VOC sampling locations table for Ground Zero area, Jan 2002

NYC 9/11 Public Portal Document

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Lioy et al. (2002) provides complete descriptions of numerous other specific compounds that were found in dust particles that settled outdoors. They also noted that penetration of substantial quantities of WTC-derived dust into indoor office or residential spaces likely notably increased the potential for indoor exposures (via ingestion or by inhalation of re-entrained particles) to high levels of constituent elements and compounds.

More detailed chemical analyses have been performed on aerodynamically size-separated PM2.5 derived from bulk dust samples collected on September 12 and 13 from several locations withing 0.5 miles of Ground Zero (EPA, 2002c; McGee et al., 2002). These analyses showed that calcium sulfate (gypsum) and calcium carbonate (calcite) were major components of the fine fraction, indicating that very finely crushed building materials were still dominant components even in this size range. Fine particles more easily penetrate into offices and residential spaces and thereby contribute to indoor exposures more readily than coarse particles.

Data for EPA/ORD measurements of PM elemental composition of fine particles (PM2 5) for samples collected starting September 21 are graphically depicted in Figures 14 to 18. The elements are grouped in each figure roughly according to their relative abundance in the subject air samples, those in Figures 14 to 16 being among the most abundant and those in Figures 17 to 18 being distinctly less abundant. Most of the elements shown in the figures were well correlated (r > 0.85) with each other at individual sites, with several being much more highly correlated (r > 0.95) with each other and with PM2 5 throughout the sampling campaign. The very high correlations suggest a common source origin for these elements, that is, WTC fires. The composition of the emissions from Ground Zero combustion sources changed with time as evidenced by initial peaks in several elements (e.g., calcium, potassium, sulfur, chlorine, bromine, lead, copper, and zinc) dining late September and early October (Figures 14 to 16), followed by later peaks in the concentration of chromium, arsenic and antimony during mid- or late November (Figures 17 and 18). The elements for which data are depicted in Figures 14 to 18 were selected for illustration from a larger set measured by ORD, based on evident elevations of their concentrations over typical background levels at some point during the sampling campaign.

Consistent with Lioy et al.’s finding of highly enriched calcium in both fine and coarse fractions of settled dust near the WTC, markedly increased levels of calcium continued to be seen in airborne fine particles (Figure 14) at ORD’s Ground Zero perimeter sites off and on throughout September and October and much of November, decreasing to low background levels by late November. Elevated levels of calcium in the fine fraction are indicative of highly pulverized building materials (e.g., wallboard) from the WTC site. However, except for a few occasions (e.g., on October 6), airborne fine PM calcium levels were not markedly elevated above background levels at the EPA 290 Broadway site a few blocks northeast of Ground Zero, whereas calcium in the PM,0,2.5 coarse fraction (not graphically depicted here) did show rather frequent elevations at the 290 Broadway site but decreased to low background levels by the end ofNovember.

Fine PM silicon elevations were only evident briefly during October 3-5 at Location A

DRAFT-DO NOT QUOTE OR CITE 33 October 2002

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