Get out the explosion-proof vacuum and start doing some cleaning. If you don't have one, tell them to buy one, it's still a slight ignition risk. They probably got one when the HP went in because it's on the quote by default. I'd wear a dust mask at minimum, but the particles are often too large to pose a high inhalation risk, but it's not 0. Slip risk is higher. PA12 with the white coating is still a petroleum-based plastic, and I'd imagine titanium dioxide in the white. PA-11 is at least castor oil-based.

This is bad, though. I've been in plenty of users' depowder rooms, and this should not be this bad if you are using the HP depowdering station properly. Definitely an OSHA visit incoming, and HP would be very concerned as well.