NIOSH Method 9002

NIOSH Method 9002 is the National Institute for Occupational Safety and Health's method for identifying asbestos in bulk materials such as insulation, tile or debris using polarized light microscopy. It identifies the asbestos type from optical properties and gives a semi-quantitative estimate of how much is present, with a practical lower limit of about 1 percent.

Origin

The method is part of the NIOSH Manual of Analytical Methods, which publishes standardized sampling and lab methods for workplace hazards; it was issued and revised in the late 1980s and 1990s. It parallels EPA's bulk-sample method and relies on the same optical tests, including refractive index, dispersion staining and sign of elongation.

Significance in Asbestos Context

Many workplace and building surveys report bulk results under NIOSH 9002 or the similar EPA method, and these reports often become evidence that a product or building material contained asbestos. Because it is a light-microscope method, NIOSH 9002 can miss very fine fibers, and its estimates of percentage are approximate; NIOSH itself notes that it is mainly a qualitative identification method. A result of "none detected" under this method does not rule out asbestos at low levels or in very fine form, especially in floor tiles, mastics and other materials where fibers are bound in resin. When the amount of asbestos is in dispute, experts often turn to point counting, gravimetric preparation or electron microscopy for more precise numbers.

Example Sentence

The 1991 survey analyzed the pipe insulation under NIOSH Method 9002 and found 30 to 40 percent amosite.

Related Terms

NIOSH, Polarized Light Microscopy (PLM), Bulk Sample Analysis, EPA Method 600-R-93-116, dispersion staining, Visual Area Estimation, PLM Detection Limit

Notes

• Old survey reports often name the method used; that tells an expert how much weight to give the result.
• A negative PLM result on floor tile or mastic may need confirmation by electron microscopy.