NYC 9/11 Public Portal Document
Lead
Before Cleaning Samples - Six micro vacuum samples and four wipe samples were
collected. The results indicate that lead was detected in all six of the micro vacuum
samples at concentrations above the comparison value of 25 pg/ft^ ranging from 26.2
pg/ft^ to 83.5 pg/ft^. One of the four wipe samples exceeded the primary clearance
criterion of 25 pg/ft^ with a concentration of 169 pg/ft^.
Post Cleaning Samples - Two air samples, six 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 lab blank contamination.
The results of the micro vacuum and wipe samples show that all but one wipe sample (66
pg/ft2) met the comparison value or primary clearance criterion for lead.
Post 2"*^ Cleaning Samples - One air sample and one wipe sample were collected after the
second cleaning. Both sample results were below their respective clearance criterion.
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
samples were below the detection limit.
Calcite
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. Since all of the samples were below the
detection limit after the first cleaning, no additional samples were collected for analysis of
calcite.
Cristobalite
Before Cleaning Samples - Pre-cleaning air samples were not collected.
Post J" Cleaning Samples - Two air samples were collected after the first cleaning. All of
the samples were below the detection limit. Because all of the samples were below the
detection limit after the first cleaning, no additional samples were collected for analysis of
cristobalite.
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. Because all of the samples were below the
detection limit after the first cleaning, no additional samples were collected for analysis of
tridymite.
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NYC-WTC_000145766
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