NYC-WTC_000195194

NYC 9/11 Public Portal Document

W' Dioxin Before Cleaning Samples - Three pre-cleaning wipe samples were collected and analyzed for dioxin. The results indicate that there was dioxin present; however, the TEQ concentration for each sample was below the primary clearance criterion of 4 ng/m^.

w' Post P* Cleaning Samples - Four post-cleaning wipe samples were collected and analyzed for dioxin. The results indicate that the TEQ concentration for each sample was below the criterion of 4 ng/m^ and were detected at lower concentrations than in the pre-cleaning samples.

Gypsum Before Cleaning Samples - Pre-cleaning air samples were not collected. * «r Post Cleaning Samples - Two air samples were collected after the first cleaning. «r Gypsum was not detected above the detection limit in these samples.

Lead Before Cleaning Samples - Four micro vacuum samples and three wipe samples were collected. The results indicate that all four micro vacuum samples exceeded the comparison value. Two of the three wipe samples exceeded the primary clearance criterion of 25 pg/ft^. The third wipe sample was below the detection limit. The micro vacuum samples ranged in concentration from 69.8 pg/ft^ to 83.7 pg/ft^, and the wipe samples ranged from non-detect to 181 pg/ft^. <r Post P' Cleaning Samples - Two air samples, three micro vacuum samples, and four wipe samples were collected after the first cleaning. The two air samples were below the primary clearance criterion of 1.0 pg/m\ The results of the micro vacuum and wipe samples show that all samples met the comparison value or primary clearance criterion for lead after the first cleaning; however, three of the four wipe samples were qualified as * rejected due to field blank contamination, and one wipe sample was not analyzed because it was not received at the laboratory.

Post 2^ Cleaning Samples - While the study was underway, there was a revision from a background clearance criterion for lead in air of 0.1 pg/m’ to a health-based clearance criterion for lead in air of 1.0 pg/m\ The initial results were compared to the background clearance criterion which resulted in a decision to re-clean the dwelling and resample for lead in air. This also occurred in four other units and although these units were cleaned a second time and samples were collected after the second cleaning, the revised lead-in-air criterion actually negated the need for the second cleaning and sampling events. One air sample was collected and analyzed for lead. The result for this sample indicates that the concentration was below the primary clearance criterion of 1.0 pg/m \

Alpha-Quartz Before Cleaning Samples - Pre-cleaning air samples were not collected.

Post P' Cleaning Samples - Two air samples were collected after the first cleaning. All of the samples were below the detection limit.

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NYC-WTC_000195261