Forwarding WTC air monitoring scope for final review, Aug 2002

NYC 9/11 Public Portal Document

Environmental Protection Agency Pt. 763, Subpi. E, App. A (4) Matrix. Fiber or fibers with one end free ill. The micrograph number of the recorded and the other end embedded in or hidden by diffraction patterns must be reported to the a particulate. The exposed fiber must meet client and maintained in the laboratory's the fiber definition. quality assurance records. The records must (5) NSD. Record NSD when no structures also demonstrate that the Identification of are detected in the field. the pattern has been verified by a qualified (6) Intersection. Non-parallel touching or individual and that the operator who made crossing of fibers, with the projection having the Identification is maintaining at least an an aspect ratio 5:1 or greater. 80 percent correct visual Identification based 11. Structure Measurement. on his measured patterns. In the event that (1) Recognize the structure that Is to be examination of the pattern by the qualified sized. individual indicates that the pattern had (2) Memorize Its location In the "window” been misidentified visually, the client shall relative to the sides, inscribed square and to be contacted. If the pattern is a suspected other particulates in the field so this exact chrysotile, take a photograph of the diffrac­ location can be found again when scanning is tion pattern at 0 degrees tilt. If the structure resumed. is suspected to be amphibole, the sample (3) Measure the structure using the scale may have to be tilted to obtain a simple geo­ on the screen. metric array of spots. (4) Record the length category and struc­ J. Energy Dispersive X-Ray Analysis ture type classification on the count sheet (EDXA). after the field number and fiber number. 1. Required of all amphiboles which would (5) Return the fiber to its original location cause the analysis results to exceed the 70 s/ in the window and scan the rest of the field mm’ concentration. (Generally speaking, the for other fibers: If the direction of travel is first 4 amphiboles would require EDXA.) not remembered, return to the right side of 11. Can be used alone to confirm chrysotile the field and begin the traverse again. after the 70 s/mm’ concentration has b^n ex­ i. Visual identification of Electron Diffrac­ ceeded. tion (ED) patterns is required for each asbes­ 111. Can be used alone to confirm all non­ tos structure counted which would cause the asbestos. analysis to exceed the 70 s/mm^ concentra­ Iv. Compare spectrum profiles with profiles tion. (Generally this means the first four fi­ obtained from asbestos standards. The clos­ bers Identified as asbestos must exhibit an est match identifies and categorizes the identifiable diffraction pattern for chrysotile structure. or amphibole.) V. If the EDXA Is used for confirmation. 1. Center the structure, focus, and obtain record the properly labeled spectrum on a an ED pattern. (See Microscope Instruction computer disk, or If a hard copy, file with Manual for more detailed Instructions.) analysis data. ii. From a visual examination of the ED vi. If the number of fibers In the non­ pattern, obtained with a short camera asbestos class would cause the analysis to length, classify the observed structure as be­ exceed the 70 s/mm’ concentration, their longing to one of the following classifica­ Identities must be confirmed by EDXA or tions: chrysotile, amphibole, or nonasbestos. measurement of a zone axis diffraction pat­ (1) Chrysotile: The chrysotile asbestos pat­ tern to establish that the particles are non­ tern has characteristic streaks on the layer asbestos. lines other than the central line and some k. Stopping Rules. streaking also on the central line. There will 1. If more than 50 asbestlform structures be spots of normal sharpness on the central are counted In a particular grid opening, the layer line and on alternate Unes (2nd. 4th. analysis may be terminated. etc.). The repeat distance between layer lines 11. After having counted 50 asbestlform is 0.53 nm and the center doublet is at 0.73 structures in a minimum of 4 grid openings. nm. The pattern should display (002). (110). the analysis may be terminated. 'The grid (130) diffraction maxima: distances and ge­ opening In which the 50th fiber was counted ometry should match a chrysotile pattern must be completed. and be measured semlquantitatlvely. 111. For blank samples, the analysis Is al­ (2) Amphibole Group [Includes grunerite ways continued until 10 grid openings have (amosite), crocidolite, anthophyllite, tremo­ been analyzed. lite. and actinolite]: Amphibole asbestos iv. In all other samples the analysis shall fiber patterns show layer Unes formed by be continued until an analytical sensitivity very closely spaced dots, and the repeat dis­ of 0.005 s/cm’ is reached. tance between layer Unes is also about 0.53 1. Recording Rules. The count sheet should nm. Streaking in layer Unes is occasionally contain the following Information: present due to crystal structure defects. i. Field (grid opening): List field number. (3) Nonasbestos: Incomplete or unobtain­ 11. Record "NSD” If no structures are de­ able ED patterns, a nonasbestos EDXA, or a tected. nonasbestos morphology. ill. Structure Information.

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NYC-WTC_000139312