Silica

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Silica is a common naturally occurring mineral. Inhaling respirable crystalline silica dust can lead to serious lung conditions such as silicosis.

What is silica and where is it found? 

Silica is a common naturally occurring mineral, also known as silicon dioxide. One common type of crystalline silica is quartz. Silica can be found in different forms, broadly divided into crystalline and non-crystalline (amorphous).

Crystalline silica is a major constituent of many types of sand and rocks (e.g., granite, slate, sandstone). It is a component of concrete, some bricks, natural stone products, and engineered stone products. When crystalline silica is subjected to high-speed abrasive processes, such as cutting, grinding and polishing, it gives off very fine particles of crystalline silica dust. These very fine particles can be inhaled deep into the lung and are referred to as respirable. This presents a serious health hazard. Consequently, this hazard can be found in industries such as construction, masonry, mining, and foundries. This information focuses on respirable crystalline silica, which is the most hazardous form. 

Respirable crystalline silica is classified as a hazardous chemical according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) and has a workplace exposure standard. The WHS Regulations include specific requirements for a PCBU to manage the risks associated with hazardous chemicals, including air monitoring and health monitoring.

What are the risks? 

Silica dust is a significant health hazard for workers. Very small particles of silica dust cannot be seen under normal lighting or with the naked eye and stay airborne for long periods of time. When airborne, workers can easily inhale the small silica dust particles deep into their lungs where it can lead to a range of respiratory diseases, including:

  • silicosis (an incurable lung disease, with inflammation and scarring of the lungs, causing shortness of breath, coughing, fatigue and other symptoms). Silicosis can develop either quickly or slowly depending on exposure levels. It is a potentially fatal condition).
  • progressive massive fibrosis
  • chronic obstructive pulmonary disease
  • chronic bronchitis
  • lung cancer.

Silica dust also increases the risk of developing chronic kidney disease, autoimmune disorders (such as scleroderma and systemic lupus erythematosus) and other adverse health effects, including an increased risk of activating latent tuberculosis, eye irritation and eye damage.

What tasks can lead to high crystalline silica exposure? 

  • Jack-hammering concrete
  • Dry sanding of concrete
  • Dry cutting, grinding or polishing of brick, concrete, stone, or engineered stone
  • Abrasive blasting where the blasting agent or the surface being blasted (e.g. brick, concrete) contains significant silica content;
  • Earthworks
  • Rock crushing
  • Mineral sample milling
  • Roadworks
  • Other tasks where dust is generated from a material with high crystalline silica content.

Crystalline silica particles that have just been fractured or abraded are more hazardous (e.g. crushing or cutting processes). 

Work health and safety duties

Workers and management must work together to reduce risks. A safe place of work benefits everyone.

For businesses or PCBUs

As a business, you must manage your workers’ exposure to respirable crystalline silica dust and put measures in place to keep workers safe and healthy. In addition to your usual responsibilities and duties under WHS there are specific laws that require you to protect workers exposure to silica.

Workplace exposure standard

A PCBU must ensure that no person at the workplace is exposed to respirable crystalline silica, at a concentration above the workplace exposure standard. The workplace exposure standard for respirable crystalline silica is an eight hour time weighted average (TWA) of 0.05 milligrams per cubic metre (mg/m3). More information can be found in the Safe Work Australia (SWA) Guidance on interpretation of Workplace exposure standards for airborne contaminants.

Air monitoring

Air monitoring involves measuring the level of respirable crystalline silica in the breathing zone of workers by using a personal sampler during their usual shift activities (including routine breaks). Air monitoring is important to:

  • check the effectiveness of control measures
  • monitor the workplace atmosphere to ensure the workplace exposure standard is not being exceeded
  • help choose the right level of respiratory protection
  • inform health-monitoring requirements.

Air monitoring results must be kept for 30 years after the record is made and be readily available to those who may be exposed to the substance or mixture in the workplace.

According to work health and safety laws, you must carry out air monitoring if:

  • there’s uncertainty whether the airborne concentration exceeds the exposure standard, or
  • monitoring is necessary to determine whether there is a risk to health.

Some businesses and industries, such as the stone-benchtop industry have specific air monitoring requirements that are outlined in the Managing the risks of respirable crystalline silica from engineered stone in the workplace: Code of practice.

Health monitoring

Health monitoring of a worker means monitoring the worker to identify changes in their health because of exposure to certain substances. It involves collecting data to measure exposure or evaluate its effects and determine whether the absorbed dose is within safe levels.

A PCBU must organise and pay for health monitoring if there is a risk to the health of their workers because of exposure to silica dust at the workplace. Health monitoring identifies any changes to the health of workers resulting from exposure to respirable crystalline silica (RCS).

Under WHS Regulations, the minimum requirements for health monitoring for crystalline silica through exposure to silica dust are:

  • collection of demographics, medical and occupational history
  • records of personal exposure
  • standardised respiratory questionnaire
  • standardised respiratory function tests, for example, FEV1 (forced expiratory volume in one second), FVC (forced vital capacity) and FEV1/FVC (respiratory ratio, or Tiffeneau index)
  • low dose high resolution computed tomography of the chest at less than 1 millisievert (mSv) equivalent dose for the entire study. The study must image the whole of each lung on inspiration at 1.5 mm slice thickness or less, without an interslice gap, and must include expiratory imaging. The images must be of adequate quality to detect subtle abnormalities, including ground glass opacities and small nodules.

The registered medical practitioner who prepares the health monitoring report must give the regulator a copy if the report contains monitoring results consistent with exposure to silica.

More information on health monitoring of workers for exposure to crystalline silica can be found in the Health monitoring guide for registered medical practitioners: Silica (respirable crystalline)

Health monitoring records must be kept confidential and for at least 30 years after the record is made, even if the worker no longer works at the workplace.

More information about health monitoring reports can be found in the Health monitoring duties for persons conducting a business or undertaking: Guide.

For workers

Take care of your own health and safety

As a worker, you must take reasonable care for your own health and safety and not adversely affect the health and safety of others. You must comply with reasonable instructions and cooperate with reasonable health and safety policies or procedures.

Wear and correctly use personal protective equipment

You must wear and correctly use personal protective equipment if it is provided. Ask for a replacement if it is damaged or needs to be cleaned.

 

Managing the risk

Workers and management can work together to reduce exposure to crystalline silica dust. Businesses must manage risks to workers’ health and safety and workers must also take steps to protect themselves. A safe place of work benefits everyone.

To meet the workplace exposure standard, you should follow a risk management process to identify risks and the measures you can use in your workplace to minimise the amount of dust workers are exposed to.

If you are working in the stone benchtop industry, you must comply with the Managing the risks of respirable crystalline silica from engineered stone in the workplace: Code of practice. The code provides detailed, practical guidance on how to manage the risks associated with respirable crystalline silica.

Step 1: Identify hazards

Silica can be identified by considering the types of materials used in the task. More information is available in material safety data sheets where these are available (eg for abrasive blasting agents) and from material suppliers.

The first step is to identify respirable dust hazards. The following examples give an indication of the varying levels of crystalline silica in different products:

  • engineered stone: up to 95%
  • sandstone: 70–90%
  • concrete, mortar: 25–70%
  • brick: up to 30%
  • granite: 20–45%
  • fibre cement sheets: 10–30%
  • demolition dust: 3–4%
  • marble: 2%

You can check safety data sheets and other information from suppliers to find out whether products contain crystalline silica.

Identify where and how dust from these products is being released at your place of work. This may be achieved by:

  • conducting a walk-through assessment of the workplace
  • observing the work and talking to workers and/or HSRs about how work is carried out
  • inspecting the plant and equipment that is used as part of the fabrication and other relevant processes – for example, hand-held tools may generate more silica dust than automated machinery
  • undertaking air monitoring at the workplace
  • inspecting workplace surfaces for build-up of settled dust, and
  • reading product labels, safety data sheets and manufacturers’ instruction manuals.

Step 2: Assess the risk

A risk assessment involves considering what could happen if a worker is exposed to a hazard and the likelihood of it happening. Exposure to silica dust can adversely affect a worker’s health, including developing silicosis, progressive massive fibrosis, chronic obstructive pulmonary disease, chronic bronchitis, and lung cancer.

If you have identified silica, assess the risks by carrying out a risk assessment. The risk of silica exposure from the task is assessed by examining the work processes involving crystalline silica. The assessment must consider the dust exposure that could occur. Having dust levels monitored is the most accurate way to assess the risk, however in some cases (e.g. where there are visible clouds of dust from high silica materials, such as during dry concrete cutting) the risk may be clear without monitoring.  It should be noted that very fine particles may be difficult to see in air, and monitoring is required to assess the risk from such particles.

Silica dust control plan

A silica dust control plan is a practical tool for a PCBU that is informed by a risk assessment. It can help a PCBU identify all potential tasks that may result in exposure, or possible exposure, to silica dust and the control measures to eliminate or minimise that exposure. A template for a silica dust control plan is provided in the code of practice.

Step 3: Control risks

The WHS Regulations require that exposure to silica dust is prevented where practical. If exposure can’t be prevented, the risk must be reduced as far as reasonably practicable. Examples of controls for crystalline silica include:

  • choosing materials (eg abrasive blasting agents) that are silica free or have the lowest silica content
  • designing buildings with recesses for services to reduce the amount of chasing required
  • providing vehicles with enclosed cabs fitted with high efficiency air filters, for dusty earthworks or mining 
  • using wet work methods to reduce dust (e.g. wet cutting or polishing, water sprays during earthworks)
  • using water spray or rubber curtains around conveyor transfer points
  • using local extraction ventilation, either fixed or on-tool (e.g. for mixing, crushing, milling, drilling or chasing)
  • shadow vacuuming (e.g. during drilling)
  • vacuum clean-up rather than sweeping
  • not blowing dust with compressed air
  • in addition to other controls, PPE such as an appropriate respirator (selected in accordance with Australian/New Zealand Standard AS/NZS 1715 Selection use and maintenance of respiratory protective equipment) may be required, depending on the task and the effectiveness of the other controls

Further guidance on the risk management process and the hierarchy of control measures is available in the How to manage work health and safety risks: Code of practice.

Step 4: Review risk controls

You should regularly review your control measures to make sure they remain effective for managing your workplace risks.

For example, a PCBU should conduct daily start up checks to ensure that:

  • machine and water mist guards and LEV are fitted correctly and are working effectively
  • LEV filters are clean and replaced according to the manufacturer’s instructions
  • there is an adequate water supply for water suppression
  • all respiratory protective equipment (RPE) is in good, working condition and fit checked.

A PCBU should routinely monitor the workplace for signs of visible dust on work surfaces or clothing as that may be an indication that some controls are not working effectively.

Further guidance on the risk management process is available in the How to manage work health and safety risks: Code of practice.

For benchtop industry 

Dry cutting, trimming, drilling, sanding, grinding or polishing engineered stone without effective controls generates very high levels of silica dust. A PCBU must not direct or allow workers to undertake uncontrolled dry cutting or processing of engineered stone. This will expose workers and others to levels of silica dust that would be expected to exceed the workplace exposure standard and is a serious risk to health.

Guidance

Further guidance on how to effectively manage risks associated with working with engineered stone and, subsequently, minimise the incidence of respirable crystalline silica related diseases, such as silicosis is available in the Managing the risks of  respirable crystalline silica  from engineered stone in the workplace: Code of practice.

From 1 July 2024 the use of engineered stone will be banned in Western Australia. You can read about the announcement below.

The National Work Health and Safety Ministers met on 22 March 2024 to decide on further details of the ban on engineered stone. The following decisions were made: 

  • The use, supply and manufacture of engineered stone slabs, panels and benchtops will be banned in Western Australia from 1 July 2024. but a transition period will last until 31 December 2024. 
  • The pre-existing contracts entered into before 1 January 2024 for engineered stone may be honoured during the transition period. 

For further details

Western Australia joins other Australian jurisdictions in prohibiting the use of engineered stone. More information on the National approach can be found here:

Note: Western Australia will join the rest of the country in banning the use of engineered stone in workplaces due to the risk to workers of silicosis. The ban will take effect from 1 July 2024. 

Further Information

 

WorkSafe

Standards and compliance

Other WorkSafe publications

Codes of practice and guidance materials

Other publications 

Safe Work Australia

SafeWork New South Wales

Australian Institute of Occupational Hygienists

International

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