Lead risk in New York, building by building.

A neighborhood risk map tells you which areas to worry about. This map goes further and shows you the individual buildings, and which ones to visit first. Below is a real example, built from public data, for one square mile of the South Bronx. Each dot is a residential building, colored by the decade it was built. Older buildings are far more likely to contain lead paint, so the age of a building is a strong first guess at where the hazards are.