Environmental assessment request letter, February 2002

NYC 9/11 Public Portal Document 02/20/2002,_Q LU FAX lit 004

Insignia Residential Group, Inc. JLG Project #01-2094 Septbmber 20, 2001 ,age 2 Air Samplings Analysisand Procedure

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

Methodology Test procedures for these samples conform to the National Institute of Occupational Health (NIOSH) standards. 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.

J Analytical Procedures A section of the filter approximating twenty-five percent of the total filter was removed and placed on a pre-cleaned microscope slide and then exposed to approximately 250 microliter (pl) of 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 filter. The prepared slide was then heated on a slide heater until be conducted. clarity allowed analysis to

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 811-PC Phase Contrast Microscope, (PCM) equipped with a Waiton-Beckett Graticule. Samples were analyzed by first through a chemical process (described above) and then counting the fibers dissolving the filter with PCM at 400x magnification. Phase contrast increases the light contrast between the object and thus enhancing the microscopists ability to see fibers. Normally, 100 the background, fibers are counted, whichever occurs first microscopic fields or 100

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

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