If you use a ShopVac to vent, I would suggest purchasing the fine dust collection bags used for things like sanding drywall. The dust is fine enough to bypass your filters and will exit through the exhaust on the vacuum.
Let's just say I will be thinking about this as I spend all weekend claybarring my '61 Studebaker Hawk to get all of the beadblasting dust out of paint.
Seeing as how the dust is this fine, a mask or respirator probably wouldn't be a bad investment.
Lee
