Instead of worrying about explosion proof exhaust fans, why not just pressurize a paint booth using a normal fan, and have a series of filters leading to an exhaust vent?
No longer is there risk of paint/solvent vapours ever reaching the fan, or any moving parts, for that matter. The filters would take care of much of the particulates before it can be released into the atmosphere.
I think it would be a cheaper and simpler alternative to hunting down explosion-proof fans, or doing the whole sealed/belt driven affair.
What say you all?