NYC-WTC_000195194

NYC 9/11 Public Portal Document

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primary clearance criterion. Since the primary clearance criterion was met for lead after the first cleaning, no additional cleaning was necessary.

Post 2"“^ Cleaning Sampling - Because the cleaning was conducted prior to the establishment of a risk based cleanup level for lead in air, this unit was re-cleaned in an effort to meet the initially established clearance criterion . Sampling results following the second cleaning indicated levels below the primary clearance criterion. «r

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.

«r Calcite Before Cleaning Samples - Pre-cleaning air samples were not collected. w

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

Cristobalite Before Cleaning Samples - Pre-cleaning air samples were not collected. w Post P‘ Cleaning Samples - Two air samples were collected after the first cleaning. All of the samples were below the detection limit.

Tridymite 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. 4»

MMVF Before Cleaning Samples - Four pre-cleaning wipe samples collected. All four samples had MMVF detected above the detection limit.

Post P‘ Cleaning Samples - Three air samples and five wipe samples were collected after the first cleaning. The results for the three air samples indicate that MMVF was present; «■* however, both samples were below the primary clearance criterion of 10 S/L. The results of the five wipe samples indicate that MMVF was still present after the first cleaning; w however, the concentrations detected were generally lower than the pre-cleaning samples. There is not a clearance criterion for MMVF in settled dust.

PAH Before Cleaning Samples - Four pre-cleaning wipe samples were collected. All four samples were below the detection limit and the TEF for each sample was below the primary clearance criterion.

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