Point-Countering

Question: I am confused. When does the EPA NESHAP standard actually require me to perform point-counting rather than ordinary PLM analysis?

Situation

An inspector has collected samples for analysis and needs to know whether or not to have the laboratory conduct the more expensive point-counting PLM rather than ordinary PLM.

Recommendations

Have all materials ("homogeneous areas") analyzed by ordinary PLM and have the worst-case sample for each material checked by PLM for which the results meet the following criteria:

  • The material is friable.
  • The material has some asbestos.
  • You want to show that the material is not ACM.

In addition, you may want to (but are not required to) have the worst-case sample of each nonfriable materials analyzed by point-counting PLM if it has more than 1% asbestos content but you want to make sure that it is ACM.

(See the Work Plan below for additional detail.)

Analysis

The Law: The EPA NESHAP (40 CFR 61.141) defines friable asbestos material as "any material containing more than 1 percent asbestos as determined using the method specified in appendix E, subpart E, 40 CFR 763, section 1, Polarized Light Microscopy, that, when dry, can be crumbled, pulverized, or reduced to powder by hand pressure. If the asbestos content is less than 10 percent as determined by a method other than point counting by polarized light microscopy (PLM), verify the asbestos content by point counting using PLM. (emphasis added)" There is no similar point counting requirement written into the definition of nonfriable ACM.

The Issue: The EPA was concerned that an analyst might consistently underestimate the amount of asbestos in a friable sample when "eyeballing" it under the scope. The point count method minimizes much of this estimation error and provides a higher probability of having the right estimate of asbestos content.

However, the EPA--after publishing this standard--noted that you do not need to point count all friable samples with less than 10% because:

  1. if there is no detectable fiber, point counting won't make it appear;
  2. if there is more than about 6-8%, it is likely to point count above 1.0% so the building owner can simply assume that it is ACM and not request point counting, and
  3. the standard only requires point-counting the worst case (that is, verifying its asbestos content), since if it is >1%, all samples in the homogeneous area must be considered ACM and if it is not >1%, all other samples must also be below this cutoff

The Work Plan

To assist our training clients, we have developed a laboratory instruction letter to make this easier to implement. Click here to get a copy (PDF Format. Acrobat Reader may be required). Since we have used this letter for several years, many laboratories in this area are familiar with this protocol.

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