IMO we have a similar situation where Glenn Reynolds cites big reductions in atmospheric SO2 and other substances during last year's blackout in the Ohio Valley.
So what does this tell us? That power plants are particularly filthy? Or that the atmosphere recovers rapidly from such influxes?
Always be suspicious when numbers are given in percentages. What is important is whether the typical numbers were dangerous. Were they? We can't tell from GR's cite.
At the end we read:
the spectacular overnight improvements in air quality "may result from underestimation of emission from power plants, inaccurate representation of power plant effluent in emission models or unaccounted-for atomospheric chemical reactions." (Marufu et al., Geophysical Research Letters, vol 31, L13106, 2004.)There could be other issues too, such as weather in the vicinity - if winds came from a different direction or there was a good rain the results could be skewed significantly also.
So perhaps the most appropriate conclusion to reach is that the atmospheric scientists are wrong again. Remember that the next time we hear about anthropogenic global warming.
Having once worked in TVA country not too far from the Widows Creek generating station, I heard the stories. Supposedly things were done differently at night when it was harder to see the smoke, etc. And experienced dirt-burner engineers know better than to drive nice cars to work - get a beater to absorb the abuse from the pollution.
Things have changed since then so perhaps I'm too harsh. And I have something of a conflict of interest in that I worked in the nuclear power industry for 10 years before I was starved out in the early 1990's. I was one of those guys who'd remind people that in normal operation a coal plant released more radioactive substances into the environment than a nuclear power plant does.
But I'm also one of those guys who knows our alternatives and has worked in the utility industry. I stand to profit from energy technologies regardless of the source of the power or whether demand goes up or down. So while I won't claim I'm a savant on energy issues, I'm more aware of them than the average citizen.
Later GR writes "I've always felt -- as many people who live in TVA country do -- that burning coal to generate power is an absolutely filthy and destructive habit." This is the guy who raves about nanotech and other cutting-edge technologies. Who's to say that we won't someday find technologies for extracting the energy from coal economically without throwing away potentially useful constituents like the sulfur that currently gets dumped into the atmosphere as SO2?
In fact, the cure might involve nanotech....