The biggest chance of starting a fire isn’t from dust, but from finishing products. Needless to say volitiles in finishing products could easily combust, but the most easily overlooked item is steel wool. As a kid my older brother showed me that he could hold his hand right in that plum of sparks without getting burned. But if you want to experiment, just lay half a pad of 0000 on something fireproof and send some of those sparks into it and watch what happens. It spreads outward and gets really hot enough to combust other things around it.