Well well well. Here i come.
My workshop heater is here
http://donkey32.proboards.com/thread/1817/starting-build-220mm-rocket-double
No problem so far. As michael said, if it gets dusty enough to be explosive. Your lungs will be caked!
So in my workshop, i use a cyclone loosely based on Bill Pentz plans.
http://billpentz.com/woodworking/cyclone/cyclone_plan.cfm
It is worth reading the whole site thoroughly.
My cyclone is a push through. As it's the easiest to use with sawdust bags. The latest addition is two nanoweb filters. With a filtering surface of 60m² .
Future plan is to make also a high volume workshop air cleaner. You know like those little ceiling mounted units.
But something proper with hepa filters or something along the lines.
And for the whole workshop air cleaner, i will follow the solution of Mario Proulx.
http://www.mimf.com/phpbb/viewtopic.php?f=12&t=2764
You might have to register to view the aulde discussion on his workshop filtering.
Here's a few pic of the cyclone in it's curent state.