Silica dust hazards and solutions

A recent spike in the disease is reported to have occurred in some of the workers involved in stone benchtop manufacture, where dry cutting, grinding or polishing of engineered stone-based products can generate high levels of the dust. As a result, the use of engineered stone benchtops panels and slabs has been banned in Australia, except for maintenance, repairs, minor modifications, removal and disposal of engineered stone that was installed prior to the ban. 

Which materials contain crystalline silica?

Crystalline silica is commonly present as quartz in rocks, sand and soil, so products containing any of these materials are likely to contain crystalline silica. Engineered stone generally contains a higher proportion of crystalline silica – typically over 90% – than other construction materials. To find out if a material contains crystalline silica check the product label and Safety Data Sheet (if available) or ask the manufacturer or supplier of the product.

How are workers exposed to respirable crystalline silica?

Occupational exposures can occur where crystalline silica dust is generated and inhaled from materials such as sand, concrete, bricks, tiles, sandstone and other stone.

In Australia, there is a mandatory Workplace Exposure Standard (WES) set at 0.05 mg/m3.  This is the airborne concentration of respirable crystalline silica above which workers must not be exposed at work.

How to protect workers

If you or your workers work with products that contain crystalline silica, it is vital to seek and take note of the safety recommendations of the manufacturer of the product. It is extremely important to be aware of the potential for exposure to airborne dust and what to do to ensure workers are adequately protected.

Exposure to hazardous levels of dust can be reduced considerably by avoiding processes that generate airborne dust during cutting, grinding, crushing, drilling, or sweeping materials that contain crystalline silica.

Where possible, eliminate tasks that generate respirable silica dust. If elimination is not reasonably practicable, one or more of the following three methods will need to be used to control the dust:

• An effective on-tool water suppression system 
• An effective on-tool extraction with high efficiency dust capture system 
• Effective local exhaust ventilation.

Additional control measures include:

• Well-maintained and appropriate respiratory protective equipment (RPE). It is important to choose the right RPE for the job and to ensure it is fitted properly on the worker. A half-face or full-face cartridge respirator rated at P1 or P2 efficiency can be more effective than disposable masks. 
• Provide the necessary instruction and training in correct fitting, use and maintenance of respirators 
• Follow instructions and controls outlined in safe work method statements (SWMS), safety data sheets and product labels 
• Avoid dry sweeping and compressed air as this will push the dust into the air. Use a high efficiency dust capture vacuum cleaner and/or wet wiping to collect surface dust  
• Don’t take dusty clothes home – where possible remove and clean your clothes at the workplace.

Some of these methods are mandatory, so check the website of your local State or Territory workplace health and safety authority to find out the requirements that apply.