NYC-WTC_000195194

NYC 9/11 Public Portal Document

Post Cleaning - Four air samples were collected for asbestos. The samples could not be analyzed due to overloading of particulate matter on the filters. Therefore, a third cleaning was conducted using a more aggressive cleaning method: a commercial HEP A vacuum and an AFD.

Post 3^ Cleaning - Six air samples were collected for asbestos after the third cleaning. The samples were analyzed for PCM, TEM AHERA, and PCMe. The results of the PCM analysis indicate that three of the six samples were below the detection limit. The remaining three samples were above the detection limit but below the secondary numeric criterion of 0.01 ftcc. The TEM AHERA results indicate that all six samples were below the detection limit. The PCMe results also indicate that all six samples were below the detection limit. This suggests that the cleaning techniques used for the third cleaning were effective at reducing the particulate matter to levels that permitted valid air samples to be collected and analyzed, with the results indicating that all six samples were below the primary clearance criterion of 0.0009 S/cc.

Dioxin Before Cleaning Samples - Three pre-cleaning wipe samples were collected and analyzed for dioxin. The results indicate that dioxin was present and that the TEQ concentration for one of the three samples was above the primary clearance criterion of 4 ng/m^.

Post P‘ Cleaning Samples - Four post-cleaning samples were collected and analyzed for dioxin. The results indicate that dioxin was present; however, the TEQ concentrations were below the primary clearance criterion of 4 ng/nr. This indicates that the cleaning techniques used were effective at reducing the pre-cleaning concentrations of dioxin.

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

Post P‘ Cleaning Samples - Two air samples were collected after the first cleaning. Gypsum was not detected above the detection limit in the air samples.

Lead Before Cleaning Samples - Four micro vacuum samples and three wipe samples were collected. Lead was detected in all four micro vacuum samples at concentrations above the comparison value. Two of the three wipe samples detected concentrations above the primary clearance criterion of 25 pg/fV. The micro vacuum samples exceeded the comparison value in a range of 39.4 pg/ft^ to 135 pg/ft^, and the two wipe samples exceeded the primary clearance criterion at 48.7 pg/ft^ and 750 pg/ft^. This indicates that lead was present prior to cleaning.

Post P‘ Cleaning Samples - Two air samples, four micro vacuum samples, and four wipe samples were collected after the first cleaning. The two air samples were below the primary clearance criterion. The results of the micro vacuum and wipe samples show that all but one micro vacuum sample (26.9 pg/ft^) met the comparison value or primary clearance criterion for lead.

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