Classification Guide
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Dust Extractor Classes
When working in a dusty environment with materials that generate dust, your main priority needs to be protecting your health!
Avoiding as much dust as possible is a good general rule, applying some best practrices to reduce the amount of dust created is an important step
Things that can be done to reduce dust inhalation include:
Changing tools being used to cut, saw and grind to minimise dust created in the first case by using tools which offer complete dust control during cutting and grinding
Protecting workers with full PPE and respiratory wear
Using dust extractors
Sectioning off dangerous areas of the workspace to reduce the risk of crowded inhalation
There are different types of dusts that range from low risk to high risk and it's important to understand what they are and why.
There are three main factors that determine how harmful dust is to your health:
- The size of the dust particles
- The quantity
- The time that the materials remain inside your lungs
The smaller the dust particles are, the deeper they can penetrate into the lung tissue, meaning finer dust particles are much more harmful to your airways.
Many dust particles are even categorised as extremely hazardous to health. For example, crystalline silicon dioxide is closely associated with the development of lung cancer.
In the interests of your own health and others around you, it is imperative that you keep the air clean when generating dust from using power tools and always work with a certified and approved dust extractor. When buying power tools and/or extractors, you will find that they are designed for use with various types of dust. Instead of taking your chances, always make sure you know what classes of dust you are likely to be working with.
There are three main classes of industrial dust you should be aware of. These are ranked based on the particle size, and the risk they can pose to your health. The smaller the particles, the more chance you have of breathing them in, which is where there's greater risk of dangerous particles settling in your lungs and causing damage.
Dust types are categorised into three classes: L Class (Low risk), M Class (Medium risk), and H Class (High risk).
L Class (Low Risk) Dust
L-Class dust is considered some of the least harmful and can be commonly found in the home. Everyday house and soil dust, for example, would fall under ‘L’. Therefore, there is a smaller long-term risk in you breathing this in, though you must still take precautions.
Class L extractors operate at 99% efficiency and therefore work to an occupational exposure limit of 1mg per metre cubed.
Some units in our L Class range come with HEPA filters as standard, which goes above what's required for an L Class classification but makes them even more safe.
M Class (Medium Risk) Dust
M-Class dust is considered medium risk. While this type may not pose the same long-term health risks of class H, it is still highly recommended that you protect against it. Dust class M is common in most industrial workspaces as a result of materials which can generate it. The occupational exposure limit for M Class dust is > 0.05 mg/m³, which means you need a dust extractor that catches 99.9% of the dust.
Wood and quartz-based materials are likely to be the most common cause of the spread of M-class dust. You may experience this dust class while working with any of the following:
Stone
MDF
Cement (standard or tile)
Concrete
Mortar
Repair compound
Paint (oil and latex)
Class M extractors and filters operate at 99.9% efficiency. That means there is an occupational exposure limit of 0.1mg per meter cubed.
M class extractors come fitted with a flow sensor and alarm that advises the user when a dust bag or system is full, or if attention is required. As this dust class is considered more hazardous, it is vital that hardware is kept running at an optimal level at all times.
H Class (High Risk) Dust
H-Class dust is regarded as the most dangerous. This type of dust can travel the furthest into your lungs, and therefore may be considered carcinogenic, or at greatest risk of causing cell necrosis. The occupational exposure limit for H Class dust is < 0.1 mg/m³, which means you need a dust extractor that catches 99.995% of the dust.
Materials likely to create H-class dust and respirable silica may include:
Mortar
Ceramic
Stone
Concrete
Mould spores
Mineral and artificial fibre
Asbestos
Bitumen
Class H filtration and extraction systems operate to 99.995% efficiency and occupational exposure of 0.1mg per metre squared.
H class extractors come fitted with a flow sensor and alarms that advises the user when a dust bag or system is full, or if attention is required. As this dust class is considered hazardous, it is vital that hardware is kept running at an optimal level at all times. H Class filter bags and filters must be used at all times with H Class dust extractors, a safety feature is that you can not operate the extractor with lower levels of protection. Sensors exist for example to ensure the correct filter (H Class) is installed. H Class filter bags are specially designed, the two layer safety filter bag is made from double layered PE material, fulfilling the requirements of dust class H, sealed for safety to prevent contact with contaminents.
Next steps
Now that you understand the different classes of dust it should make it easier to work out what kit you require to protect your health.
If you would like help with your workshop set up, Festool Australia can help on site with a dust extractor demo -> Book a demo
Festool Australia customer service is always happy to help as well if you have further questions -> Customer Service
Festool offer free tool demonstrations, so you can get hands-on with the tools you’re looking at.
Benefit from expert advice and get set up for success with our team of Technical Sales Consultants.
What's the difference between Class L, M and H dust extractors?
Dust Class L, M and H extractors are rated for light, medium and high hazard dust respectively, tested against AS/NZS 60335.2.2:2020. Filtration efficiency increases at each tier: Class L is rated to 99%, Class M to 99.9%, and Class H to 99.995%, with M and H-Class units using true HEPA filtration (H13 or H14) and tested as a complete system including hoses and seals, not just the filter. An L-Class extractor cannot be upgraded to M or H-Class by fitting a better filter; the rating applies to the whole machine.
Do I need an M-Class or H-Class extractor for cutting concrete, brick or stone?
According to WorkSafe Victoria guidance, on-tool dust extraction for crystalline silica work (concrete, brick, stone materials) needs to connect to a Dust Class M or H vacuum. WorkSafe Victoria's exposure standard for respirable crystalline silica is 0.05 mg/m³ as an 8-hour time-weighted average, and concrete-based products typically contain 20 to 30% crystalline silica. Festool CT-Class M and H dust extractors are designed for direct on-tool connection across the relevant product range.
How much crystalline silica is in different stone materials?
Crystalline silica content varies significantly by material, which WorkSafe Victoria notes should inform vacuum selection: quartzite at 70 to 95%, sandstone at 70 to 90%, granite at 25 to 60%, porcelain at 14 to 18%, and marble at less than 5%. Where on-tool extraction is used on stone, WorkSafe Victoria recommends an H-Class vacuum over M-Class where reasonably practicable, given the higher silica content typical of many stone materials.
Is engineered stone banned in Victoria, and what extraction is required for permitted work?
From 1 July 2024, the manufacture, supply, processing or installation of engineered stone benchtops, panels and slabs was banned in Victoria, with limited exceptions including removal, repair or modification of already-installed benchtops and panels, disposal, and research or sampling work. For permitted on-tool extraction work on engineered stone under these exceptions, WorkSafe Victoria specifies the system must be commercially available and connected to a Dust Class H vacuum. This is a Victorian regulation; check current requirements in your own state or territory, as engineered stone rules differ across Australia.
What dust class extractor is recommended for wood dust and MDF?
WorkSafe Victoria's minimum recommendation for smaller portable tools or plant using on-tool extraction with wood dust, including MDF, is a Dust Class M vacuum. The relevant exposure standards are 1 mg/m³ as an 8-hour time-weighted average for hardwood dust and 5 mg/m³ for softwood dust, and MDF is made primarily from softwood fibres. Festool CT-Class M extractors pair directly with sanders and routers for on-tool wood dust capture.
What dust class is needed for plaster and gypsum-based materials?
Plaster materials are primarily gypsum-based, which has a workplace exposure standard of 10 mg/m³ and low inherent toxicity. WorkSafe Victoria notes that where crystalline silica content is checked against the relevant safety data sheet and found to be negligible (often cited as less than 0.1% by weight), a minimum of a Class L vacuum is sufficient. Always confirm the silica content for the specific plaster product in use before selecting extraction equipment.
What safety features distinguish M and H-Class extractors from standard vacuums?
M and H-Class machines include features specifically required for handling medium and high hazard dust: safe removal of dust collection bags without operator exposure, an alarm that triggers when airflow drops below 20 metres per second, and mechanisms that prevent accidental release of captured hazardous dust when the unit isn't in use. These features, combined with HEPA filtration tested to AS/NZS 60335.2.2:2020, are what separate M and H-Class extraction from a standard workshop vacuum.