There are two types of asbestos microscopes: those for bulk fiber identification and those for asbestos fiber counting. Some microscopes can only be used for bulk fiber identification, while others can be used only for fiber counting. There are also several microscope models that can be used for both analysis methods. Read below to learn more about absestos analysis methods.
Asbestos bulk fiber identification uses polarized light microscopy for analysis. Asbestos bulk fiber identification microscopes meet the NIOSH 9002 standards for bulk asbestos fiber identification.
Methodology for polarized light microscopy analysis: NIOSH 9002
This method is useful for the qualitative identification of asbestos and the semi-quantative determination of asbestos in bulk samples. Polarized light microscopy measures the percentage of asbestos as perceived by the analyst in comparison to the standard projections, photographs or experience. The quality of the results are dependent upon the skill and judgement of the operator.
Asbestos fiber counting utilizes phase contrast microscopy for estimating asbestos concentrations of airborne fibers. Fiber counting microscopes meet the NIOSH 7400 and OSHA ID 160 requirements for asbestos fiber counting.
Methodology for phase contrast microscopy analysis: NIOSH 7400 & OSHA ID 160
Phase contrast microscopy is the method that is primarily used for estimating asbestos concentrations of airborne fibers. This method is quick and can be performed on-site for a rapid determination of cencentrations of asbestos fibers in the air. Phase contrast microscopy does not positively differentiate between asbestos and other fibers. Positive identification of asbestos fiber must be performed using polarized light microscopy (see above) or electron microscopy (method 7402).
