You can choke on particulates from heavy smoke, but really, it's the toxic gasses that will render you unconscious very quickly. Within a few breaths if enough gasses are present. For a smoke hood, I would prefer something that filtered carbon monoxide (and by default, it should filter out lots of other nasty gasses). As I have in the past, I would recommend the Safe Escape Smoke Hood. It seems to be the best balance of performance and cost.

A smaller option that might be easier to have on or near you would be the Xcaper Mask. Only covers your mouth and nose, but it's more compact than a full hood and still filters CO.

Don't toss that N-95, though. The only real situations where I have had to use an N-95 is when wildfire smoke was in the area but it certainly helped.

How high up is your office?