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There are several analytical techniques within the realm of asbestos sampling. The most general way to test for asbestos-containing material is through Polarized Light Microscopy. PLM is used to detect asbestos in a “bulk” sample, such as a piece of floor tile, wall texture, hard plaster, or pipe insulation, etc. PLM is the most accepted method for initial analysis of bulk building materials for asbestos content. But there are methods we can use to get a more precise result.


Why Use Point Counting When Testing for Asbestos?

When a bulk sample of material is found to contain 10% asbestos or less, the sample may be presumed to contain greater than 1% asbestos and treated as such or, the sample can be further analyzed via point counting or Transmission Electron Microscopy.

These additional steps can be employed to more accurately determine the percent of asbestos that is in the material being sampled. Additionally, samples analyzed via PLM frequently are determined to contain “trace” amounts of asbestos, usually written as less than 1% asbestos.  Any sample determined to contain less than 1% asbestos must be point counted to prove it contains less than 1%. Typical materials that are candidates for point count analysis are friable materials like drywall-joint compound, ceiling or wall texture, hard plaster, etc. 

Non-friable materials such as floor tile, roofing materials and their associated mastic binders are not good candidates for point count analysis. They are better analyzed by gravimetric point count methods or using TEM analysis. Like point counting for friable materials, this approach provides a more precise result than the initial PLM analysis.

The main purpose to point count (or TEM) a certain material is to find out if it contains less than 1% asbestos since anything 1% or less is legally considered “non-asbestos containing.” If point counting/TEM is not used, many materials could be mistakenly considered to contain more than 1% asbestos. This mistaken assumption could lead to an expensive and time-consuming asbestos remediation project that could otherwise be avoided.

If the analyst detects asbestos in the sample and estimates the amount by visual estimation to be less than 10%, the owner or operator of the building may do one of the following:

  1. Elect to assume the amount to be more than one percent and treat the material as an asbestos containing material.
  2. Require verification of the amount by point counting. If a result obtained by point count is different from a result obtained by visual estimation, the point count result will be used.

Point counting and TEM cost a little more to analyze, but this more detailed analysis could save significant money in abatement fees.

Tioga’s scientists are available to answer any questions you may have about point-counting and TEM. We look forward to helping you with your asbestos needs. Learn more about our expertise in hazardous building materials and contact our team today.