[arugula]

That is also my main misgiving against doing so..... but at best it clogs easily and stops the fire breathing.

[2peasinapod]

saw dust in the air can burn quiet well

clickythingy 

if its in a "solid" state it will just smolder/burn,
if in doubt contact your local fire saftey officer for best info.

[Bluedave]

Throwing considerable amounts of any fine dust into a fire can cause an explosion if there is enough oxygen. I remember my Chemistry teacher (Mr Evans) blowing custard powder into a cardboard box with a naked flame in it and it popping like a good 'un - he told us that he had successfully blown up a piano using this method when he was a student - can't vouch for the validity of that but his experiment was certainly a success - bet he's been retired nowadays with all this health and safety malarkey!

Putting (rather than throwing) handfuls on shouldn't be a major problem - it might not be fine enough to explode anyway? I use my sawdust as micro kindling to start the fire with and then add larger bits of wood when it gets going. Sounds like you have a lot more sawdust than me though.

[hamstergbert]

Dust can be an explosive risk if suspended in air, and that includes sawdust especially if of a fine particulate size. 

Generally the bigger the particulate size the harder it is to initiate a self-propogating explosive combustion (and the harder it is to achieve a particulate suspension in air).
 
When sawdust etc is in a pile and moved around in shovelfuls or whatever, the amount of air between the particles is likely to be insufficient to combust more than a very small proportion of the wood material even if you can get a detonation source going.

 (We used to do the candle in a box with a pipe to blow a spoonful of flour up from a funnel inside the box with varying degrees of explosive success).

A bit of entertainment here

[Spana]

Blimey :blink: