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3648141 
Journal Article 
MSHA Standard Method For Fiber Identification B Electron Microscopy 
Clark, RL 
1982 
NIOSH/00145884 
619 
619 
207-210 
The Mine Safety and Health Administration (MSHA) standard method for the analysis of airborne particulates is reviewed. A phase contrast microscopy method is specified for use in obtaining gross fiber counts for each sample filter. Electron microscopy is utilized to obtain a physical characterization of the analyte material and to make an analytical determination of the nature of specific components of the analyte. Physical characterization is made by a computer assisted image analysis system. Analysis is achieved by the classification of individual fibers based upon the crystallographic data contained in selected area electron diffraction patterns in combination with elemental compositional data derived from energy dispersive X-ray spectrometry. Results from optical and electron microscopy are combined to yield the number of asbestos (1332214) fibers per unit of air. Specimen preparation is described. In contrast to the Environmental Protection Agency (EPA) provisional method, cellulose acetate membrane filters are employed for sample collection. Removal of filter sections for optical microscopy, testing of blank specimens, and choice of grid materials and mesh sizes are discussed. Examination of the specimens in a scanning transmission electron microscope is described. Differentiation between asbestiform amphibole minerals and associated non asbestos minerals is considered. If either of the two identification criterion of positive selective area electron diffraction pattern as asbestiform amphibole or a fit of the energy dispersive X-ray spectra to the published compositional data are not achieved, then the fiber cannot be identified as asbestos. The author concludes that the MSHA method is an alternate but viable analytical method which evolved in response to a specific set of circumstances other than those imposed in the development of the EPA provisional methodology. 
DCN-133111; Analytical processes; Electrophysiology; Analytical instruments; Ergonomics; Standards; Work environment; Analytical methods; Workers; Regulations; 1332-21-4