Frequently asked questions on silica

Crystalline silica is the crystalline form of silicon dioxide and is a naturally occurring mineral that forms a major component of most rocks, soil, sand and clay. It is found in natural stones like granite and sandstone and is used to create manufactured products like bricks, pavers, concrete and tiles. Crystalline silica particles that are less than 10 µm in diameter are known as respirable crystalline silica (RCS). RCS is invisible under normal lighting or with the naked eye and stays airborne for long periods of time. 

A person is exposed to RCS whenever the RCS is airborne and the person can breathe it in. When airborne, workers can breathe RCS particles deep into their lungs where they can lead to a range of respiratory diseases, including:

• silicosis
• progressive massive fibrosis
• chronic obstructive pulmonary disease
• chronic bronchitis
• lung cancer

RCS 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.

Workers must not be exposed to respirable crystalline silica levels above the exposure standard of 0.05 mg/m³ for a standard eight-hour shift. A full list of workplace exposure standards (WES) for air contaminants is available from Safe Work Australia's website. 

The processing of a CSS is defined as:

• the use of power tools or mechanical plant to carry out an activity involving the crushing, cutting, grinding, trimming, sanding, abrasive polishing or drilling of a CSS
• the use of roadheaders involving material that is a CSS
• quarrying involving material that is a CSS
• mechanical screening involving material that is a CSS
• tunnelling involving material that is a CSS, or
• a process that exposes, or is reasonably likely to expose, a person to RCS during manufacture or handling of a CSS (for example cleaning and maintenance processes such as sweeping that may disturb settled RCS). 

The processing of a CSS is defined as 'high risk' as the processing is likely to result in a risk to the health of a person at the workplace. 

Choose wet cutting or grinding systems or systems with engineering controls such as local exhaust ventilation (LEV) fitted to the equipment to reduce airborne RCS. Using wet systems and LEV together further reduces airborne RCS.

If a business or PCBU is carrying out a processing of a CSS that is high risk, you must complete a silica risk control plan before commencing any processing. Wearing a respiratory protective equipment and having administrative controls are still needed even if other control measures are used.

No. Facial hair or stubble along the seal of the respirator reduces the effectiveness of the respirator, and as a result the wearer may be exposed to RCS during their work activities. A fitted respirator requires fit testing to check that it will protect the user. For more information see Respiratory protective equipment - Fit testing requirements.

Workers are responsible to complete a fit check to ensure a fit tested respirator is properly positioned on the face and there is a good seal between the respirator and face. For respiratory protective equipment to be effective, workers who are required to wear tight- fitting respirators must be clean shaven. 

Yes. For engineered stone, r. 184A of the Work Health and Safety (General) Regulations 2022 prohibits cutting, grinding or abrasive polishing unless there is an integrated water control or on-tool dust extraction, or if these are not practicable, local exhaust ventilation. For other silica containing material, uncontrolled dry cutting (ie dry cutting without on-tool extraction or local exhaust ventilation) is non-compliant under s. 19 of the Work Health and Safety Act 2020, and WorkSafe inspectors will take enforcement action where this practice is identified.

Yes, as dry cutting with on tool extraction can still produce significant quantities of RCS (exceeding the workplace exposure standard), the operator and others in the work area all need to wear suitable respirators.

Yes - if slurry is allowed to dry out and dust is generated, people can be exposed to airborne RCS.  Slurry can be managed through the use of on-tool attachments to remove the slurry as it is being produced or by cleaning the slurry whilst wet. 

If any processing of CSS is assessed as high risk, the PCBU must provide health monitoring for all workers carrying out the processing of a CSS that is high risk. Further information can be found in Working with crystalline silica substances: Guide and the health monitoring guides and forms. 

In most cases health monitoring will need to be provided for workers working in the stone fabrication industry, even if standard controls such as wet cutting and respirators are in place. This is because even low exposure to RCS presents a risk.

Examples of work activities that can generate respirable crystalline silica dust particles include:

• excavation, earth moving and drilling plant operations
• clay, sand and stone processing machine operations
• cutting and laying pavers and surfacing
• road construction and tunnelling
• construction, building and demolition involving a CSS
• brick, concrete or stone cutting
• abrasive blasting (blasting agent must not contain greater than 1 per cent of crystalline silica)
• foundry casting
• angle grinding, jack hammering and chiselling of concrete or masonry
• hydraulic fracturing of gas and oil wells
• pottery
• crushing, loading, hauling and dumping of rock, or muck from tunnelling, and
• clean up activities such as sweeping or pressurised air blowing of dust containing crystalline silica.

Air monitoring is important to help you understand the level of risk and whether or not your current controls are adequate. In undertaking any processing of a CSS, you must have regard to the results of any previous air monitoring that has been conducted at the workplace that are relevant to the specific processing of the CSS that are subject of the assessment. 

If previous air monitoring results are not available, personal exposure data obtained from other sources can be used to assess the likely airborne concentration of RCS. This may include exposure data obtained from:

• the manufacturer of the control or tool used
• an industry association
• a certified occupational hygienist

Air monitoring should be conducted by a competent person such as a certified occupational hygienist. The monitoring strategy should be determined by the competent person to ensure that important factors, such as assessment of different work roles, sampling to account for seasonal or other work rate variability and sample size are factored in. Air monitoring that has not been conducted by a competent person is of limited or no use.

Note: Best practice is to use a certified occupational hygienist. However, there may be circumstances where a certified occupational hygienist is not available. Where a certified occupational hygienist is not available, a person with knowledge and experience in occupational hygiene can be used instead.