NYC-WTC_000232959

NYC 9/11 Public Portal Document

buildings in lower Manhattan were sampled, and four comparison buildings were sampled from the area north of 59th Street. In the 30 lower Manhattan buildings, the following locations were sampled: 59 residential units, 29 common areas, and 29 outdoor areas.

There were 127 air samples taken from 117 different areas of the lower Manhattan buildings. Ten of the areas had co-located sampling equipment. In the 59 different residential units, there were 64 air samples taken. Thirty air samples were taken from 29 different common areas.

Samples taken from the four comparison buildings above 59th Street included three outside air samples, three of common areas with both indoor settled surface dust and air, and five residential units with both indoor settled surface dust and air. No outside settled surface dust samples were collected because there was no visible dust to collect.

Tables 3, 4, and 5 show the number of buildings and areas within the buildings that were sampled for asbestos, SVF, and minerals in lower Manhattan and the comparison units above 59th Street. The tables also show whether the samples were settled surface dust and air samples.

C. Field and Laboratory Changes From the Original Sampling Protocol

Once the sampling teams went to the various sampling locations, it was determined that some changes needed to be made to the sampling protocol. The sections below indicate the changes that were made to the original sampling protocol.

1. Field Changes

The sampling protocol indicated that a total of 60 residential units would be tested in lower Manhattan. A total of 59 residential units were sampled.

Indoor settled surface dust was collected using EPA’s Environmental Response Team Standard Operating Procedure (ERT SOP) for household dust, as stated in the sampling protocol. However, due to cost and equipment availability constraints. Omega Ultivac vacuums with high efficiency particulate air (HEPA) filters were used instead of Nilfisk™ vacuums. To avoid the need to decontaminate the vacuum hose between each sampling event, a sample collection filter (Alsock, by Midwest Filtration) was inserted into the air­ intake end of the vacuum hose. The Alsock has a 97% capture of particles with diameters of 1.1 microns and larger. The ERT SOP-specified vacuum bag filter has a 4- to 5-micron pore size.

Instead of one settled surface dust sample per unit, two co-located indoor settled surface samples were collected. This change was made as two different laboratory locations were involved in the analysis. The EMSL Analytical laboratory in New York City analyzed samples for fibers (using PCM, PLM, and TEM); the EMSL Analytical laboratory in Westmont, New Jersey, analyzed samples for the remaining materials and conducted the SEM analysis for fibers.

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