Dust, Soil, and Water Sampling Protocols
Dust wipes
Dust is sampled with a pre-moistened wipe over a measured area - a standard template (typically 1 ft² on floors, smaller defined areas on interior sills and window troughs/wells). One wipe per distinct surface per room, with the sample area traced and recorded. Do not composite across rooms: floor, sill, and trough wipe results are compared individually to clearance or hazard standards, and compositing destroys the comparison. Keep gloves fresh, avoid cross-contamination, and avoid pre-cleaning the surface being tested.
Soil
Collect from bare soil, typically at drip lines and play areas. Composite sampling within a defined area (e.g., a set of subsamples from one yard) is acceptable practice for characterization, but clearance-type decisions require the protocol's specified sampling. Compare to hazard standards for bare soil in play areas versus other bare soil.
Water
First-draw sampling: a standing sample after a defined stagnation period (commonly 6–18 hours) from a tap not used during that period, taken before any other water use in the home. Flushing beforehand invalidates the lead result by diluting the sample.
Laboratory QA/QC
Use an accredited laboratory, maintain chain of custody, and expect method blanks, field blanks, matrix spikes, and duplicates. Wipe results are reported in µg/ft² (or µg/100 cm²) - watch unit conversions, a classic trap. Compare results to the applicable clearance standard (post-abatement clearance differs from the hazard-identification standards used in risk assessment; do not substitute one for the other).
Rule of thumb
Match the sampling design to the decision being made. Clearance sampling happens after cleanup and compares to clearance criteria; hazard assessment sampling compares to hazard standards; always record exact area, location, and surface type so the number is interpretable.