NYC-WTC_000232959

NYC 9/11 Public Portal Document

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 the comparison 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 crystal I i ne 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 aU 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 laboratory is part of EPA’s “certified” Contract Laboratory Program. It used all of the EPA quality assurance/quality control laboratory methodologies when analyzing the samples collected for this investigation. EPA conducts audits of all the EPA-certified laboratories to assure that appropriate quality assurance/quality control laboratory methodologies are being used.

Chain-of-custody procedures were established and maintained throughout sample collection, transportation, and analysis of samples. These procedures helped to assure that analytical results could be matched to the sampling locations.

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NYC-WTC_000232983