Volume 8, Issue 8 (September 2011)
Improving the Confidence Level in Lead Clearance Examination Results through Modifications to Dust Sampling Protocols
Multiple pre-cleaned, four-room residential containments were each subjected to a single high-dust generating activity involving lead-based paint. After dust generation, a geometric wipe sampling grid was used, with a target of 8 interior and 8 perimeter samples in each room, to assess dust-lead on the floors. The containment was then cleaned using the “High Efficiency Particulate Air (HEPA) vacuum/3-bucket wet-mop/HEPA vacuum” procedure found in the U.S. Dept. of Housing and Urban Development Guidelines. Post-cleaning (clearance) floor wipe samples were then taken at side-by-side locations to the pre-cleaning samples. It was found that:  floor dust-lead along the perimeters of rooms was three times more difficult to clean than dust-lead from the interiors of the rooms;  post-cleaning dust-lead loadings tended to be higher along the perimeters of the rooms than in the interiors of the rooms such that clearance failure was much more likely for individual floor samples collected along the perimeters; and  four-wipe composite sampling within each room (two randomly selected from the perimeter and two randomly selected from the interior) provided a very reliable method for detecting clearance failure (99% or greater) versus a randomly selected single wipe sample per room (50% or less).