One of the most overlooked part of a dust collection system is that all parts of the dust collector path must be GROUNDED.
Mixing air and fine dust, when missing one component is safe.
Ignition from a static discharge (ESD) (easily found when not grounded) can cause a very nasty fire and in extreme cases a moderate explosion.
Example: Rubbing two styro coffee cups together can generate nearly a thousand volts of instantaneous ESD, more commonly exhibited as a spark. Think of the results.
These dangers are easily found when air and fine particulate of any kind are mixed together.