Forwarding WTC air monitoring scope for final review, Aug 2002

NYC 9/11 Public Portal Document

Environmental Protection Agency Pt. 763, Subpt. E, App. A an accredited Inspector under para­ with each fiber closer than one fiber diame­ graphs (a) (3), (4), (5) of this section, or ter. an architect, project engineer or ac­ 5. Clean area—A. controlled environment which is maintained and monitored to assure credited Inspector under paragraph a low probability of asbestos contamination (a)(7) of this section, the local edu­ to materials in that space. Clean areas used cation agency shall have 180 days fol­ in this method have HEPA filtered air under lowing the date of identiflcatlon of positive pressure and are capable of sus­ ACBM to comply with this subpart E. tained operation with an open laboratory blank which on subsequent analysis has an Appendix A to Subpart E—Interim average of less than 18 structures/mm^ in an Transmission Electron Micros­ area of 0.057 mm’ (nominally 10 200-mesh grid copy Analytical Methods—Man­ openings) and a maximum of 53 structures/ mm’ for any single preparation for that same datory and Nonmandatory—and area. Mandatory Section to Determine 6. Cluster—A structure with fibers In a ran­ Completion of Response Actions dom arrangement such that all fibers are Intermixed and no single fiber is Isolated I. Introduction from the group. Groupings must have more The following appendix contains three than two intersections. units. The first unit is the mandatory trans­ 7. £O—Electron diffraction. mission electron microscopy (TEM) method 8. EDXA—Energy dispersive X-ray anal­ which all laboratories must follow; it is the ysis. minimum requirement for analysis of air 9. Fiber—A structure greater than or equal samples for asbestos by TEM. The manda­ to 0.5 gm in length with an aspect ratio tory method contains the essential elements (length to width) of 5:1 or greater and having of the TEM method. The second unit con­ substantially parallel sides. tains the complete non-mandatory method. 10. Grld—^ open structure for mounting The non-mandatory method supplements the on the sample to aid In Its examination in mandatory method by including additional the TEM. The term is used here to denote a steps to improve the analysis. EPA rec­ 200-mesh copper lattice approximately 3 mm ommends that the non-mandatory method be In diameter. employed for analyzing air filters: however. 11. Intersection—Nonparallel touching or the laboratory may choose to employ the crossing of fibers, with the projection having mandatory method. The non-mandatory an aspect ratio of 5:1 or greater. method contains the same minimum require­ 12. Laboratory sample coordinator—That per­ ments as are outlined In the mandatory son responsible for the conduct of sample method. Hence, laboratories may choose ei­ handling and the certification of the testing ther of the two methods for analyzing air procedures. samples by TEM. 13. Filter background level—The concentra­ tion of structures per square millimeter of The final unit of this Appendix A to sub­ filter that is considered indistinguishable part E defines the steps which must be taken from the concentration measured on a blank to determine completion of response actions. (filters through which no air has been This unit is mandatory. drawn). For this method the filter back­ II. Mandatory Transmission Electron ground level is defined as 70 structures/mm’. Microscopy Method 14. Matrix—Fiber or fibers with one end free and the other end embedded in or hidden A. Definitions of Terms by a particulate. The exposed fiber must meet the fiber definition. L Analytical sensitivity—Airborne asbestos 15. NSD—No structure detected. concentration represented by each fiber 16. Operator—A person responsible for the counted under the electron microscope. It Is TEM Instrumental analysis of the sample. determined by the air volume collected and 17. PCM—Phase contrast microscopy. the proportion of the filter examined. This 18. SAED—Selected area electron diffrac­ method requires that the analytical sensi­ tion. tivity be no greater than 0.005 structures/ 19. SEM—Scanning electron microscope. cm’. 20. STEM—Scanning transmission electron 2. Asbestiforai—A specific type of mineral microscope. fibrosity in which the fibers and fibrils pos­ 21. Structure—a microscopic bundle, clus­ sess high tensile strength and flexibility. ter, fiber, or matrix which may contain as­ 3. Aspect ratio—A ratio of the length to the bestos. width of a particle. Minimum aspect ratio as 22. S/cnP—Structures per cubic centimeter. defined by this method is equal to or greater 23. S/mm’-'-Structures per square milli­ than 5:1. meter. 4. Bundle—A structure composed of three 24. TEA#—Transmission electron micro­ or more fibers in a parallel arrangement scope.

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NYC-WTC_000139284