NYC-WTC_000232959

NYC 9/11 Public Portal Document

ug/m',1 in inhalable dust. Mica and halite are not seen with the same frequency, but are detected in several air samples from lower Manhattan. Calcite, portlandite, mica, and halite are all detected in air samples taken in lower Manhattan, but not in air samples from the comparison areas above 59th Street (Table 11). Therefore, the airborne levels of calcite, portlandite, mica and halite appear to be higher in some air samples from lower Manhattan than in the samples from the comparison areas above 59th Street.

Gypsum was the most common mineral detected in air samples from lower Manhattan for all size fractions and was detected in 40 out of 114 respirable fraction (PM4) air samples at levels ranging from approximately 4 pg/mb-l 5 pg/m'J. Gypsum was estimated at 3 Lig/m\l 14 pg/m^J and detected less frequently in the PMIO (33 of 105) and PMIOO (24 of 101) size fractions, even though the detection limits for these fractions were lower. Gypsum was found in one of the PM2.5 samples, at approximately 3 pg/n?J. Across the size fractions, gypsum was detected in air samples taken in lower Manhattan at higher estimated levels than air samples taken from the comparison areas above 59th Street (up to 5 pg/m^J). Therefore, the airborne levels of gypsum seem to be higher in some air samples from lower Manhattan than the chosen comparison areas above 59th Street.

DISCUSSION

This section of the report will provide a more in-depth review of where the various materials were detected. In addition, the public health concerns potentially associated with these materials is also presented.

A. Discussion of Results

Settled surface dust samples obtained from lower Manhattan as part of this investigation contained materials consistent with debris from a building collapse. Both indoor and outdoor settled surface dust samples contained some amount of insulation material (asbestos, glass wool, and mineral wool), components of concrete (portlandite, calcite, and quartz), and components of other building materials (gypsum, mica, and halite). These materials were not present at the same levels in the four buildings above 59th Street sampled for comparison.

Asbestos levels in dust in the lower Manhattan area, ranging from <1% to 3.4%, were consistent with samples taken of outdoor material by EPA after the WTC collapse. SVF levels in the settled surface dust in lower Manhattan were higher than in the comparison areas above 59th Street, ranging from 1% to 72%. No data were available for SVF in lower Manhattan prior to this investigation. Analysis of archived dust samples collected after the WTC collapse by NIOSH, confirms the presence of SVF in bulk samples taken in lower Manhattan.

The minerals found in settled surface dust from residential buildings in lower Manhattan were consistent with minerals reported by the United States Geological Survey (USGS) for outdoor settled surface dust across lower Manhattan after the WTC collapse (9). Thirty-three dust, two concrete, and two steel insulation samples were analyzed by USGS,

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