Properly maintained fires and chimneys are very safe but a Carbon Monoxide alarm is there to warn you if something goes wrong.
Sometimes it's ignorance, sometimes it's accidental and sometimes it's deliberate.
If you try to burn sawdust on your stove or open fire you'll be disappointed. It will tend to smother a nice fire and produce lots and lots of smoke. That's a pity if you have lot's of waste sawdust.
It’s barbecue time right now so here are some yum-tastic tips on how to light a barbecue