chapter 15: air pollution
chapter 15: air pollution
Big ideas: air is shared by everyone on the planet, crosses international borders without consent, impacts innocents with little power.
6 major pollutants: “criteria pollutants”
- Sulfur dioxide: SO2
- Nitrogen oxides:NOx
- Carbon monoxide: CO
- Particulate matter: PM (PM 2.5, PM 5, PM10)
- Ozone: O3
- Lead: Pb
Mnemonic: SOX/NOX, CO/O3, PM/Pb
2007 added CO2, VOC, Hg
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SOx: Sulfur Dioxide (SO2) and other SOx versions
From Methionine (amino acid in living things) in fossil fuels
Combines with water in the air to make H2SO4 (sulfuric acid)
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)
CO: Carbon monoxide
Emission from car exhaust, or other incomplete combustion:
C + O2 —> CO2
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 hemoglobin
See also CO2 and climate change, > 400ppm since 2012, 420+ppm today (look this up)
Air Quality monitoring: Purple Air:
Check out other locations...
PM: Particulate Matter
PM2.5 is 2.5 microns in size, PM10 is 10 microns in size
PM2.5 is most dangerous, smaller particles lodge deep in the lungs, beyond ability of pulmonary cilia to flush out
PM5, PM10 larger particles
Main cause: coal fired power plants, diesel engines, oil fired power plants (soot)
See also vog: PM2.5 particles of ash with SO2 dissolved in water droplets: physical abrasive + corrosive acid = respiratory damage
Ozone
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 way:
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This caused an ozone hole over antarctica:
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How did we solve this? The 1987 Montreal Protocol:
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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
Pb: Lead
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)
Found in coal smoke, 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
Smog and other photochemical reactions:
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Primary and secondary pollutants:
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Secondary pollutants: need a chemical reaction (often energy from sunlight) to form (see figures above)
Example: PhotoChemical Smog: Photo (light) Chemical (reaction) smog
See PANs: Peroxyacyl nitrates: formed from VOCs, NOx
https://en.wikipedia.org/wiki/Peroxyacyl_nitrates
Thermal inversions: London fog, US, Donora, PA 1948 k.20, sick 7000
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1952 London 4000-12,000 dead, three nights
Mexico city 1996 300 dead, 400K sick
How?
Normally, the sun heats the surface, warming the air there, which rises. Cooler air aloft then falls to replace this rising air.
In an inversion, warmer air aloft traps the air at the surface (no temperature difference, so no mixing), causing the pollution to be trapped in the lower levels. Most dangerous in valleys or bowl shaped cities (London, Mexico City, Denver, Donora).
Los Angeles has severe smog in the daytime, when hotter air draws in ocean air ("onshore breeze"), but the cycle reverses at night when the water is warmer than the land, so they have an "offshore breeze". Surfers like the first one.
Acid rain: plants, fish, structures. Check this out:
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SO2 + O2, water = H2SO4 (sulfuric acid)
NO3 + O2, water = HNO3 (nitric acid)
“Acid snow” yes, acid snow...
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W. VA had rain more acidic than stomach acid in the 1970's
Important: Know how a power plant air scrubber works (just like the nuclear plant diagram)
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IAP-indoor air pollution
Leading cause of death in LDC (women). LDC is the latest term for "Lesser Developed Countries"
Burning manure for fuel, open pit fires, CO, PM10
Sick building syndrome: formaldehyde, CO2, VOC
Check out the Living Building Challenge and LEED Platinum in the elab hallway
Main culprits:
- VOC (paints, aerosols, vaporizers)
- CO (burning)
- Radon (radioactive rocks)
- Lead (paint, gasoline)
- Formaldehyde (adhesives, wood products, carpet glue)
- Asbestos (insulation, tiles, flooring)
- PM10 (soot from burning)
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Asbestos-asbestosis, mesothelioma (like the ads on TV, usually aimed at Military folks or shipyard workers)
Radon 222-lung cancer (smoke demo-lungs)-#2 cause of lung cancer in the US (behind smoking of course)
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AIR QUALITY LABS-From the AP exam folks
• Air Quality: Air quality can be assessed using various
methods.
• Particulates: Sticky paper can be used to collect
air particulates from various sources, and then the
paper can be examined under a microscope. It is
not possible to see the smallest particulates, but
they do color the white paper.
• Ozone: In this lab, an ecobadge or a homemade
potassium iodide gel sampler is hung or worn in
order to collect data on tropospheric ozone. The
badge or KI sample changes color in the presence
of ozone and becomes more intensely colored as
the amount of ozone increases.
• Carbon dioxide: In this lab, a commercial sampling
device is used to determine the amount of
carbon dioxide in an air sample. Car exhaust,
burning tobacco, or other pollutants can also be
sampled.
Pollution roundup:
Chapter 8 of Princeton Review for AP:
http://physics.hpa.edu/physics/apenvsci/apes_exam_prep/apes_princeton/ch08-pollution.pdf