For smell - a bit of Caramex in a dust mask/under the nose.

Actually, IIRC the medical grade masks will filter smaller particles than dust masks.

Activated charcoal needs to be "fresh" or freshly opened. Any moisture really detracts from the effectiveness.

Most neck scarves are made from fleece. Fleece, nylon, poly, etc are the things I'd LEAST want to wear. It burns/melts. Leather, cotton and wool will burn, but only at much higher temps.

I've always liked the idea of the evac-u-ate. But I'd still carry goggles and dust mask - the evac-u-ate would be great in situations where the heat/smoke/lack of O2 may be a problem, but if you use it for dust then you won't have it for the environments where the dust masks alone will not help.

IIRC CO and CO2 REPLACE O2. You cannot fix this with any type of filter.

Where are the firefighters here?