NYC-WTC_000232959

NYC 9/11 Public Portal Document

Table 8 Summary of Results for Locations With Airborne Fiber Levels Higher Than Levels in Comparison Areas Above 59th Street

Air samples were collected and analyzed by phase contrast microscopy for total fibers (NIOSH 7400). All samples with fiber counts higher than the comparison areas above 59th Street were re-analyzed to determine if those fibers were asbestos, synthetic vitreous fibers (SVF), or other material.

Building Aggressive Fibers in Air by Asbestos in Asbestos in Air SVF in Dust SVF in Air by (Area) Sampling" PCM Dust by PLM by TEM by PLM SEM (f/cc)*’ orTEM® (f/cc)*’ (f/cc)*’ 1 (Residence) No 0.006 ND“ <0.00? 20% 0.000162

(Common) No 0.005 ND“ <0.001'* 27% 0.000255 19 (Common) No Overloaded" ND® <0.006^ ND Not analyzed 24 (Residence) No 0.005 ND® <0.001'* 10% 0.000037 26 (Common) No 0.004 ND® <0.001'* 5% <0.00004 26 (Residence) No 0.012 ND® <0.001'* ND <0.00004 a. Aggressive sampling refers to a technique used in some residential units where the vacuum exhaust (used for settled dust sample collection) was used to stir up the settled surface dust before the air sampling began. b. f/cc = fibers in each cubic centimeter (cc) of air as determined using phase contrast microscopy (PCM), transmission election microscopy (TEM), or scanning elechon microscopy (SEM) mediods. This is calculated from the number of fibers seen on the air filter and the volume of air pulled through the filter measured in cubic centimeters of air. c. Value shown represents the highest of polarized light microscopy (PLM) or TEM results for this area. d. The TEM method employed here, National Institute of Occupational Safety and Health (NIOSH) 7402, counts fibers of the same size as those detected by PCM analysis. Fibers reported here are greater than or equal to 5 microns in length and 0.25 microns in width. e. A building renovation project was occurring near the area of this sampling equipment. Constniction dust and building insulation material may have influenced this sample. f. Sample processing of the overloaded filter involved transferring the material to a new filter; this process provides less analytical sensitivity, resulting in a higher detection limit. g. ND = not detected.

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