VOC sampling locations table for Ground Zero area, Jan 2002

NYC 9/11 Public Portal Document

network, concentrations of PMj j and a number of key elements were measured from February to June, 2000, in NYC (at the Bronx Botanical Gardens), Boston, and Philadelphia, at sites that were likely characteristic of urban backgrounds. As shown in Table 2, the average concentrations of PM2 5 and the individual elements measured at the three sites varied relatively little in contrast to those measured near the WTC site. The highest measurements of PM2 5 and heavy metals are also shown in Table 2 for comparison. During the first weeks after September 11, PM2 5 levels and concentrations of several elements often were many times higher than those obtained at the northeastern sites listed in Table 2. As also seen in Table 2, concentrations recorded at the New York University Medical Center in 1976 (Bernstein and Rahn, 1979) were higher than those at the other Northeastern sites, but they were still distinctly lower than the measurements made soon after September 11.

During December and January, the concentrations of most of the elements measured by ORD decreased to levels similar to those measured at the northeastern sites, suggesting that the WTC was no longer a significant source of these elements. However, it should be noted that even the markedly elevated element concentrations over typical background values noted mainly in September and October did not exceed applicable OSHA PEL (8-hour time-weighted average) values or other more broadly applicable health benchmark values, suggesting a generally low health risk for those working at Ground Zero or others present in lower Manhattan neighborhoods around the WTC.

Alkalinity of the dust from the WTC disaster may have been a possible health concern for exposed individuals. Some reported symptoms (eye, nose, and throat irritation; nose bleeds; cough) may have been due to exposure to unusually elevated quantities of certain crustal materials derived from pulverized concrete, wallboard, and other WTC structural components present in airborne particles and settled dust in neighborhoods near the WTC. The United States Geological Survey (USGS, 2002). Lioy et al. (2002), and McGee et al. (2002) all reported testing aqueous solutions of WTC settled dust and finding an initially high alkalinity (generally pH 10.0), which decreased to pH 8-9 for outdoor samples taken after rainfall (as reported by USGS). Because much of the outdoor settled dust was removed by hazardous material cleanup procedures or was washed away by rainfall during late September, outdoor exposures to highly basic PM components would seem to be of much less potential health concern beyond late September when restricted zone shrinkages allowed more people and traffic in neighborhoods immediately surrounding the WTC work zone. However, USGS noted higher alkalinity for dusts sampled indoors, raising the possibility of greater risk of acute irritation symptoms being associated with indoor exposures to WTC dusts than with outdoor dusts leached by rainfall.

Lioy et al. (2002) more broadly highlighted indoor exposures to WTC-derived dust PM as posing potential increased health risks. Individuals visiting, residing, or working in buildings not adequately cleaned before reoccupation could have been subjected to repeated, long-duration exposure to many of the components from the original WTC collapse found by Lioy et al. in settled dust to the east of the WTC. Lioy et al. noted that long, narrow glass fibers in the WTC-derived dust had various potentially toxic materials attached to them and could contribute to acute short-term irritative effects and possibly to more chronic health risks.

Also of potential concern would be any extended indoor air exposures to finely pulverized

DKAFT-DO NOT QUOTE OR CITE 40 October 2002

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