If it's just solder fumes, a standard filter medium would be sufficient.
FWIW, true commercial solder fume extraction uses media rated for 0.3um particle filtration, but I suspect 0.5um will be quite sufficient. Bbetter than the activated carbon foam in front of a fan based units at any rate.
The carbon filter adds gas extraction (think solvent fumes, such as acetone, xylene, ...). So if you use a
lot of liquid flux and adhesives in an enclosed space for example, the carbon filter would be called for. You could see if the stuff for window air conditioners will work to add that to standard filters (easy to find an inexpensive as well
).