Ambient air sampling report, 333 Rector Place, Sep 2001

NYC 9/11 Public Portal Document NOV. 1S.2O 1 5:41PM JLC ENVIRONMENTAL NO.752 P.3/14

Milford Management Corp. page 2 JLC Project #01-2200 BulkBuildinq Materials Analysis and Procedure

introduction Polarized light microscopy with dispersion staining (PLM-DS) is the most efficient method for detecting asbestos in bulk samples. it is this method that the JLC lab uses during bulk building material analyses.

Methodology A chain of custody is kept for each sample to ensure proper handling and delivery to the JLC lab prior to analysis. To avoid any possible contamination, all sample and slide preparation is carried out in a ventilated, HEPA-filter hood with continuous airflow. Sample analysis is performed using PLM-DS in accordance with the USEPA , "Method for the Determination of Asbestos in Bulk Building Materials." EPA 600 R-93 116, July 1993, and NYDOH-ELAP certification manual, "Polarized Light Microscope Methods for Identifying and Quantitating Asbestos in Bulk Samples," ELAP 198.1, October 1993.

Analytical Procedures All samples are subject to preliminary visual stereomicroscopic examination. Observation of homogeneity, fiber identification, and semi-quantitation of constituents can be made at this point. Samples lacking uniformity of composition and/or distribution of component materials then undergo homogenization. Some non-friable organically bound (NOB) samples such as floor tiles and roofing materials may require additional steps to dislodge problem matrices (i.e. ashing, extractions, and TEM).

Identification of suspect fibers is made by PLM analysis of subsamples. A microscope equipped with dual polarizing filters enables us to observe specific optical characteristics of each sample. Positive identification of asbestos requires determination of the following optical properties: morphology, color and pleochroism, refractive indices, birefringence. extinction characteristics, and signs of elongation.

Asbestos quantitation is performed by point-counting procedure, a standard technique in petrography for determining the relative areas occupied by separate minerals in rock. An ocular reticle superimposes a point or points over the microscope's field of view. The number of points positioned directly above each kind of particle or fiber is recorded. A total of 400 points must be counted over at least eight different representative subsamples to complete analysis.

Polarized Light Microscopy JLC uses an Olympus BHT-P Polarizing Microscope complete with polarizer, analyzer, port for wave retardation plate, 360 degree graduated rotating stage, substage condenser, lamp and lamp iris, eyepiece reticle, and 25 point Chalkley Point Array. Plane polarized light allows for the determination of refraction indices relative to specific crystallographic orientations. Morphology and color can also be observed under plane polarized light. Observation of particles or fibers while oriented between polarizing filters whose privileged vibration directions are perpendicular allows for determination of isotropism/ anistropism, extinction characterisitcs of anisotropic particles, and calculation of birefringence. A retardation plate may be placed in the polarized light path for verification of signs of elongation.

Analytical Results The "Summary of Analytical Results" represents the results of analysis. Positive results mean the sample is asbestos or contains more than one percent asbestos by weight. The results are generally sufficient for identification and quantitation of major concentrations of asbestos. However, it may be found that additional techniques may be necessary. Please be aware that PLM is not consistenly reliable in detecting asbestos in floor coverings and similar NOB materials. Before the material can be considered or treated as non-asbestos containing, confirmation must be made by quantitative Transmission Electron Microscopy (TEM).

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