Contractors with brooms are a huge pet peeve of mine at a construction site. Seriously, WTF? You take all the dust and re-suspend as much of it as possible into the air?

Every construction site should have a HEPA-filtered vacuum with a filter bag. (The bagless kind is to be reserved for special cases that need it, and people should wear respirators when emptying it, TYVM.). Brooms are for non-vacuumable debris only, and subcontractors should be reminded of this regularly.