Special Investigative Audit #14 Draft, WTC Site, Nov 2001

NYC 9/11 Public Portal Document

general trends from sites within close proximity. The results, illustrated in Figure 4, show a noticeable decrease in the concentration of f'cc over time at the selected Lower Manhattan locations, and a corresponding increase in the concentration of f/cc over time at the selected Fresh Kills Landfill locations.

Of the 3466 ambient air samples analyzed by PCM, 89%, or 3100, were also analyzed by TEM to determine the concentration of asbestos fibers in S/mm2. One thousand five hundred seventy three (1573) of these samples were collected at Locations A-V in Lower Manhattan. A total of twelve (12) results were reported at concentrations greater than 70 S/mm2 at Locations A, D, E, F & K. At the Fresh Kills Landfill, TEM analysis was performed on 1243 samples, with 17 results reported at concentrations greater than 70 S/mm2. The highest results, ranging from 88 to128 S/mm2, were measured at the Screening Operations (Locations 09-A & 09-B) and Location 12-A between October 8th and October 31St. There were also eight (8) results reported at concentrations greater than 70 S/mm2 at other Manhattan locations. These include results of 105 S/mm2 reported at Site 02 - Manhattan Boro Community College on September 9th, 157 S/mm2 at Spruce and Gold St on September 12t , and 93 S/mm2 at Site 08 - Public School 199 - 3290 48th Avenue on October 1St. To allow for a comparison between total fibers detected by PCM and asbestos fibers detected by TEM, the same locations tabulated and trended for the PCM results were also tabulated and trended for the TEM results. The date collected and reported concentrations, along with the corresponding PM 2.5 results and average wind speed, are shown in Table 5. As with the PCM data, for those dates in which more than one sample was collected and analyzed for a given location, the higher of the reported results is used. As with the PCM data, no trends were observed between reported TEM concentration, and the PM 2.5 and average wind speed data. The highest of the results from the Fresh Kills Landfill locations (09-A, 09-B & 12-A) and Lower Manhattan locations (B, D, E & F) ) were then plotted by date collected (x-axis) and f/cc (y-axis). The results illustrated in Figure 5 show a decrease in the concentration of S/mm2 over time at the selected Lower Manhattan locations, and an increase in the concentration of S/mm2 over time at the selected Fresh Kills Landfill locations.

PAM Samples:

A total of three hundred fifty eight (358) personal air monitoring (PAM) samples were collected from locations in Lower Manhattan and at the Fresh Kills Landfill between September 11th and September 23`d. Three hundred thirty eight (338) or 94% of these samples were collected in Lower Manhattan locations. The Lower Manhattan samples were collected from three zones: the Work Zone, the Perimeter, and Nearby Neighborhoods. The PCM results from these three zones have been plotted by date collected (x-axis) and f/cc (y-axis). The results illustrated in Figure 6 show a decrease in total fiber concentrations from September 12th to September 23`d from all three zones. Twenty (20) PAM samples were collected at Fresh Kills Landfill locations on September 18t'' and 19t'', with results reported between 0.018 f/cc and 0.175 f/cc (see Table 6). Additional TEM analyses were performed on 23 of the PAM samples collected in the Lower Manhattan Zones on September 12th and 15t''. Nine (9) of these samples were reported at concentrations greater than 70 S/mm2 (see Table 7). For both the Fresh Kills Landfill PCM results, and the Lower Manhattan TEM results, too few data points were available to determine possible trends.

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