Given you have a clean hose (so you don't spew dust from a dirty one) and a CT-SYS at hand you could put it into the blower configuration and use it to suck in air from the outside an push it into the room. This will also have the upside that the added air had been filtered and most likely will be cleaner (regarding dust) than one you would get from a fan or open windows.Why use a CT-SYS or any other vac in blower mode?
Googles and a mask with filters matching what you do is a must nevertheless, as is removal of all ignition sources that could spark you into oblivion.
My work history contains time inside environments where a slight spark could have brought a fair chance of a whole building spontaneously vanishing. The demonstration (basically
with a bigger
baloon to really
drive home the point) given to me at training was impressive enough for me to never again taking any
chances when it comes to ignition of flammable gas / air mixes (which most solvents for spraying will turn into when evaporating and while spraying).
Might sound a bit over-cautious, but since then I simply don't operate any non-EX gear in such environments... which lead to the reasoning to have the vac itself in a non-contaminated area where it can run safely.