80 JOHN STREET; Block: 68 Lot: 33 BIN: 1001115 19-25 Gold Street, 25-27 Platt Street

NYC 9/11 Public Portal Document

110.157 DEC. 3.2001 12:07PM JLC ENVIRONMENTAL

WSA Management JLC Project # 01-2222 December 3, 2001 page 2 is and P

Introduction the filter content of a known volume of air Air sampling is defined as the process of measuring Each sample is cross-referenced by entrained on a fitter membrane over a specified period of time. ensure proper, consistent handling through a chain field designation and a JLC lab internal code to HEPA filter clean bench to avoid any possible. of custody. Sample preparation takes place within an contamination.

Methodology Institute of Occupational Safety and Test procedures for these samples confonjji to the National Health (NIOSH) standards. breathing zone of persons anticipated to . ; Air sampling was conducted at a level approximating the collected should represent the area's be present in the area during normal operations. Samples typical airborne fiber concentration. 0.8 micrometer (pm) cellulose ester +~1' All samples were collected on fully exposed 25 millimeter, membrane air sampling cassettes with conductive cowl. ` ' b"`'

Analytical Procedures percent of the total filter was removed and placed on A section of the filter approximating twen -five approximately 250 microliter (p1) of acetone a pre-cleaned microscope slide and then exposed to clean #1.5 cover slip was placed vapor. A single 3.0 - 3.5 pl drop of triacetin was applied and a heater until clarity allowed analysis to slide upon the fitter. The prepared slide was then heated on a be conducted.

Analysis was accomplished utilizing a Contrast Microscope in accordance with NIOSH 7400 method, counting rule "A." 4.

Contrast Microscopy Contrast Microscope, (PCM) JLC Environmental's laboratory uses an 0 (mpus BH-PC Phase first dissolving the filter equipped with a Walton-Beckett Graticule. Samples were analyzed by the fibers with PCM at 400x t:: .:+ through a chemical process (described ab ve) and then counting object and the background, magnification. Phase contrast increases t e light contrast between the 100 microscopic fields or 100` thus enhancing the microscopist's ability t, see fibers. Normally, , r ;t fibers are counted, whichever occurs first.

Results analysis of the samples. The: The "Summary of Analytical Results" represents the results of the centimeter (f/cc) of air. If final tests PCM limit of reliable quantification is less than 0.01 fibers/cubic -cleaned-and re-tested. do not meet these requirements, the entire work site must be re

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