Cutting the topic
First question is huge, requiring more research. Any answers are provisional. Scientifically, any risk estimate should be set high; political and economic pressures push toward low estimate.
The 2nd question echoes "tragedy of commons."
Thermodynamics teaches that any energy produced has accompanying heat, typically twice the energy.
Heat Islands. Cities are heat islands -- typically
degrees warmer than rural area. Two reasons:
(i) large consumption of energy and
(ii) large surfaces absorb energy that reradiates or
requires more cooling (energy!).
How bad is this?
Definitions: dose = potency × exposure
health risk = dose × exposed populations
Pollutant size matters
The nose can reject large particles and the lung can tolerate, if with irritation, smaller ones.
Dangerous sizes. Particles smaller than 2.5 µm are trapped in lungs. Soluble ones pass into blood. (PM2.5)
Health risk is hard to set. Concentration levels are low and potency is hard to measure. Different countries, states and cities set different levels. 2005 State of the Air, American Lung Assoc.
Many pollutants. In additions to the oxides of C, N & S, chemical processes supply dangerous elements: Pb, Cd, Ni, Be, Hg, As, V & Cr. Don't forget asbestos and polycyclic organic matter.
Where is safe? Rural areas are less polluted; less populated countries are better. But much pollution crosses boundaries.
Few can doubt pollutants are hazardous to human health and to the whole ecoculture. The Clean Air Acts (1970, 1977, 1990) set standards administered by EPA.
For the "worst" five, sources are diverse:
|NO2||fuel combustion, industrial processes, transportation|
|mercury (Hg)||all combustion (fuel, stationary)|
|volatile organic compounds (VOC)||stationary combustion, transportation|
Worst states are OH, TX, PA, IN, KY
Largest sources of NO2 in troposphere (within 5-9 miles of earth) are burning biomass, automobiles and ships at sea!
Long distance travelers.
Saharan sand in Miami.
Ancient Asian dust in Greenland ice.
American pollution reaches Britain; by jet stream?
Asian haze over entire Northern Hemisphere.
The Phase I targets of CAAA largely met. NO2 is a disappointment &rarr even smaller decrease in ozone
|Est. Compliance Costs||$7 B||$26 B||$27 B|
|Act. Compliance Costs||$2 B||$8 B||$9 B|
|Estimated Benefits||$110 B|
|( includes better health, visibility, better crops)|
Most cost uncertainties were associated with reducing SO2. In the 1980s when CAAA was under active discussion there were fears that
Mere $0.8 B/yr produced reduction greater than requested. Most utilities switched to low-sulfur coal, altho many went for expensive scrubbers. Also coal transport cost dropped. But the real surprise was ...
Novel feature of 1990 CAAA was allowances: the right to emit ton of SO2 good in any year. At any year's end, company must "pay" as many allowances as its total emissions that year. The utilities could freely buy, sell, or bank allowances
Initially allowances granted yearly on historical basis. Renewable sources could earn allowances on basis of electricity generated, pollution avoided or set-asides (fraction of allowances).
Use.The 1992 price of $250/allowance dropped in a decade to $100. S-loaded Ohio sold many out of state.
Coal industry added western coal to its eastern and prospered. But historical lost of jobs in eastern coal mines continued.
Goals met at a cost less than expected. Clever engineering gets most of the credit for new, effective technologies: fluidized bed burners, scrubbers in combustion discharge stacks. Emission (allowance) trading also allowed flexibility to keep costs low.
Fuel switching was the unexpected event that kept cost low. Low-sulfur coal from Wyoming and Montana (& its 0.5% sulfur) produced automatic reduction over midwest coal (4-6% sulfur). As we return to midwest coal in the future, either future technological breakthru or added costs (financial or environmental) await.