Document header for 61 Broadway records, 2002

NYC 9/11 Public Portal Document

FROM : FAX NO. : Jan. 0® 2000 10:28PM PE

Deer Real Estate Services, Inc. JLC Project # 01-2129 October 16, 2001 page 2 J1SamDIIn Anal and Procedu

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

Methodology Test procedures for these samples conform to the National Health (NiOSH) standards, institute of occupational Safety and

Air sampling was conducted at a level approximating the breathing zone of persons anticipated to be present In the area during normal operations. Samples collected should represent the area's typical airborne fiber concentration.

All samples were collected on fully exposed 25 millimeter, 0.8 micrometer (pm) cellulose ester membrane air sampling cassettes with conductive cowl,

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

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

Phase Contrast Microscopy JLC Environmental's laboratory uses an Olympus BH-PC Phase Contrast Microscope, (PCM) equipped with a Walton-Beckett Graticule. Samples were analyzed by first dissolving the filter through a chemical process (described above) and then counting the fibers with PCM at 400x magnification. Phase contrast increases the light contrast between the object and the background, thus enhancing the microscopist's ability to see fibers. Normally, 100 microscopic fields or 100 fibers are counted, whichever occurs first.

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

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