Chain of custody form, 21 West Street, Nov 2001

NYC 9/11 Public Portal Document FEB-28-2002 THU 11:10 AM CLOSINGS 4 ROSE FAX NO. 212 210 6724 P. 21/42

Rose Associates Inc. JLC project #01-2089002 n + ctober 16, 2001 . page ? AI Sannpting Analysis and Proctadure

Introduction Air sampling is defined as the process of measuring the filter content of a known volume of air entrained on a filter 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.

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

Air snmpiing was conducted at a level approximating the broathing 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 sampiin0 cass~tte with nnndantive cowl.

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 (i.il) 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 clarity ulluwed art~tlysis to be conducted.

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

Phase Contrast Microscopy JLC Iwnvironmental's laboratory uses an Olympus BH-PC Phase Contrast Microscope, (PCM) equipped with a Walton-Beckett Graticuls. Samples were analyzed by first dissolving the filter through a chemical process (described above) dnd their euunting 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.

ti. 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 fiberslcubic centimeter (ficc) of air. If final tests do not meet these requirements, the entire work site must be re-cleaned and re-tested,

NYC-WTC 000094613