If your equipment doesn't have it already, I would make sure there's a "roof" over it that consists of a flat, dust-free, and relatively non-porous surface that hangs above the equipment which is made of a material that will easily withstand periodic dust removal with a disinfectant like 10% bleach (normal disinfectant bleach diluted 1:10 in water) or something like Spor-Klenz if you're worried about chlorine corrosion of the equipment. A roof will go a surprisingly long way towards preventing any contamination.

Then, I would make sure that you find a way to limit the room air currents towards the equipment. I've seen PCR machine heat exhaust vents contaminate sterile plates a few feet away by blowing air towards them as they were being poured. You can simply block the air physically, or if it's not a financial issue, get some of those little fan boxes that circulate air into UV light and a HEPA filter to suck floating dust away from the equipment. Just make sure they're set up so they're not pulling unfiltered air horizontally right across across open samples.

(I am assuming you mean a non-pathogenic yeast like Saccharomyces cerevisiae also, where you only really only have to worry about things getting into your cultures and not extensively about biosafety containment of the yeast itself.)

Alexandra Johnson thanks! these are really good tips. I might be able to rig something up. :D