Even though asbestos products were banned in the United Kingdom in 1999, nearly half of all buildings – and upwards of 75% of schools – still contain this carcinogenic material. If asbestos products are damaged, their sharp microscopic fibres are released into the air. When inhaled, asbestos can embed itself in the lungs.
With proper detection of airborne asbestos fibres, fatal diseases like asbestosis and mesothelioma can be avoided, as well as asbestos-related conditions like pleural thickening and other lung disorders. With nearly 2000 British citizens succumbing to asbestos-related diseases each year, it is clear that more must be done.
Over 30 different methods are used in order to determine asbestos contamination in air, water, dust, soil and products. However, there are three air tests for asbestos fibres that British experts rely on to determine contamination: Phase contrast microscopy (PCM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM).
What is the main airborne asbestos test used in the UK?
In England, PCM is often used to determine the concentration of asbestos fibres in the air, especially when there is concern regarding how much loose asbestos a person has been exposed to. In this method, air is drawn through a filter, and the fibres are then measured in each millilitre of air.
Regrettably, PCM cannot distinguish whether fibres are asbestos or any other material, and this is not the clearest way to gather information specifically related to asbestos exposure. For example, a barn will understandably contain more fibres than a factory with adequate exhaust fans. Additionally, when incredibly small asbestos fibres are released into the air, they may be too small to be detectable by PCM.
How do SEM and TEM compare to PCM?
Asbestos air testing in the form of SEM and TEM is incredibly reliable for accurate readings, even in lower exposures to the substance. SEM and TEM enable the clear identification of asbestos and non-asbestos materials and are certainly more accurate (especially when asbestos fibres are present in smaller amounts) than PCM.
SEM and TEM, however, are less than ideal due to the extended wait times to receive results. Both typically require asbestos sample testing to be sent away to a laboratory, so the hour window required for PCM readings is often preferable, especially in emergency situations.
How is fluorescence microscopy (FM) used in asbestos testing?
In recent years, FM has become an increasingly promising scientific tool, allowing us to examine single molecules in a variety of endeavors. For asbestos detection, FM uses an E. coli-derived protein, DkSA, which attaches itself to chrysotile fibres, essentially staining them with a substance that will fluoresce under specific conditions. Since chrysotile asbestos is the most commonly found asbestos type in the UK, this breakthrough is of tremendous importance.
Unlike PCM, the FM test ideally only latches onto these specific asbestos fibres. While more testing needs to be done to ensure that this protein attaches only to chrysotile to avoid false positives and negatives, much research and development has already been done to overcome this issue
A U.S. National Institutes of Health study found that by combining both FM and SEM testing, FM shows clear potential in identifying all countable chrysotile asbestos fibres without requiring lengthy laboratory tests. Additionally, the study showed that FM can detect fibres nearly ten times smaller than PCM testing, and “approaching the sensitivity of scanned electron microscopy (SEM).”
FM image processing software is also being developed to automate fibre calculation. Determining fibre levels quicker, more accurately and with portability will likely be the reason that FM becomes the industry standard over the coming years.
What is the hold-up with FM testing?
Aside from more research being needed, the major hurdle of introducing FM testing into the mainstream comes down to current Control Limit and Clearance Indicators, which were designed with PCM limits via the HSE and HSL. The biggest reason that FM has not yet become the industry standard comes down to PCM being the world standard benchmark of airborne asbestos testing.
Now that more accurate asbestos fibre testing for air quality is available, regulatory standards will need to be altered for the first time in decades, along with new guidelines and updated training. The value of this shift cannot be understated, however, and the anti-asbestos community looks forward to the advancement of this technology.
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