Dust Types and Classes

Dust Types and Classes

When working in a dusty environment and especially when handling materials that generate large quantities of dust, your main priority should be protecting your health!


When working in a dusty environment with materials that generate large quantities of dust, your main priority needs to be protecting your health! 

Avoiding as much dust as possible is a good general rule. 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; 1) the size of the dust particles, 2) the quantity, and 3) 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, it is imperative that you keep the air clean when handling mineral dust that invariably contains quartziferous substances and always work with a certified and approved dust extractor or safety extractor.

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 (low risk) dust includes simple house dust and materials such as soil. The occupational exposure limit for L Class dust is >1 mg/m3, which means you need a dust extractor that catches 99% of the dust.

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 (medium risk) dust includes wood dust, dust from repair compound, filler and clear coats, dust from cement, concrete and tile cement, quartziferous materials such as sand and pebbles, and even paints such as latex and oil paints. 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.

For dust generated by working with concrete or materials containing Crystalline Silica, the CTM 36 HD Autoclean is recommended.

Read more about M Class dust here.


H Class (High Risk) Dust

H Class (high risk) dust includes dust containing carcinogenic or pathogenic particles as well as mould spores, asbestos, mineral fibres, bitumen and artificial mineral fibres such as glass wool. 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.


Free Dust Safety Resources For You 

Take the Dust Safety quiz

Download the complete 'Working With Hazardous Dust' brochure

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Respirable Crystalline Silica Dust


What is Respirable Crystalline Silica dust? It's a natural mineral found in construction materials such as concrete, bricks, tiles, mortar and engineered stone.

The amount of crystalline silica in products can vary. Examples include:

  • Brick 5-15%
  • Concrete <30%
  • Ceramic tiles 5-45%
  • Reconstituted stone 80%

Silica dust is harmful when inhaled into your lungs. It is 100 times smaller than a grain of sand, so you can be breathing it in without knowing. If you’re not sure if a product contains crystalline silica, check the safety data sheet (SDS).

Exposure to silica dust can lead to the development of lung cancer, silicosis (an irreversible scarring and stiffening of the lungs), kidney disease and chronic obstructive pulmonary disease. It is estimated that 230 people develop lung cancer each year as a result of past exposure to silica dust at work. Not all exposed workers will develop cancer; cancer risk increases with long term or repeated high level exposure.

Today, all States and Territories in Australia have work health and safety laws that explain duty of care for employers and workers’ responsibilities:

Western Australia – Visit website 

Queensland – Visit website 

New South Wales – Visit website 

Victoria & Tasmania – Visit website  

Australian Capital Territory – Visit website  

Northern Territory – Visit website 

South Australia – Visit website   

The Australian exposure standard for airborne crystalline silica is 0.1mg/m3 over an 8-hour day. This limit is based on preventing silicosis and lung cancer.


On-Tool Dust Extraction

A dust extractor is very important when it comes to dust safety, but the tools you use to work the material surface can have a big impact on the level of dust you're exposed to as well. 

On-Tool Dust Extraction is a type of Local Exhaust Ventilation (LEV) which is fitted directly onto the tool. There are two main forms of this:

  • One involves a LEV ‘system’ consisting of several individual parts – the tool, captor hood, dust extraction unit and tubing.
  • The other is 'integrated dust extraction devices' which are available for some hand-held tools. These self-contained units are fitted directly onto the tool where they automatically filter and collect dust. You should extract dust from the unit using a dust extractor.

Festool power tools are specifically designed to capture superior amounts of dust through either the tool features or integrated dust extraction devices. 


Filter Bags

International standard IEC 60 335-2-69 requires M Class and H Class dust extractors to use filter or disposal bags because dust must not be spread when disposing of it. Only the use of filter bags or disposal bags can guarantee this.

Also, using a dust extractor without a filter bag or disposal bag means it takes much longer to empty and clean the collection container. If you calculate the cost of this additional time at the relevant hourly rate, the price of a filter bag or disposal bag gives you the most economical solution.

A filter bag is usually made of a special cloth or paper material and is completely sealed, whereas a disposal bag is manufactured from a plastic material similar to a classic garbage bag and is open at the top and placed into the container so that the edge of the bag protrudes over the edge of the container slightly and can be folded over.

Disposal bags were developed specially for extractors with an automatic filter cleaning system. Accordingly, only one type of disposal bag can be used in these extractors. Typical applications include work that generates large quantities of fine dust, such as sanding plasterboard filler.

For every Festool mobile dust extractor, there is a matching filter bag designed for the relevant dust class and material to be extracted:

  • Selfclean filter bag - For disposable use with all kinds of dust. Prevents dust from caking on the sides through its self cleaning effect, and is sealed before disposal for maximum health protection.
  • Longlife filter bags - Reusable due to its high strength, three ply non woven polyester material. Ideal for large quantities of L Class dust. Easy to empty by opening the sealing strip.
  • Waste bag - Perfect for dust extractors with AUTOCLEAN, e.g. for use with the PLANEX long reach sander or for extraction of coarse waste and chips.
  • Two layer safety filter bag - A requirement for dust of class H. Extra safe, with an additional waste bag which encloses the non woven filter bag.


Other Resources

For more information on dust safety, dust extraction and the Festool range, you can contact us directly. We also have a range of articles available in our Dust Safety hub.