Professional companies concerned about dust minimization may also (depending on the circumstance) erect “zip walls”, and some with zippers for ease of access to contain any extraneous dust to just the workspace. Some times it is not practical because of how the rooms are built, but more so than not we use them.
A zip wall is an artificial wall of plastic that is erected to seal off a wall space. Some times they are full size walls, and some are half walls. When needed the zippers are installed to allow the refinishing team access to the work area, and also gives ease of access to the homeowner while the work is being done.
Our company also often uses Hepa Filtration- “Air Scrubbers” while we are sanding. This forces the air thru the airscrubber in the entire air space several times a day. This technology is utilized in medical applications, clean room environments, and restoration and structural drying and decontaminating applications.
Either or both technologies are extra measures taken to assure a cleaner refinishing process. Likewise when these systems are part of the refinishing process they are brought on board at an additional cost, both as an investment of the technology, and the extra labor needed to set it up and utilize it.
When vetting out a refinishing company it would be good to ask if the use this technology. If they do, you most likely will find their estimate to be similar to the other competent refinishing companies, and far different from the cheap estimates provided by the shoddy refinishers that flood this industry.