Clean-up of lead in household carpet and floor dust.

Methods to remove lead-containing dust were tested on carpets from homes of children with high blood lead and on new carpets artificially contaminated in the laboratory. The household carpets could not be cleaned effectively by repetitive vacuuming with HEPA-filtered cleaners. The lead concentration in the removed dust remained about the same from the initial cleaning (1 min/m2) to the final cleaning (total cleaning time of 10 min/m2). The lead loading on the surface of the carpets often increased during cleaning because vacuuming brought lead from deeper in the carpet to the surface. Over 95% of the total dust was removed from bare wooden floors by dry vacuuming (5 min/m2). For linoleum, more than 75% was removed by vacuuming for 5 min/m2. However, little was removed in vacuuming after the initial two minutes and about 20% was removed in a final wet-washing step. HEPA-vacuuming of the laboratory-contaminated carpets revealed that two of the commercially available vacuum cleaners tested were essentially equivalent and each removed significantly more dust than a third vacuum during a total cleaning time of 10 min/m2. Cleaning for 6 min/m2 was necessary to remove more than 70% of the embedded dust by the two more efficient vacuums. Cleaning efficiencies were about the same for short pile and sculptured carpets. It was concluded that it may be more practical to replace rather than clean carpets. HEPA-vacuum cleaning of carpets was shown to increase lead dust on the surface under some conditions.