VOC sampling locations table for Ground Zero area, Jan 2002

NYC 9/11 Public Portal Document

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However, since only a minority of the sampling locations (6) had PCM counts above backgroimd, and hence were analyzed by TEM; results are not conclusive regarding the potential for low levels of airborne asbestos (i. e., at levels < 0.003 free — fibers meeting criteria for optical visibility). In this regard it should be noted that the specific residences that had detectable asbestos in indoor dust did not have elevated airborne PCM levels and TEM data were not collected for these residences. Note that when conditions allowed the residential sampling utilized an "aggressive" methodology involving the operation of the vacuum exhaust, used for settled dust sample collection, to stir the air. Additionally, evidence of elevated asbestos levels was not found in air samples collected in common areas of the apartment buildings or in adjoining outdoor areas.

The NYCDOHMH/ATSDR Final report also included data on synthetic vitreous fibers (SVF or fibrous glass) concentrations in indoor and outdoor dust samples at the same residential locations. SVF (PLM analysis) was detected in a larger number of indoor dust samples (26 of 57 or 46%) and at higher concentrations (range 2-35%) than asbestos. In outdoor dust at these properties, SVF was detected in 11 of 14 (79%) of samples (concentration range 15 - 72%). As with asbestos, the study did not provide evidence of airborne SVF above background levels in indoor air samples collected at the residences in lower Manhattan. PCM measurements will detect SVF, and in those locations where air samples had total PCM fibers exceeding background. Scanning Electron Microscopy (SEM) also reexamined filters for SVF. While such fibers were detectable in two samples, all samples were below 0.001 free.

Air and settled surface dust samples were also analyzed for mineral components of concrete (quartz, calcite, and portlandite) and mineral component of building wallboard (gypsum, mica, and halite). The X-ray diffraction analysis (XRD) analysis for crystalline minerals in air and settled surface dust is reported by NYCDOHMH/ATSDR as semiquantitative (labeled with a “J”). Air sampling for minerals detected quartz and other building-related materials in lower Manhattan. The other forms of crystalline silica were not detected in any air samples except for a one-time detection of cristobalite. The estimated concentrations of these minerals in air were low. In some locations, mineral components of concrete (quartz [3-19 ug/m^J], calcite [ND-14 ug/m’J], and portlandite [ND-95 gg/m^J]) and mineral components of building wallboard (gypsum [4-15 gg/m’j] and mica [ND-43 gg/m^J]) were detected in air samples at higher estimated levels in lower Manhattan residential areas than in samples taken at comparison residential areas above 59th Street (quartz up to 6 gg/m^J, calcite up to 6 gg/m’J, portlandite up to 30 gg/m^J, gypsum up to 6 gg/m’J, and mica up to 17 gg/m^J). Quartz, calcite, portlandite and gypsum appear to make up a higher percentage of dust in some buildings in lower Manhattan when compared to settled surface dust samples from buildings above 59th Street. Quartz was detected up to an estimated 31 %J versus up to 2%J found in the comparison areas above 59th Street. Neither cristobalite nor tridymite was detected in any of the settled surface dust samples. Similarly gypsum was found at a maximum estimated concentration of 30%J in settled surface dust, higher than the 4%J estimated in the comparison areas above 59th Street. Calcite and portlandite had maximum concentrations of 21%J and 8%J respectively. At lower Manhattan locations sampled, quartz was detected in 81% of common areas and 53% of residences. Gypsum was seen in 88% of common areas and 79% of residences. Minerals were

DRAFT~DO NOT QUOTE OR CITE 129 October 2002

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