NYC-WTC_000232959

NYC 9/11 Public Portal Document

3. Occurrence of Crystalline Minerals

Indoor areas that have elevated levels of quartz in settled surface dust appear to also have elevated levels of calcite, portlandite, and gypsum (see Figure 10). Additionally, these four minerals appear together in all outdoor samples with only minor exceptions. Although only 14 of the 30 buildings had samples taken of outdoor dust, there does seem to be a correlation between elevated outdoor and indoor levels of quartz, gypsum, and the other minerals. It is unknown if this would be seen in outdoor areas above 59th Street for comparison, as not enough outdoor dust was available for analysis.

Most elevated quartz and gypsum levels indoors were found in the first ten buildings sampled during the first 5 days of the project (with the exception of 14% quartz in the common area of building 22). Although many of these buildings were closer to the WTC site, location may not be the only factor contributing to higher mineral levels in the dust. Other buildings sampled in these areas later (e.g., 13, 14, and 28) did not have elevated levels of minerals. Many factors may contribute to this finding including whether the area was cleaned (indoors, outdoors), the cleaning method used, the time since the last cleaning, and the amount of dust that was initially in the area. It is not clear which factors contributed to variation in mineral levels by building.

Within a building, levels of quartz, calcite, and portlandite tended to be similar, and in some cases showed a similar profile in areas with elevated quartz (see Figures 13, 15, and 16). In general, where quartz was greater than 5%, calcite and portlandite were also present, but as smaller proportions of the dust. Gypsum, although often present with the other minerals, varied from being the most abundant to the least abundant in the dust.

4. Buildings Impacted by Asbestos, Synthetic Vitreous Fibers, and Crystalline Minerals

There was no clear pattern of which buildings were impacted by asbestos, SVF, and crystalline minerals. Figure 17 shows the approximate locations of the buildings and the level of contaminants in settled surface dust that were above or below the levels found in the comparison areas. The data are summarized and presented to indicate the indoor areas within a building with higher levels of a material in settled surface dust than was found in the comparison areas above 59th Street (Table 12). In this table, quartz was considered representative of the two other minerals associated with concrete, portlandite and calcite.

In 6 of the 29 buildings (approximately 21%) sampled in lower Manhattan, concentrations of these materials were not detected at levels higher than the levels in the comparison buildings above 59th Street. These six buildings tend to be among the buildings farthest from the World Trade Center and not located along what appear to be major streets or intersections. Map 17 shows the approximate locations of the buildings and the level of contaminants in settled surface dust that were above or below the levels found in the comparison areas.

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