Understanding PLM and TEM Asbestos Testing

Elyse Aufmann • January 4, 2022

Asbestos was a popular building material until the mid-20th century; asbestos is a compound that was used between walls as insulation to keep a home warm during the winter. While many modern houses use alternative materials for insulation, many older homes still contain some fragments of asbestos. If you live in an older home, you need to run a test to determine if your home has asbestos. At Air Safe Inc., we use PLM and TEM testing. Here’s a guide to understanding PLM and TEM asbestos testing.


How We Collect Samples

We need to search an entire home for signs of asbestos before deciding on specific spots to collect potential samples. For instance, we go into ceilings and walls to collect plaster and check the attic, which often contains pipe bits.


By methodically accumulating samples, we no longer need to worry about having a paucity of information when inspecting a home.


While looking for samples, we target areas where clients suspect asbestos might linger, but we also perform complete assessments of aged homes to find other spots that are potentially contaminated.


PLM Testing

The acronym PLM stands for polarized light microscopy, which inspects building materials. In other words, when we do a PLM test, we sort through piles of building debris to collect data on fibrous properties. The collected data tells us the percentage of asbestos in the material.


PLM Point Count

The PLM point count refers to the type of asbestos detected and how much was contracted from the material. Even though we use the PLM test to see the actual asbestos, PLM point count finds the type of asbestos, adding the percentage recorded to the physical total.


PLM Gravimetric Point Count

Our gravimetric point count uses a furnace with acids to form its sample and find a percentage. It then compares it to the point count percentage.


TEM Testing

A TEM test, which stands for transmission electron microscopy, confirms small or low traces of asbestos concentrations. The concentrations come from tested building materials and other organically bound materials.


TEM Air AHERA

TEM air AHERA is a test used in commercial buildings and schools. The test detects any final remnants of asbestos and helps give the last call to reopen a building as long as there’s no trace of asbestos or other types of harmful fibers hanging in the air.


As you build your understanding of PLM and TEM asbestos testing, it’s imperative to reach out to Air Safe Inc. for asbestos abatement in MA. Our services provide the best and most trustworthy EPA-approved testing.


Furthermore, we want you to stay safe in your home and business. If you plan to make improvements to older homes or businesses or plan to purchase a new property, we recommend scheduling an inspection before buying or renovating.



At Air Safe Inc., we pride ourselves on using the best methods to test and remove signs of asbestos or other harmful fibers. For more information on asbestos abatement services, contact us here.

A residential entrance enclosed in translucent plastic sheeting, with bags, rolled materials, and a
By Ryan Gallagher • October 22, 2026
Found asbestos in your home? Removal may not be the only option. Understand how abatement and encapsulation relate and what could affect your next steps.
A close-up of coarse vermiculite granules spread across a flat surface, showing their layered textur
By Ryan Gallagher • October 9, 2026
Before vermiculite removal begins, the wrong prep can create unnecessary risks. Find out how to get your home ready while leaving suspect insulation untouched.
A person holding a magnifying glass over corrugated roofing material with broken edges
By Ryan Gallagher • September 25, 2026
When suspect materials raise questions, guessing can complicate your next move. Learn when professional asbestos testing can give you clearer answers.
A large metal dumpster filled with broken construction debris, white bags, wood pieces, and loose ma
By Ryan Gallagher • September 14, 2026
Not sure where asbestos waste can legally go in Massachusetts? See what homeowners should know before arranging compliant removal and disposal.
A close-up of a man wearing a face mask and gloves, inspecting a wall with peeling paint and damage
September 10, 2026
Planning asbestos work in Massachusetts? Learn how the 10-day notification rule affects your timeline and what to expect before your project can begin.
Two people sitting on a light couch with documents.
By Ryan Gallagher • August 6, 2026
Found vermiculite insulation in your attic? There's an important program to know about. See how your home can benefit from the Zonolite Trust.
A person in a white protective suit placing debris into a black bag inside a room with tools.
By Ryan Gallagher • July 28, 2026
Cutting corners on asbestos removal in your home can cost far more over time. Discover the risks of improper removal and the value of doing it right.
Two men in coveralls and respirator masks adjust their protective gear as they stand by the doorway
July 22, 2026
Asbestos fibers can become airborne during renovations in some properties. See how HEPA filtration helps improve safety and containment efforts.
An extreme close-up of a broken ceramic floor tile revealing asbestos and surrounding damage to the
By Ryan Gallagher • July 15, 2026
Older flooring may hold clues that deserve a closer look before your next renovation. Hidden details beneath aging tile could affect your plans.
A close-up of a dual LED bulb light fixture with a glass cover mounted on a speckled popcorn ceiling
June 17, 2026
Questions about older textured ceilings continue to concern homeowners. Key safety considerations shape testing decisions before renovations begin.