How Do You Test For Asbestos?

Feb 19, 2018

A common question we receive when clients are concerned about asbestos is “How do you test for asbestos?” In fact, there are many ways asbestos can be sampled. These methods include bulk, air, and dust sampling. In this blog post, I will go over these methods and how to decide which testing is best suited for your situation.

Bulk Sampling

Bulk sampling for asbestos refers to cutting out a small piece of the suspect material. This method is often employed when someone is concerned about a material, typically during a property transaction or renovation. The process of bulk sampling involves carefully collecting a piece of the material. It is imperative to disturb as little of the material as possible, as cutting it may cause asbestos fibers to become airborne. An asbestos inspector typically sprays the material with water amended with a surfactant such as dish soap prior to sampling to prevent fibers from getting into the air. The inspector will collect a sample using destructive methods to obtain a piece, typically around the size of a quarter. This may involve using a box cutter to cut out a piece of plaster or a coring device to cut into pipe insulation. The piece of suspect material is placed into a zip-locked bag and labeled for the laboratory.  The remaining surface can be patched, sealed, or covered to prevent future fiber release. Afterwards, the sample is sent to an accredited laboratory for testing.

In the laboratory, different types of microscopes evaluate if the material contains more than 1% asbestos. Materials containing more than 1% are considered “asbestos containing materials” and are typically regulated.  In a future blog, I’ll discuss the difference between the low cost, low sensitivity PLM (Polarized Light Microscopy) and the high cost, high sensitivity TEM (Transmission Electron Microscopy).

Air Sampling

A second method of testing asbestos is air sampling. Air testing is usually done when a potential asbestos-containing material has been disturbed or following asbestos removal to ensure that fibers weren’t released into the air during abatement. For example, air sampling would be suggested if walls were demolished in a home built before 1980 and the wall material was not sampled for asbestos. This may have lead to an accidental release of asbestos fibers. Another example would be after an asbestos material was abated, clearance air sampling would be necessary to ensure that fibers were not released during removal. The process is done by pumping air through a filter membrane about the size of a quarter to collect asbestos fibers. These tests typically run for up to 2 hours to achieve a total volume of up to 1,200 liters of air. Multiple air samples may be collected depending on the size of the project.

Dust Sampling

The final method we use to test for asbestos is dust sampling. This method is generally used to determine if there was a past release of asbestos fibers in an area. While asbestos can remain airborne for extended periods of time, it eventually settles into the dust. For example, if a past property owner did improper abatement work, there may be detectable levels of asbestos fibers in the dust even years later.

We are able to sample suspect dust by using a method called TEM microvac. This method involves using a TEM air cassette and vacuuming a 100 square centimeter area to evaluate the number of asbestos fibers present in the dust. Once collected and analyzed, we can use industry guidelines to observe if the number of asbestos fibers present are background, elevated, or highly elevated levels.


The wide variety of testing methods available allow for asbestos sampling in various scenarios. If you have a concern about asbestos, whether it be a material, air, or dust, Indoor Science has the capability to sample based on your concerns. We are licensed by the Illinois Department of Public Health, which is required to do asbestos inspections and testing. If you are interested in testing, feel free to reach out us at (312) 920-9393.