NYC-WTC_000232959

NYC 9/11 Public Portal Document

fiber counts greater than comparison areas above 59th Street were not elevated due to either asbestos or SVF fibers.

There were 15 out of the 83 (18%) indoor areas in lower Manhattan with measurable asbestos in the settled surface dust, 10 residences and 5 common areas (Table 9). Nine of these residences were sampled aggressively (the ah’ exhaust of the vacuum used for settled dust sampling was used to stir up all dust into the air before an air sample was taken). Four of these aggressively sampled residences had measurable fiber levels in air ranging from 0.001 f/cc to 0.003 f/cc. One residence was occupied and could not be aggressively sampled. Air sampling at that location indicated <0.001 f/cc by PCM analysis. Because the levels found were within the range measured in the comparison areas above 59th Street, no TEM or SEM re-analysis was performed on these air samples. Therefore the composition of these fibers is unknown (i.e., asbestos, SVF, cellulose).

None of the common areas were aggressively sampled because all of these areas were open to the public. Of the five common areas with some asbestos in the dust, three had measurable levels of fiber in the air ranging from 0.001 f/cc to 0.002 f/cc. One area in building 5 where there was not enough settled surface dust to sample had an airborne fiber count of 0.002 f/cc. No TEM or SEM re-analysis was performed on these air samples, and the composition of these fibers is unknown (i.e., asbestos, SVF, cellulose).

b. Outdoor Air

Six of the 14 lower Manhattan outdoor locations sampled had detectable levels of asbestos in the settled surface dust, indicating a potential in these locations for asbestos fibers to become airborne. Air sampling indicates three of the locations did not have detectable fibers in the air (Table 9). The air samples from buildings 1, 2, and 5 did have fibers detected at levels from 0.001 f/cc to 0.003 f/cc. Of the 15 locations where no settled surface dust samples were taken, the majority of the results showed <0.001 f/cc in the air, with only 4 samples reported at the detection limit of 0.001 f/cc. Because the levels found were within the range measured in the comparison areas above 59th Street, no TEM or SEM re-analysis was performed on these air samples, and the composition of these fibers is unknown (i.e., asbestos, SVF, cellulose).

2. Minerals in Air

Air samples of different particulate sizes, representing inhalable (PM 100), thoracic (PM 10), and respirable (PM4 and PM2.5) fractions were collected in selected building locations. Not all size fractions were collected at every location. The samples were analyzed by XRD for the same crystalline minerals seen in the settled surface dust samples. Each of the four size fractions was collected with a separate sampling device. The PMIOO fraction collected particles with an aerodynamic diameter of 100 microns and lower. The PM 10 fraction collected particles with an aerodynamic diameter of 10 microns and lower and so on. The results reported here are expressed as the mass of mineral per unit volume of air or micrograms per cubic meter of air (ug/m' ). Quantification of the minerals is not exact due to variations in particle size as compared to the particle size used in the standard

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