Slide 6 of 28
Notes:
For many years, the standard approach to air pollution from a utility, plant, or other source of noxious vapors, was to build a taller smoke stack. This kept the plume away from the ground until it had become sufficiently diluted to be tolerable.
This approach could be dubbed, "Out of sight, out of mind." Though straightforward and easily implemented as part of the cost of doing business for the utility responsible, it ignored the obvious point that emissions from many different utilities accumulate downwind where collectively they might be far from tolerable.