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

NYC 9/11 Public Portal Document

DEC. 3.2001 12:07PM JLC ENVIRONMENTAL NO.157 P.8

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

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

1Methodology Test procedures for these samples conforjnto the National Institute of Occupational Safety and Health (NIOSH) standards.

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. i?

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

Analytical Procedures A section of the filter approximating twenti-five percent of the total filter was removed and placed on a pre-cleaned microscope slide and then xposed to approximately 250 microliter (pi) of acetone vapor. A single 3.0 - 3.5 pI drop of triacetin was applied and a clean #1.5 cover slip was placed upon the filter. The prepared slide was then heated on a slide heater until clarity allowed analysis to be conducted. F Analysis was accomplished utilizing a Ph Contrast Microscope in accordance with NIOSH 7400 method, counting rule "A."

Phase Contrast Microscopy JLC Environmental's laboratory uses an C (mpus SH-PC Phase Contrast Microscope, (PCM) equipped with a Walton-Beckett Graticule Samples were analyzed by first dissolving the filter through a chemical process (described ah and then counting the fibers with PCM at 400x ve) L, magnification. Phase contrast increases 1 e light contrast between the object and the background, thus enhancing the microscopists ability t, see fibers. Normally, 100 microscopic fields or 100 fibers are counted, whichever occurs first.

Results ;.. The "Summary of Analytical Results" reprf cents the results of the analysis of the samples.

The, ' PCM limit of reliable quantification is less t ian 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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