Images of asbestos fibers taken by scanning electron microscopy (SEM).
Credit: J. Holm/NIST
For decades, a laboratory procedure known as transmission electron microscopy (TEM) has been used to test for asbestos in samples taken at construction sites.
In 1989, the U.S. Environmental Protection Agency (EPA) required most schools undergoing asbestos abatement to use TEM to test for the presence of asbestos fibers in air samples before reopening. Several states require or recommend using TEM for testing as part of asbestos removal in commercial buildings.
But TEM must be carried out in a specialized lab by highly trained staff and can be expensive. Another approach, phase contrast microscopy, is easier and cheaper but less precise.
Now, researchers at the National Institute of Standards and Technology (NIST) have determined that a third option, scanning electron microscopy (SEM), can achieve results roughly comparable to TEM. SEM is a “viable alternative to the current regulatory methods for asbestos identification and classification,” the NIST researchers Jason Holm and Elisabeth Mansfield wrote in a new paper published in Analytical Methods.
Since SEM is, in many cases, cheaper and more convenient than TEM, the finding could potentially speed up and reduce the expense of asbestos remediation in the United States, which costs an estimated $3 billion every year.
Asbestos is a naturally occurring mineral whose fibers were used for insulation, weather- and fire-proofing and reinforcing building materials. Its use began declining in the 1970s as resea ..
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