With our regrets for belaboring everyone - we're just presuming coal folks' interest in these matters we were exploring with Jamie.
So, y'all get the shotgun. 
In any case, we had earlier suggested that natural processes, primarily volcanism, render similar pollutants generated by coal use inconsequential - not that we shouldn't responsibly tend to them, especially since they might have material value for us.
As a start, we submit the attached:
Talk about pimples on an elephant's butt.
Should the link not open, there is a graph from the USGS which - if we read it correctly - illustrates that just one vent on just one of Hawaii's volcanoes sends more than 2,000 tons per day of SO2 into the atmosphere.
Actually, it might be one complete rift zone - but, still.
One island, one volcano, one rift zone.
Hang on while we compile some other data, data that we can compare to measured emissions from power plants.
And, we will be checking on data from other active areas - such as Iceland and the Phillipines.
As we start adding the numbers up, we believe that all the hyperventilation over all the coal-fired power plants' puffs from a toke on a Camel or Kool - relative to one volcano's burning up a whole Marsh-Wheeling Stogie - will begin to appear humorous. Not that we shouldn't be doing what we can.

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