NYC-WTC_000232959

NYC 9/11 Public Portal Document

The sampling team completed building surveys, in part, to gather the information needed to cite sample locations and to provide information to be used in interpreting the results. These surveys were completed on the basis of their observations and on discussions with building management when representatives were available. However, information was not always available to completely answer each survey question. This was especially true when evaluating specifics of the heating and air conditioning systems. The validity of the information is dependent on the memory and experience of the building representatives and, in the case of residential units, may not reflect the condition or treatment of the entire building.

The survey form and photographs were reviewed along with the analytical results to put the sampling results into the context of where and how the samples were obtained and to determine the general conditions of the sampling locations. Given the purpose of this investigation, the limited amount of locations sampled, and the uncertainty in some of the survey results, no attempt was made to correlate survey information with measured concentrations of any of the materials. The table in Appendix B provides a summary of results from the survey form questions that were most consistently answered.

B, Settled Surface Dust

Settled surface dust samples were analyzed for materials consistent with debris from a building collapse. Materials of interest include insulation material (asbestos, synthetic vitreous fibers, components of concrete (portlandite, calcite, and crystalline silica) and components of other building materials (gypsum, mica, and halite). A detailed summary of results is given in Appendix C. To protect the privacy of individuals who allowed sampling in their residences and buildings, specific detailed locations are not shown. Results of the settled surface dust analysis indicate the composition of settled surface dust in lower Manhattan is different from that of the dust analyzed from the comparison areas above 59th Street. Although the materials found are consistent with materials expected from the World Trade Center collapse, these results cannot determine the actual source of the materials present because these materials are common building components and can come from other sources in a busy urban area.

1. Fiber Analysis of Settled Surface Dust

All settled surface dust samples were Asbestos and SVF, although not analyzed by polarized light microscopy found in homes in the comparison (PLM) for fiber type and content. This areas above 59th Street, were technique distinguishes between asbestos fibers, textile fibers, and synthetic vitreous present in the settled surface dust fibers (SVF), which include glass wool and in some areas of lower mineral wool. The results are reported as a Manhattan. percent. Because PLM is an optical method, the amount reported is a visual estimation of the percent of area viewed. Therefore it is neither strictly a weight or a volume percent.

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