We recently have removed old vinyl flooring and the people that performed the abatement did a pre, during and post clearance air tests using the PCM method.

The pre and post tests resulted in 0.016 f/cc and 0.007 f/cc. The test ran for 1200 liters of air as volume and in the pre-removal test the fiber count was 40 whereas the fiber count for the clearance was 15.

What I cannot understand is that the two numbers when converted are not compatible. For example 40/1200 results in 0.03 f per liter of air. However the result provided (0.016 f/cc) if converted to liters is 0.016*1000 (a liter contains 1000 cubic centimeters) = 16 fibers per liter.

Is there something that I am missing? Is it reasonable to expect that my space has thousands as opposed to hundreds of fibers?

PS: I am aware that PCM does not distinguish between asbestos and non-asbestos fibers so the actual counts may be 10% or 50% or some percentage of the original fiber count.

  • What is the fiber size? If that is not specified and the ratio of sizes the test sounds like a waste of $. I worked in clean rooms for many years and the size can be more important in some cases than the quantity.
    – Ed Beal
    Sep 12, 2019 at 16:36
  • Here is the additional info that they had in the report: Fields: 100, Blank Avg: 0, LQL: 0.0321, LOD: 0.0022. LQL = Lower Quantitation Limit, LOD Analytical Detection Limit. Microspocpe field area: 0.00785
    – Michael
    Sep 15, 2019 at 14:52


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