NYC-WTC_000232959

NYC 9/11 Public Portal Document

ABSTRACT

The New York City Department of Health and Mental Hygiene and the U.S. Agency for Toxic Substances and Disease Registry in collaboration with the U.S. Public Health Service Commissioned Corps Readiness Force and the World Trade Center Envhonmental Assessment Working Group conducted a limited investigation of residential areas near and around the World Trade Center (WTC). The purpose of the investigation was to assess potential exposures to airborne and settled surface dust that entered residential areas following the collapse of the WTC buildings.

Sampling of the residential areas occurred from November 4 through December 11, 2001, and was conducted by U.S. Public Health Service Commissioned officers detailed to the New York City Department of Health and Mental Hygiene with assistance from the New York City Department of Health and Mental Hygiene.

The results of this investigation do not necessarily reflect levels that would be found in other lower Manhattan buildings or residential areas; the measurements reflect levels that were present at the time of sampling in the specific residential areas sampled. The limited number of results obtained from the comparison areas above 59th Street may or may not reflect the New York City-specific background levels of asbestos, synthetic vitreous fibers (SVF), mineral components of concrete (quartz, calcite, and portlandite), and mineral components of building wallboard (gypsum, mica, and halite).

Low levels of asbestos were found in some indoor and outdoor settled surface dust, primarily below Chambers Street. Many of the lower Manhattan locations sampled had been cleaned prior to this investigation. No asbestos was detected in the comparison indoor dust samples taken north of 59th Street. Not enough visible settled dust was available to collect outdoor samples in the comparison area. When compared with the results obtained from the sampling locations above 59 Street, the lower Manhattan residential area settled surface dust sampling results tended to have higher percentages of SVF, mineral components of concrete (quartz, calcite, and portlandite), and mineral components of building wallboard (gypsum, mica, and halite) in settled surface dust.

Because asbestos, SVF, mineral components of concrete (quartz, calcite, and portlandite), and mineral components of building wallboard (gypsum, mica, and halite) were found at higher levels in settled surface dust in lower Manhattan residential areas when compared to comparison residential areas above 59th Street, the New York City Department of Health and Mental Hygiene and the U.S. Agency for Toxic Substances and Disease Registry are recommending that people continue to conduct frequent cleaning with HEPA vacuums and damp cloths/mops to reduce the potential for exposure and/or participate in the U.S. Environmental Protection Agency cleaning/sampling program.

Total fiber counts of air samples taken in lower Manhattan were similar to the comparison areas above 59th Street sampled during this investigation. The six lower Manhattan areas that had elevated total fiber counts were re-examined by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The TEM and SEM results indicated that

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