Sealing off this cold-air return duct ensures that job-site dust does not get blown throughout the house.
To make an effective airlock — one that lets people in without letting dust out — use two layers of 6-mil plastic. The first layer should be a few inches longer than the doorway and about a foot wider (so there's plenty of slack in the middle). After duct-taping all sides of the plastic, cut a slit down the middle, stopping 6 inches short of the top and bottom (reinforce the ends of the slit with duct tape). Place the second layer of plastic over the first one and tape it to the top of the door.
A half-face respirator with purple (HEPA) filter cartridges is standard equipment for workers who routinely disturb lead paint (the extra-thick purple and yellow cartridges offer additional protection from lead or chemical fumes). Remodelers, electricians, and other workers who don’t disturb lead very often can wear a comfortable N100 disposable respirator.
After the dirty work is done, all surfaces and crevices should be slowly and thoroughly vacuumed with a HEPA vac.
Swabbing a representative floor sample and sending it to a testing service (most can get you the results within 24 hours) is the way to know for sure that you’ve cleaned up all the lead.
For a job that might disturb only a small amount of lead paint, you just need to cover the floor with a sheet of 6-mil plastic that extends 5 feet away from the work area. Plastic shoe covers keep dust off and improve traction on the slippery surface.