WTC environmental investigation report, Sep 2002

NYC 9/11 Public Portal Document

Final Technical Report of the Public Health Investigation Page 28 of 56 0.003 f/cc). Six of these air samples (from 3 common areas and 3 residences) had higher levels of fibers in air than the comparison areas above 59th Street (Table 8). Four of these areas had measurable levels of SVF in the settled surface dust. All six-air samples were re-analyzed by TEM to determine if the fibers present included asbestos fibers. Asbestos fibers were not found in these six air samples (Table 8). A third analysis was done by SEM to determine if SVF fibers were present in those air samples from areas with SVF in the settled surface dust. SVF fibers were found in three of these air samples at concentrations from 0.000037 f/cc to 0.000255 f/cc. Although SEM is a more sensitive method, detecting thinner fibers than PCM, reported SVF levels were well below the PCM method detection limit of O.OOlf/cc. SVF fiber concentrations in the comparison areas above 59th Street ranged from none detected to 0.000087 f/cc. Although air samples from comparison areas above 59th Street were not re­ analyzed by TEM, no asbestos fibers were noted on the subsequent SEM analysis for SVF. Therefore the six air samples that had total fiber counts greater than comparison areas above 59th Street were not elevated due to either asbestos or SVF fibers.

There were 15 out of the 83 (18%) indoor areas in lower Manhattan with measurable asbestos in the settled surface dust, 10 residences and 5 common areas (Table 9). Nine of these residences were sampled aggressively (the air exhaust of the vacuum used for settled dust sampling was used to stir up all dust into the air before an air sample was taken). Four of these aggressively sampled residences had measurable fiber levels in air ranging from 0.001 f/cc to 0.003 f/cc. One residence was occupied and could not be aggressively sampled. Air sampling at that location indicated <0.001 f/cc by PCM analysis. Because the levels found were within the range measured in the comparison areas above 59th Street, no TEM or SEM re-analysis was performed on these air samples. Therefore the composition of these fibers is unknown (i.e., asbestos, SVF, cellulose).

None of the common areas were aggressively sampled because all of these areas were open to the public. Of the five common areas with some asbestos in the dust, three had measurable levels of fiber in the air ranging from 0.001 f/cc to 0.002 f/cc. One area in building 5 where there was not enough settled surface dust to sample had an airborne fiber count of 0.002 f/cc. No TEM or SEM re-analysis was performed on these air samples, and the composition of these fibers is unknown (i.e., asbestos, SVF, cellulose).

b. Outdoor Air

Six of the 14 lower Manhattan outdoor locations sampled had detectable levels of asbestos in the settled surface dust, indicating a potential in these locations for asbestos fibers to become airborne. Air sampling indicates three of the locations did not have detectable fibers in the air (Table 9). The air samples from buildings 1, 2, and 5 did have fibers detected at levels from 0.001 f/cc to 0.003 f/cc. Of the 15 locations where no settled surface dust samples were taken, the majority of the results showed <0.001 f/cc in the air, with only 4 samples reported at the

http://www.atsdr.cdc.gOv/asbestos/lowermanhattan/ResSainp_Sep2002_Text.htnil 07/18/2003 NYC-WTC_000178415