Final Report Volume 1, WTC Unoccupied Building Monitoring, 125 Cedar

NYC 9/11 Public Portal Document

Final Report 125 Cedar Street, NYC,NY

Ant MONITORING •

Sample Collection

Asbestos and Fibrous Glass ATC collected asbestos and fibrous glass samples of air on 25 millimeter, mixed- cellulose ester filter membranes (0.45 & 0.8 micron pores respectively) contained in manufacturer pre-assembled, three-piece cassettes with electrically conductive, extended cowls. Pump flow rates were determined (both at the start and at the end of the sampling period and periodically by a representative of the NYCDEP) with a secondary standard (rotameter) that is calibrated quarterly against a primary standard (Gilian Instrument Corporation primary flow calibrator "Gilibrator"). Fibers from ambient air were collected with the filter cassette open-faced and positioned between three to five feet above the floor.

Silica In order to collect the desired Silica air samples for analysis, ATC performed the following tasks for air collection. A desired filter and support pad was placed into a three-piece cassette and inserted into the cyclone, which pressed firmly into the center ring of the cassette.

ATC calibrated the pump with the cyclone-cassette assembly in-line using a primary •

standard calibrator. The pumps, complete with cyclone-cassette assembly, were set in the breathing zone. The pump remained in their set positions for the entire sampling period. At the end of the sampling period, the cyclone/cassette assembly was removed from the holder. The cyclone was then removed from the cassette and transported to the lab for analysis.

Air Sample Analysis

Fibrous Glass PCM fibrous glass clearance samples were analyzed by ATC's New York City laboratory utilizing the PCM method of analysis. The microscope used for sample analysis was equipped with a phase contrast condenser. Sizing and fiber counts were performed at 400X magnification. Samples were analyzed by the National Institute of Occupation Safety and Health (NIOSH) Method 7400 using method "B" counting rules. Method "B" rules counts only the ends of fibers that have a length-to-width ratio greater than five-to- one. All air sample results are reported in fibers per cubic centimeter of air (f/cc).

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ATC Project No. 15.22906.0002 Page 5

NYC-WTC 000129382