Dan, interesting post... more evidence of the sub micron particles being the culprit. thanks for sharing.

Another issue that has really opened my eyes to this dust problem is...... workers in grain plants (corn, wheat, etc) also suffer terrible (often fatal) health problems with fine dust. One would suspect, that since this dust is from foods we eat on a regular basis, their dust would not be toxic.

Therefore, it stands to reason, wood dust, specially MDF has the potential to be as dangerous, or probably more dangerous, as wood is not an edible food. It also seems, based on the OP's comments of Bill P's results, that breathing polluted outside air from living in industrious areas will never have anywhere near the fine dust concentration as working around wood power tools, as the dust concentration is diluted many million times by the huge air mass in our atmosphere. I found this part of the OP's comments very interesting....i.e., by simply opening the garage, the particle concentrations were drastically reduced, demonstrating how quickly fine dust particles will dilute, if given the opportunity.

I am curious of Bill P's comments on this.... and when this thread comes near a close, it would be nice if Bill posts a "hit list" of Dust Safety procedures, in order of priority, in order of cost, etc.