NYC-WTC_000199812

NYC 9/11 Public Portal Document

Street was approximately 0.018% by weight, and the concentration in the sample collected from the roof outside the Sth Floor loft at 45 Warren Street was approximately 0.021% by weight. At 250 South End Avenue, the material collected from the exterior window ledge of Apartment 1 ID contained 2.25% chrysotile by weight, and the material collected from the top of a wall in the ground-level courtyard contained 2.05% chrysotile by weight. In both samples, these results include large fiber bundles equivalent to approximately 0.2% chrysotile by weight, which were hand-picked from the sediment. No actinoliteZrichterite asbestos was detected in either of these samples. Both of these samples, however, contained low concentrations of amosite. After heavy liquid separation, it was possible to hand-pick fibers of amosite from the centrifugate. During point counting of filters to determine the presence of chrysotile in these two samples, amphibole asbestos fibers were observed. Because all of the amphibole asbestos hand-picked from these samples was amosite, it is reasonable to conclude that the fibers on the corresponding point counting filters are also primarily amosite. Based on this assumption, the concentration of amosite in the sample collected from the exterior window ledge of Apartment 1 ID was approximately 0.016% by weight, and the concentration of amosite in the sample collected from the top of the wall in the ground level courtyard was approximately 0.019% by weight. During the analyses, it was observed that the samples collected north of the World Trade Center site, from the automobile on Church Street and the roof outside the Sth Floor loft at 45 Warren Street, contained substantial amounts of vermiculite. The samples collected from 250 South End Avenue contained substantially less vermiculite, but a higher concentration of chrysotile. Analyses of these four exterior dust and debris samples show that the dust cloud generated by the collapse of the buildings was not homogeneous, and that the dispersed material is different in the two directions from the site. This result would not be surprising if different products had been used in different buildings. Nevertheless, the two samples collected in each of the two differient directions relative to the World Trade Center site are very consistent with each other with respect to both the nature of the constituents and the concentrations of chrysotile and amphibole asbestos. The measurements indicate that

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CITY_21MC100_006730127

NYC-WTC_000199857