Environmental assessment request letter, February 2002

NYC 9/11 Public Portal Document 02/20/2002 09:27 FAX iJ 062

Mazal Group LLC (100 John Street) JLC Project # 01-2084 December 11, 2001 page 2 AIr SamDllnp Analysis and Proceduj

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

Methodology Test procedures for these samples conform to the National Institute of Health (NiOSH) standards. 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 typical airborne fiber concentration. represent the area's

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 a pre-cleaned microscope slide and then exposed to approximately 250 microliter (NI) and placed on 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.

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

Phase Contrast Microscopy JLC Environmental's laboratory uses an Olympus BH-PC Phase Contrast equipped with a Walton-Beckett Graticule. Samples were analyzed by firstMicroscope, (PCM) 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 thus enhancing the mlcroscopisfs ability to see fibers. Normally, 100 and the background, microscopic fields or 100 fibers are counted, whichever occurs first.

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

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