Test for Lead
Most lead-paint poisoning results from exposure to lead dust. Even if you don't see any peeling paint, lead dust might still be present. Old doors and windows have painted parts that rub together and create dust, or there might be small amounts still present from a previous remodeling project. Testing will determine if you have a lead hazard. Various types of test kits are available for about $10. They're all a little different, so read and follow the directions carefully. Some come with everything you need to collect and send samples to a lab for analysis, for which you pay a separate fee ($15 to $20 per sample). Others, like 3M's LeadCheck swabs shown above, don't require lab testing. You just squeeze a swab while rubbing it onto a painted surface. If the tip of the swab turns pink or red, you've got lead.
Seal Off Your Work Area
Remove all furniture and rugs in the room you're about to work in and cover floors with 6-mil polyethylene (poly) sheeting. Use duct tape to secure it to the floor tight to walls and at least 5 ft. beyond the room you're working in. Avoid taping it to baseboards or other trim if you're worried about damaging the paint. Turn off the furnace and then cover supply and return registers with poly and tape. Keep windows closed to prevent dust and chips from blowing around, and cover and tape off doors and other openings to keep dust contained to your work area.