Lead hides in the parts of a house that move

Lead-based paint was restricted for residential use in 1978, and the restriction did not remove what was already on the walls. The older the building, the more likely lead paint is present, often under later coats. Renovation, sanding and repainting disturb those layers, and fine lead dust settles on floors and sills where it is easily picked up.

Friction and impact surfaces: window sashes, sills and troughs, door edges and jambs, stair treads, painted floors and railings. Exterior paint can shed into the soil along the drip line. In older plumbing, lead can be present in service lines, solder and brass fittings, which is a water question rather than a paint question.

Paint chips are taken through all layers to the substrate. Dust wipes are taken over a measured area on floors, sills and troughs, so the laboratory can report loading. Water samples may be first-draw or flushed depending on the question. Samples are logged by location and sent to an independent laboratory under chain of custody.

Color-change swabs can flag a surface worth sampling, but they are a screening tool and can give false positives and false negatives - for example, when the swab never reaches an older layer under a modern topcoat. A laboratory result reports what was in the sample against a method.

Avoid making dust: do not dry-sand, heat-strip or scrape suspect paint. Wet-clean hard surfaces rather than sweeping, and keep children away from chipping paint and the soil along old painted siding.

We test; we do not abate. Health questions, including blood lead testing, belong to a physician.