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Suppose you sand away with your ROS or belt sander and
collect a nice large volume of dust. Then when you are
emptying your dust collector you drop it and the dust you
created over the course of several hours all goes airborne
at once.

Now, that could make a nice impressive fireball--but only if
there is an ignition source like a pilot light or a spark from
an electric motor. A static spark may not be enough, but
static sparks are not the only ignition sources.

Any documented cases of that happening?