NYC-WTC_000232959

NYC 9/11 Public Portal Document

to assess high levels of activity, such as cleaning, which might generate short-term periods of higher levels of materials in the air. However, about 40% of the residences were aggressively sampled, which gives some indication of the impact of increased activity on airborne levels.

Although semi quantitative, the minerals detected in air provide important information. Quartz and mica, which have potential health effects on the lung, were found in the respirable fraction of the dust (PM4). This indicates that some portion of the quartz and mica found in the settled surface dust is of respirable size. Minerals found in the larger size air fractions, thoracic (PM 10) and inhalable (PM 100), indicate that larger particles may also be present that could irritate the upper areas of the respiratory tract. It should be noted that these larger fractions also include thoracic and respirable material.

The fiber analysis by PCM provides an upper bound of airborne fibers. Although fiber type is not identified in this analysis, there can be no more asbestos fibers than total fibers detected. Re-analysis of some of these samples shows that very few fibers of public health interest (SVF or asbestos) were present. However, care must be taken when interpreting these results because there were samples taken which showed fibers by PCM, which were not re-analyzed. Any of these air samples, especially those taken in areas with asbestos or SVF in the dust, may have some of these fibers as part of the PCM fiber count. Generally, the levels of dust and air did not indicate a consistent pattern at different locations. It was not possible to conduct a more accurate correlation analysis between asbestos and SVF material in settled surface dust and fibers in air because the majority of air samples were not analyzed specifically for asbestos or SVF (i.e., TEM or SEM analysis). The limited data gathered during this investigation does not support nor refute the assumption that all the fibers in the air samples will be asbestos or SVF even when asbestos was found in dust.

B. Public Health Evaluation

The potential for health effects is possible after exposures to certain materials. An exposure to a material occurs when it comes into contact with or is taken into our bodies. The route of exposure is the method by which a material comes into contact with the body (e.g., dermal contact, inhalation, or ingestion). The nature of the health effect will depend on the material involved, how it comes into contact with the body, the amount of material (exposure level), the duration of the exposure, resultant dose, and the susceptibility of the individual (e.g., pre-existing health conditions may make an individual more sensitive to a contaminant).

Initially, screening values were established and listed in the project-sampling plan. These screening values were established to provide a guideline for evaluating the data as it was collected for any indication of a hazard requiring immediate attention, and to ensure the proper analytical detection limit to support a chronic health evaluation. These screening values were not used in this report because this public health evaluation is specific to the levels of materials found in the study area.

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