Environmental assessment report, 100 Church Street, April 2002

NYC 9/11 Public Portal Document

Using TEM, asbestos fibers, bundles, clusters or matrices are counted as structures. A structure is considered part of this group (i.e., a countable fiber) based on geometric and dimensional criteria. That is, a structure must satisfy size requirements (greater than 0.5 micrometers long) and have an aspect (length to width) ratio of greater than 5 to 1. All structures fitting these criteria are counted. The method allows the analyst to distinguish between asbestos and non-asbestos structures.

The airborne structure concentration is calculated by proportioning the structures counted per area of filter to the total filter area. The result is an expression of the concentration of airborne asbestos in structures per square millimeter (s/mm ).

4.5.2 Metals Sampling and Results Thirty-five (35) air samples, including blanks, were collected and analyzed for twenty-two (22) metals. Results of metals air samples are presented in Table 11 of Appendix A. A review of the results indicate that most of the air samples were found to be below the analytical detection limit for metals. Only two (2) air samples were found to contain measurable concentrations of metals in the air and for those samples, only lead was detected in one and aluminum was detected in the other. For those two samples in which measurable concentrations of specific metals were identified, all air concentrations were much lower than their respective OSHA permissible exposure limits (PELs).

4.5.3 Volatile Organic Compounds Sampling and Results Eight (8) air samples were collected and analyzed for twenty-three (23) volatile organic compounds (VOCs). Results of VOC air samples are presented in Table 12 of Appendix A. While measurable concentrations of specific VOCs were identified in some of the air samples, all air concentrations were much lower than their respective OSHA PELs.

4.5.4 PAHs Eight (8) air samples were collected and analyzed for semi-volatile organic compounds polynuclear aromatic hydrocarbons (PAHs) (16 individual semi-volatile compounds). Results of PAH air samples are presented in Table 13 of Appendix A. A review of the data indicates that all of the results were below the analytical detection limit for PAH compounds.

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