Is exposed Roxul insulation safe?
Roxul is our #1 choice of insulation in exposed areas.


It is non-flammable.
After installation it releases very little dust comparatively.   
The dust released has really no harmful effects other than slight irritation.
It molds and conforms stronger than fiberglass and other roll insulation.  Just make your cuts bigger than the area and compact the material in.
It has little to no smell.
Mice/Rats don't like it.


I personally have exposed ROXUL in my laundry room which is the only unfinished room in my house.  It is jammed into ever joist crevice on outside walls.  It also is in at least 30-40 basements I have finished.  It is the best performing insulation I have used - my laundry room is an oven in the winter and was cool with fiberglass sheets.  I would also suggest that you do not put up a vapor barrier unless the ROXUL is below human height - and really unless you are in a very cold climate you should not be insulating that low on a basement.  For basement windows it is the perfect choice.

(Not affiliated with the company at all nor a fanboy.  There are just a few products out there that beat the competition by a lot and I recognize that.  Mike Holme's uses it on everything too.)