Preliminary health report, World Trade Center, Oct 2001

NYC 9/11 Public Portal Document rWorldTradeCenter.pdf Page 2

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Submitted to American Industrial Hygiene Association. October 2, 2001

finding no elevated hazardous aerosols or chemical vapors under outdoor conditions. To further investigate potential health hazards posed by site conditions near the WTC disaster site, a study of site conditions north of WTC Building #7 was conducted. This study measured a broad profile of potential hazards in surface residue and work zone air. Data related to asbestos content of surface residue and asbestos aerosols is reported. Data for other potential hazards has been presented separately.'

Reliable estimates of the nature and extent of asbestos-containing building materials installed at the WTC buildings is not available at this time. It is believed that asbestos­ containing, spray-applied fire resistive coating was present on portions of structural steel on the lower floors of tower #1 (north tower) and elevator shaft structural steel, that asbestos-containing decorative finishes were originally applied to building lobbies and other public areas, and that up to 8.5 million square feet of vinyl asbestos floor tile was originally installed in WTC tower #1 and #2.

The energy and resulting force associated with the collapse of WTC tower #1 and #2 are consistent with the visual and tactile examination of the resulting debris and surface residue. For this reason, and to build a reliable foundation for assessing potential health risks associated with work that disturbs this surface residue, a particle characterization of the surface residue was conducted. Data from this characterization was used to design a study of workplace asbestos aerosols that included careful selection and execution of routine analytical methods to produce reliable data characterizing the workplace atmospheres.

Study Design & Methods

The study of surface residue focused on areas surrounding WTC Building #7 to the north (figure 4), east and west for a distance of four city blocks. A total of eleven specimens of surface residue were collected using separate and clean wooden spatulas (figure 3). Each specimen of surface residue was placed in separate 50mL conical plastic containers tightly closed with screw tops. Two specimens, (one from location #6 and one from location #10) were shipped by overnight mail to MVA, Inc. for particle size and compositional characterization. Eleven specimens were shipped by overnight mail to AMA Analytical Services, Inc. (Lanham, MD) for determination of asbestos content by PLM using ERA 400 point count quantitation. Specimen splits were also examined by HP Environmental to determine asbestos content by PLM using visual estimation quantitation.

Locations were selected for collection of surface residues by superimposing over the area of interest a semicircular grid with a diameter of eight city blocks (approximately 2,000 feet). Five radians were extended east, northeast, north, northwest and west from a focal point at the northern base of the WTC Building #7 rubble pile. Specimens of surface residue were collected at two points along each radian, the first at a distance of

’ A complete set of data available from this Preliminary Health Hazard Assessment was presented on September 28, 2001 to the WTC Site Safety Committee and is available from Mr. David Collins, Director of Health and Safety, Turner Construction Company, NY, NY

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