VOC sampling locations table for Ground Zero area, Jan 2002

NYC 9/11 Public Portal Document

antimony in mid-November at ORD Site K on the southwest perimeter of Ground Zero (but not at Sites A or C or at 290 Broadway to the north, northeast, or southeast of the WTC) suggests both a different source of WTC fire emissions and a likely climatic shift to winds flowing mainly from the north/northeast to the south/southwest. The chromium elevations seen around November 20, mainly at Site C, suggest possibly yet another later shift in the composition of Ground Zero sources of WTC-generated airborne particle emissions. Hence, the “WTC signature” appears to have varied over time in terms of its specific elemental composition.

In contrast to the above patterns of element levels which indicate that they may have originated fi-om the WTC fires, the gradually increasing concentrations of nickel up to a range sustained during December and January (after the WTC fires were out) seem to argue against any notable airborne fine-particle nickel emissions from the WTC fires subsequent to the collapse of the WTC buildings on September 11. Still, enrichments in samples of settled dust fi’om sites east of the WTC (Lioy et al., 2002) are likely indicative of nickel having been among the metals present in high concentrations of airborne particles in the initial dust/smoke that enveloped lower Manhattan on September 11. This raises the possibility of (a) any remaining nickel-containing dust being re-entrained into outdoor air during later rescue/recovery operations and/or (b) continued elevations of nickel concentrations in WTC-derived indoor dust and re-entrained indoor air particles.

3. High Temporal Resolution Analyses The ORD PM2 5 and associated element measurements discussed above were obtained over sampling periods of close to 24 hours. Examination of additional data is necessary to determine more precisely the duration and nature of enhanced concentrations of PM constituents and to help understand possible public health impacts of such excursions. For example, of much interest are PM elemental composition data for the period October 3-5, when a high pressure system settled over New York during the early morning hours of October 3 and 4. Concentrations of sulfur were close to six times higher at the downwind ORD WTC site (Site A) than at the upwind site (Site K) on October 4. Concentrations of a number of other elements were also much higher by large enrichment factors at Site A as compared to Site K, as indicated by the enrichment factors (noted in parentheses) for the following elements: silicon (4IX), chlorine (500X), potassium (47X), calcium (5X), bromine (350X), copper (130X), zinc (1 lOX), palladium (> lOOX), cadmium (>100X), antimony (>100X), and lead (66X). Overall, the above results are most consistent with brief, episodic increases from WTC Ground Zero during early morning hours on October 3 and 4 leading to elevated concentrations of PM and its constituent elements at WTC perimeter sites and one or another sites in lower Manhattan located downwind of the WTC on those days (i.e., to the north and/or northeast). These enhanced concentrations were superimposed on generally higher concentrations of PM and its constituents found upwind of the WTC on those days. The higher concentrations found at the upwind sites were associated with a high pressure system that settled over the New York Metropolitan Area during that period. In any case, the results suggest strongly that the WTC site was the dominant source of these elements on October 3-4.

University of California, Davis measurements (Cahill et al., 2002) on the roof of the DOE building indicate a sharp increase in concentrations of PM2 5, mainly in the size range between 0.34 to 0.56 pm on the morning of October 3, as shown in Figure 19. This very brief excursion

DRAFT-DO NOT QUOTE OR CITE 35 October 2002

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