Anything to do with dump out bags and dirt clouds, everyone that has a bagless vacuum already is exposed to. It's the same exact thing. If you are that sensitive to dirt then you should not own a dump bag vacuum, or a bagless vacuum. If you do, just dump the dirt outside in the can. Totally a non-issue.
The reason dump bags are used in janitorial equipment is the amount of carpet they have to vacuum every single day. If they used paper bags, those bags would fill up within an hour or two, or get punctured, and the retail price of constantly ordering new packages of bags in bulk would be extremely expensive and far surpass the entire purchase price of the vacuum in due time. Commercial buildings will have enormous air filtration HVAC systems anyway, and with such a large square footage any dust spreading out is nothing to even care about.