Asbestos, once hailed as a miracle material for its fire-resistant properties, is now widely recognised as a serious health hazard. Inhaling asbestos fibres can lead to severe respiratory conditions, ranging from lung cancer to long-term mesothelioma, which has exclusively been linked to asbestos exposure.
Many people think about sampling building materials for asbestos, and this is an important step before beginning work. But if asbestos is found in a given sample and must be removed, it’s vital to monitor the air during work to prevent exposure. That’s where asbestos fibre counting comes in.
Read on as we explore what asbestos fibre counting is, the different techniques that fall under this umbrella, and which one is right for your needs.
What is Asbestos Fibre Counting?
Asbestos fibre counting is a method for asbestos sampling and testing, generally referring to airborne fibre sampling. Air sampling machines are set up while construction or demolition work is occurring. The machines pipe air through inputs, sending the airflow through a membrane that’s designed to capture any lingering asbestos fibres on its surface.
That membrane is extracted and tested using one of several microscopy techniques (which we will outline later). Essentially, technicians count the number of fibres present on the membrane and extrapolate the level of contamination from there.
It’s important for the air pumps to draw an established quantity of air over a designated amount of time, as this allows lab technicians to define how much asbestos is in the air by counting the fibres.
The Different Asbestos Fibre Counting Methods
There are three main asbestos fibre counting methods. All of these work by collecting air over a defined length of time, usually using machines on-site, and then extracting the membrane for analysis.
Phase Contrast Microscopy (PCM)
This technique involves collecting samples on a filter and examining them under a microscope that enhances the contrast of the fibres against the background of the filter.
This is the most commonly-used technique for air sampling, and is generally less expensive than most other methods. This makes it a popular choice for routine monitoring while work is ongoing. It’s also fast-acting, providing results in a short time.
While this can’t differentiate between fibre types, it can let us know that there is asbestos in the air (and how much there is), which is ideal for baseline safety during construction or demolition.
Generally speaking, this technique is best for routine monitoring because it requires less intensive equipment. When you work with the Consultex Labs team, our mobile asbestos laboratory uses this technique to assess the air for fibres and ensure work can continue safely.
Transmission Electron Microscopy (TEM)
If asbestos fibres are detected in the air, we might use this next method to re-count how many fibres are in the air, as this method is even more sensitive than PCM. This method also allows technicians to identify the type of asbestos fibres captured in an air sample, providing more specific data.
This more complex analysis can take time and requires more heavy duty equipment, which is why it is only generally employed once asbestos fibres are detected with the PCM technique.
Generally speaking, this technique is best if you have had asbestos removed from your property, and you’re looking to verify that all asbestos is gone.
Scanning Electron Microscopy (SEM)
This method is similar to TEM, but it uses a different kind of electron beam to scan the sample’s surface. This ensures our lab technicians can access more detailed images, allowing them to distinguish between different fibre types as part of testing.
While this technique is not as suitable for routine monitoring, it’s a great choice for when you need deeper information about the fibre’s type, morphology, and condition. On top of that, it’s often employed for complex contamination scenarios (for example, if there are multiple types of asbestos, or multiple substances in a given sample).
Generally speaking, this technique is usually employed for solid samples, such as soil or building materials, though it can also be used for airborne fibre counting when the situation calls for it.
Deciding which technique is best for your property will rely on what the purpose of the sampling is. For example, if you’re looking for a technique to routinely monitor a construction site while work is ongoing, a simple PCM test will suffice. But if the situation is more complex, or you’re looking for more information on the type of asbestos, we might recommend TEM instead.
While these are general guidelines, the best thing to do if you are unsure is to get in touch with your local asbestos testing laboratory for guidance on your next steps.
Get quick, accurate asbestos sampling and fibre counting with the team from Consultex Labs.
Our team of qualified, independent, IANZ-accredited technicians are on standby to test any samples from your property. We offer same-day urgent turnaround, equipment hire for air sampling, and even a mobile asbestos testing laboratory for on-site work.
Unsure what you need for your property? Get in touch with us today to get started.