NYC-WTC_000195194

NYC 9/11 Public Portal Document

The results of the five wipe samples indicate that asbestos was present in all of the samples, but generally at lower concentrations than those observed before cleaning.

Post 2"“^ Cleaning Samples - Four post-cleaning air samples were collected for asbestos. These samples were analyzed using PCM, TEM AHERA, and PCMe. The results of the PCM analysis were below the secondary numeric criterion of 0.01 f/cc. One sample was below the detection limit. The TEM AHERA results were all below the detection limit. The PCMe results were also all below the primary clearance criterion of 0.0009 S/cc. This «r indicates that the cleaning techniques were effective at reducing the particulate matter, which allowed valid air samples to be collected and analyzed. w Dio?dn Before Cleaning Samples - Four pre-cleaning wipe samples were collected and analyzed for dioxin. The results indicate that dioxin was present; however, the TEQ concentration for each sample was below the primary clearance criterion of 4 ng/m^.

Post P‘ Cleaning Samples - Four post-cleaning wipe samples were collected and analyzed for dioxin. The results indicate that dioxin was present; however, the TEQ concentration for each sample was below the primary clearance criterion of 4 ng/m^ and were detected at lower concentrations than in the pre-cleaning samples. This indicates that the cleaning techniques were effective in reducing dioxin concentrations. w * 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 of 0.008 mg/m’ in the air samples.

Lead Before Cleaning Samples - Three micro vacuum samples and four wipe samples were collected. One of the three micro vacuum samples was above the comparison value. The other two results were below the detection limit. The results indicate lead was present in two of the four wipe samples at concentrations above the primary clearance criterion of 25 4* pg/ft2. The micro vacuum samples exceeded the comparison value at 50.7 pg/ft^ and the two wipe samples exceeded the primary clearance criterion at 112 pg/ft^ and 201 pg/ft^.

* 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 but were qualified as rejected due to field blank contamination. The results of the micro vacuum and wipe samples show that while one of the micro vacuum (qualified as rejected) and two of the wipes samples exceeded the detection limit, all samples met the comparison value and the primary clearance criterion for lead after the first cleaning. Therefore, additional samples were not collected for analysis of lead.

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

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NYC-WTC_000195251