NYC-WTC_000199812

NYC 9/11 Public Portal Document

5.0 ASBESTOS MEASUREMENTS

5.1 Asbestos in Passive Air Samples

5.1.1 Sample Collection

Air samples were collected using 25-mm-diameter 3-piece plastic cassettes with short cowls. Each cassette contained a 25-mm-diameter, 0.45-pm porosity, mixed esters of cellulose (MCE) filter, with a 5.0-gm MCE back-up filter and a cellulose support pad. Each sampler operated at a flow rate of approximately 9 liters/minute and was calibrated at the start and finish of sampling. All air sampling was conducted under passive conditions, and no air conditioning or ventilation systems were operating at the time of sampling. Considerable amounts of settled dust and debris were present on all horizontal surfaces in each of the apartments where the indoor samples were collected. Disturbance of this surface dust was minimized, personnel were near the air samplers only to monitor their operation, and dust and debris samples were collected with a minimum of disturbance. At 45 Warren Street, three air samplers were positioned in the 2nd Floor apartment and three in the 5th Floor apartment. An exterior sample was also collected on the roof outside the 5th Floor loft. Each of these samplers operated over a period of time sufficient to collect the particulate material from approximately 1200 liters of air. An open field blank and a closed field blank were included with this set of air samples. At 250 South End Avenue, five samples were collected in Apartment lOD, and one exterior sample was collected by positioning the cassette outside a sliding window. An open field blank and a closed field blank were included with this set of air samples. The intent was to collect particulate material from approximately 1200 liters of air, but the sample collection had to be terminated prematurely because the filters were becoming overloaded.

5.1.2 Analysis f

The sample filters from 45 Warren Street were prepared and analyzed by tnMwrairiiiioti» elecUoft aaerostxjpy (TBM) using the direct-transfer method ISO10312. An initial attempt to prepare TEM specimens by ISO 10312 from the air sample filters from 250 South End Avenue

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NYC-WTC_000199833