Nitrate)
  
• Combines with water to make HNO3 (nitric acid) which also burns your lungs and eyes

CO: Carbon monoxide

• Emission from car exhaust, or other incomplete combustion:  C + O2 —> CO2
• Many people die camping by burning stoves in their tent without enough oxygen, forming carbon monoxide
• If not enough O2, then CO forms, like in a closed space (tent, hut, cold house in Texas)
  
• Toxic, permanently attaches to your hemoglobin rendering it useless for respiration. (30 day life cycle for your hemoglobin)
  
• Imagine the town van, but nobody gets off. The bus still goes, but nobody goes to town.
• For 30 days (until your red blood cells are replaced) no seats on the bus, no oxygen.

Ozone

• Ozone is formed by sunlight, splitting O2 into O which then joins another O2 to make O3
• Ozone in stratosphere is good, in troposphere bad
  
• Ozone (O3) blocks UV radiation, while Oxygen (O2) does not
  
• Stratospheric ozone is necessary to filter UV radiation. CFC (chloro-fluro-carbons) destroy this layer
• This caused an ozone hole over Antarctica: Why there?
• 
  

• How did we solve this? The 1987 Montreal Protocol:
  
• Tropospheric ozone causes lung and eye irritation, and is toxic to some organisms
• You may have heard of ozone generators used in hotel rooms to absorb smoke

PM: Particulate Matter

• Look up alveolus in your lungs
• Particulate Matter (PM) is basically soot (carbon)
• PM2.5 is 2.5 microns in size, PM10 is 10 microns in size (there is also PM5)
  
• PM2.5 is most dangerous, smaller particles lodge deep in the lungs, beyond ability of pulmonary cilia to flush out
  
• PM5, PM10 larger particles, get caught by cilia
  
• Main cause: coal fired power plants, diesel engines, oil fired power plants (carbon soot)
  
• See also vog: PM2.5 particles of ash (glass shards) with SO2 dissolved in water droplets (sulfuric acid): physical abrasive + corrosive acid = respiratory damage
• Fun fact: smokers get colds more often because tar in tobacco gums up the cilia, so they can't brush away germs and viruses.

Pb: Lead

• In the old days, there was leaded gasoline, and highly leaded gasoline (called "super" or "ethyl" because they used tetraethyl lead as an additive to improve power)
• Gasoline additive (tetraethyl lead improves octane rating cheaply), replaced by other worse carcinogenic (cancer causing) chemicals like MTBE: https://en.wikipedia.org/wiki/Methyl_tert-butyl_ether
• Decreases mental capacity (e.g. Roman insanity theory)
  
• Coal smoke contains lead, along with Mercury and other heavy metals. Sludge from mining is worse.
  

VOC: Volatile Organic Compounds

• Volatile organic compounds, e.g. gasoline vapors (why your gas cap must be on or you get a dashboard warning): https://en.wikipedia.org/wiki/Volatile_organic_compound
• Aerosol vaporizers are also VOC generators (indoor air pollution)
• Remember water striders sitting on water, due to surface tension?
• Your alveoli are surrounded by water (blood) so they need a surfactant (detergent) to break the surface tension so they can expand you can breathe.
• If you breathe in VOC's (siphoning gasoline, vaping, or in the case of premature babies), the surfactant is gone, and you cannot breathe.
• Vaping is a concentrated version of VOCs, dissolving the surfactant in your lungs, causing "chemical pneumonia", only seen before in anesthesia and people siphoning gasoline or premature babies.

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