NYC 9/11 Public Portal Document
Post Cleaning Samples - Two air samples were coUected after the second cleaning.
Both samples detected concentrations below the primary clearance criterion.
Alpha-Quartz
Before Cleaning Samples - Pre-cleaning air samples were not coUected.
Post P' Cleaning Samples - Two air samples were coUected after the first cleaning. AU
samples were below the detection Umit.
Calcite
Before Cleaning Samples - Pre-cleaning air samples were not coUected.
Post Cleaning Samples - Two air samples were collected after the first cleaning. AU of
the samples were below the detection Umit. Because all of the samples were below the
detection Umit 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 coUected after the first cleaning. AU of
the samples were below the detection Umit. Since 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 coUected.
Post deeming Samples - Two air samples were collected after the first cleaning. AU 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
tridymite.
MMVF
Before Cleaning Samples - Three pre-cleaning wipe samples were coUected. The three
wipe samples detected MMVF in concentrations from 343.39 S/L to 744.01 S/L. This
indicates that MMVF was present prior to cleaning.
Post J" Cleaning Samples - Three air samples and five wipe samples were coUected after
the first cleaning. AU of the air sample results indicate that MMVF was present at levels
below the primary clearance criterion of 10 S/L. AU of the wipe sample results were
above the detection Umit and at concentrations similar or lower than the pre-cleaning
samples.
Post Cleaning - Five air samples were collected after the second cleaning. Four of the
five samples were below the primary clearance criterion of 10 S/L. However, one sample
exceeded the primary clearance criterion at 91.796 S/L. This value was further evaluated
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NYC-WTC_000145751
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