NYC-WTC_000208359

NYC 9/11 Public Portal Document

Crystalline Minerals in Settled Dust

Table lb shows the estimated percentages of minerals in settled dust samples that were collected inside your building and when possible in the near vicinity outside of your building. Generally, levels in and around lower Manhattan residences were higher than comparison locations. These findings point to the continued need for frequent cleaning with HEPA vacuums and damp cloths/mops to reduce the potential for exposure.

Table lb Crystalline Minerals in Settled Dust for 31 N Moore Street and the upper Manhattan Comparison Area (percent of mineral in sample)

__________ 31 N Moore Street*__________ Comparison Area* Minerals in Common Outdoor Residence Residence Common Outdoor Residences Settled Area Area Dust Quartz ND NS 0.05 0.9 1 NS 2 Cristobalite ND NS ND ND ND NS ND Tridymite ND NS ND ND ND NS ND Calcite ND NS ND 0.6 0.4 NS 0.9 Portlandite ND NS ND 0.09 0.05 NS 0.08 Gypsum 0.07 NS 1 1 3 NS 4 Mica ND NS ND ND ND NS 0.08 Halite 0.04 NS ND 0.05 ND NS 0.4 *Results are maximum values found in location NS = not sampled ND = not detected

Fibers: Asbestos and Synthetic Vitreous Fibers

Potential Health Effects

Exposure to airborne asbestos is known to increase lung cancer and other diseases mostly among occupational groups in the construction, shipyard, and some manufacturing industries. Risk for disease increases as the level of asbestos exposure and the length of time of exposure increase. Although low level, brief exposures to asbestos are very unlikely to result in disease, it is advisable to avoid any exposure. Synthetic vitreous fibers, such as fiberglass, are manmade materials. The primary short-term health effects of exposure to synthetic vitreous fibers (SVF) are skin, upper respiratory tract and eye irritation. Textile and cellulose fibers were also detected in some of the samples. These fibers can also be irritants at very high levels.

Fibers in Air

Table 2a describes the results of air sampling for fibers at your building. Phase contrast microscopy (PCM) is used to identify fibers based on size and shape. This technique cannot identify the specific type of fiber. Therefore, the fibers seen by PCM include asbestos fibers as well as other fibers, such as textiles, fiberglass, and cellulose, which might be present. If the results v/ere above the comparison background level using the PCM methodology, additional analysis was performed to determine whether any of the fibers were asbestos (TEM methodology) or synthetic vitreous fibers (SEM methodology).

CITY_21MC100_010212192

NYC-WTC_000208361