NYC 9/11 Public Portal Document
Alpha-Quartz
Before Cleaning Samples - Pre-cleaning air samples were not collected.
Post Cleaning Samples - Two air samples were collected after the first cleaning. The
two air samples were below the detection limit. Because the samples were below the
detection limits after the first cleaning, no additional samples were collected for analysis of
alpha-quartz.
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. Because 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 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
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.
MMVF
Before Cleaning Samples - Two pre-cleaning air samples and three pre-cleaning wipe
samples were collected. One of the two air samples was above the primary clearance
criterion of 10 S/L and the other air sample was above the detection limit. The results for
all three of the wipe samples indicate that MMVF was above the detection limit. This
indicates that MMVF was present in the unit prior to cleaning.
Post f* 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, all three were below the primary clearance criterion of 10 SIL. The results of
the five wipe samples indicate that three of the five samples were below the detection limit
and the remaining two samples were at the detection limit. Although MMVF was still
present after the first cleaning, the concentrations detected were much lower than the pre
cleaning samples. There is not a clearance criterion for MMVF in settled dust. Because
the air samples were below the primary clearance criterion and the MMVF in settled dust
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NYC-WTC_000145748
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