-MIKE- writes:
I can't even imagine a normal woodworking scenario in which that high
a concentration of wood dust could occur.

The linked report had a suspect cause: wood flour collected in hidden
spaces, something else went FOOM (like a small contained bit of wood
flour) and that blew all the other wood flour up into the air in a
contained space, starting a chain reaction.

Granted, this is rare in a home shop, but the focus of the report was a
commercial building that actually exploded, so it's not *impossible*.