Lead from paint chips, which you can see, and lead dust, which you can't always see, can be serious hazards. Peeling, chipping, chalking, or cracking lead-based paint is a hazard and needs immediate attention. Lead-based paint may also be a hazard when found on surfaces that children can chew or that get a lot of wear-and-tear. These areas include: Windows and window sills. Doors and door frames. Stairs, railings, and banisters. Porches and fences.
Lead dust can form when lead-based paint is dry scraped, dry sanded, or heated. Dust also forms when painted surfaces bump or rub together. Lead chips and dust can get on surfaces and objects that people touch. Settled lead dust can re-enter the air when people vacuum, sweep or walk through it. Lead in soil can be a hazard when children play in bare soil or when people bring soil into the house on their shoes.
Note: Lead-based paint that is in good condition is usually not a hazard. link