WTC environmental investigation report, Sep 2002

NYC 9/11 Public Portal Document

Final Technical Report of the Public Health Investigation Page 19 of 56 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.

Delays in obtaining equipment resulted in only 10 buildings being sampled for the PM2.5 air fraction.

There was no visible settled surface dust around the comparison homes selected above 59th Street; therefore, no outdoor settled surface dust samples were collected from thecomparison areas above 59th Street.

2. Sample Analysis Changes

Airborne and settled surface dust samples were analyzed for crystalline silica using EMSL Analytical's Material Science Division Operating Procedure MSD 0700, January 2000. XRD analysis was conducted for the nonsilica crystalline minerals in air and settled surface dust samples by EMSL using Material Science Division Operating Procedure MSD 9300, January 2002. The samples were not ashed prior to XRD analysis for the following reasons: ashing samples could have resulted in loss or breakdown of analytes of interest including gypsum; and there was not enough organic material present to result in loss of method sensitivity for crystalline minerals of interest.

SEM analysis was conducted on air samples for fibrous glass and other synthetic vitreous fibers by EMSL using Material Science Division Operating Procedure MSD 0300. This analysis was conducted on all samples collected from the comparison areas above 59th Street and on only those air samples from lower Manhattan with PCM fiber concentrations higher than the comparison PCM fiber concentrations.

Settled surface dust samples were analyzed for fibrous glass by EMSL using New York State Department of Health Environmental Laboratory Approval Program Method 198.1 polarized-light microscopy methods for identifying and quantifying asbestos in bulk samples.

Settled surface dust samples were not weighed, so surface loading of materials could not be calculated. Although settled surface dust samples were sieved, sieving was not conducted as specified in the ERT SOP. Rather, sieving was conducted as specified in MSD 0700 and 9300.

D. Data Management and Quality Assurance/Quality Control Procedures

EPA provided the laboratory used for this investigation. The http ://www.atsdr.cdc.gov/asbestos/lowermanhattan/ResSamp_Sep2002_Text.html 07/18/2003 NYC-WTC_000178406