Stonemasons: Preventing crystalline silica exposure

Identifying hazards and controlling the risks of exposure to dust containing crystalline silica in the stonemasonry industry.

What is crystalline silica

Crystalline silica is a natural mineral found in stone products. The table below lists the common stone products and their typical crystalline silica content.

  • engineered stone: 40% to 95%
  • sandstone: 70% to 90%
  • granite: 25% to 60%
  • slate: 20% to 40%
  • porcelain: 14% to 18%
  • marble: Less than 5%

Engineered stone is also known as reconstituted, artificial or manufactured stone.

Under the Occupational Health and Safety Regulations 2017 (OHS Regulations) engineered stone is defined as a manufactured composite stone material that contains resins and 40% or more crystalline silica.

High levels of crystalline silica may also be found in some natural stone products. To find out how much crystalline silica is in a product, check the safety data sheet (SDS) or other information from the supplier.

Working with different silica-containing materials

Under the OHS Regulations, different duties may apply depending on which silica-containing material you are working with.

For example, specific risk control measures must be used when working with engineered stone. When working with other materials such as natural stone, these controls may not be prescribed under the OHS Regulations, however in most cases they will be reasonably practicable measures to control the risk associated with working with the silica-containing materials.

This guidance includes information about using risk control measures for working with engineered stone as well as other crystalline silica-containing materials.

Stonemasons are exposed to crystalline silica dust

Tasks like cutting, grinding or abrasively polishing stone products release respirable crystalline silica dust – dust particles small enough to breathe into your lungs. This dust may not be visible.

Stonemasons will be exposed to crystalline silica dust, especially when using power tools to cut, grind or polish stone products. In particular, people working in benchtop fabrication are at a higher risk, because they regularly work with engineered stone, which has a very high crystalline silica content. Any uncontrolled processing of engineered stone that generates crystalline silica dust, including cutting, grinding or polishing with power tools or other mechanical plant, is not permitted in Victoria.

Health risks

Silica dust can be harmful when inhaled into the lungs over a long period of time at low to moderate levels, or short periods at high levels.

When respirable crystalline silica dust is inhaled it can cause silicosis, which is a scarring of the lungs. Silicosis is a serious and incurable disease, with symptoms including shortness of breath, coughing, fatigue and weight loss. In severe cases, the damage caused to the lungs by silicosis can require a lung transplant or may even lead to death.

In recent years, identified cases of silicosis have been increasing, in particular ‘accelerated’ silicosis caused by short periods of high levels of exposure.

Breathing in silica dust can also cause other serious diseases, such as:

  • lung cancer
  • kidney disease
  • autoimmune diseases, such as scleroderma

Exposure standard

Safe Work Australia publishes exposure standards for airborne contaminants in the workplace.

The workplace exposure standard for crystalline silica dust (listed under Quartz (respirable dust)) is 0.05 mg/m3 as a time-weighted average) airborne concentration over 8 hours.

An 8-hour time-weighted average (TWA) exposure standard is the average airborne concentration of a particular substance permitted over an 8-hour working day, 5-day working week. For people working extended shifts, the TWA will need to be adjusted.

The workplace exposure standard for respirable crystalline silica is based on the levels found in a person’s breathing zone, outside of any respiratory protective equipment that may be in use.

Employers are required to ensure employee exposure does not exceed this standard.

WorkSafe Victoria recommends that employees are not exposed to levels above 0.02 mg/m3 as a TWA. This is a precautionary measure to minimise the risk of silica-related disease such as silicosis and lung cancer.

Engineered stone processes

An engineered stone process is a process involving engineered stone at a workplace that generates crystalline silica dust, including cutting, grinding or abrasive polishing of engineered stone.

By law, employers and self-employed persons must ensure specific risk controls are used when engineered stone processes are undertaken in their workplace. For more information see Required controls for undertaking engineered stone processes.

Engineered stone control plan must be prepared

An employer or a self-employed person engaged in undertaking an engineered stone process must prepare an engineered stone control plan (ESCP) before commencing that work.

The work must be performed in accordance with the ESCP. If the work is not performed in accordance with the ESCP, the employer or self-employed person must stop that work immediately or as soon as it is safe to do so. Work must not resume until the ESCP is complied with or reviewed and, if necessary, revised in accordance with the OHS Regulations.

Transition to engineered stone licences

From 15 November 2022, employers or self-employed persons engaged in undertaking an engineered stone process at the workplace for which they are responsible must hold an engineered stone licence. An employer or self-employed person who requires an engineered stone licence must apply for the licence as soon as reasonably practicable after the regulations commence on 15 November 2021.

Engineered stone licence holders will be required to prepare an ESCP before undertaking work involving an engineered stone process.

For the period prior to 15 November 2022 employers and self-employed persons undertaking an engineered stone process are not required to hold an engineered stone licence while their licence application is being processed, but must prepare an ESCP in accordance with the OHS Regulations before any work involving an engineered stone process is undertaken.

Controlling the risk of exposure

Employers must control the risks associated with exposure to crystalline silica by applying the hierarchy of control in Part 4.1 (Hazardous substances) of the OHS Regulations.

An employer must, so far as is reasonably practicable, eliminate the risks associated with exposure to crystalline silica dust in their workplace (for example by using non silica-containing products).

If it is not reasonably practicable to eliminate a risks associated with crystalline silica, the employer must reduce the risk so far as is reasonably practicable by:

  • substitution (for example instead of using engineered stone, which can be up to 95% silica, use natural stone, which can have a much lower silica content)
  • isolation (for example using automated wet machines)
  • engineering controls (see below) or
  • a combination of any of the above risk control measures

If the risks from exposure still remains after the above risk control measures have been implemented, administrative controls (such as rotation during shifts between high and low exposure tasks) must be used to reduce the risk so far as is reasonably practicable.

If a risk remains, an employer must provide appropriate personal protective equipment, such as respiratory protective equipment (RPE).

It is most likely that more than one control will be needed to control the risk adequately.

When engineered stone processes are undertaken, specific risk controls must be used in addition to the requirement to apply the hierarchy of control in Part 4.1 of the OHS Regulations - see Required controls when undertaking engineered stone processes.

Consultation

Employers must consult, so far as is reasonably practicable, with their employees (and independent contractors) on certain matters related to health and safety that directly affect or are likely to directly affect them. For example, when they are identifying or assessing hazards or making decisions about measures to control risks associated with crystalline silica exposure. If employees are represented by a health and safety representative (HSR), the consultation must involve that HSR (with or without the involvement of the employees directly).

Required controls when undertaking engineered stone processes

When power tools are used

The uncontrolled dry cutting of engineered stone is not permitted in Victoria.

An employer or self-employed person must ensure that when a power tool or other form of mechanical plant is used for an engineered stone process, it is used with:

  • an integrated water delivery system that meets the requirements set out below, or      
  • an on tool dust extraction system that meets the requirements set out below, or
  • if these controls are not reasonably practicable, local exhaust ventilation (LEV)

An integrated water delivery system must:

  • deliver a continuous supply of water to the point of contact with the stone while the power tool is in use, and
  • if the system uses recycled or recirculated water, adequately treat that water.

An on tool dust extraction system must:

  • be commercially available, and
  • be connected to a Dust Class H Vacuum or another system that captures any dust generated by the power tool.

Dust Class H vacuum means a vacuum that complies with the Class H requirements in AZ/NZS 60335.2.69:2017 Household and similar electrical appliances—Safety—Part 2.69: Particular requirements for wet and dry vacuum cleaners, including power brush, for commercial use or its equivalent.

Local exhaust ventilation means an engineering control that captures the emission of an airborne contaminant at its source and transports it to a safe emission point, filter or scrubber.

Where an integrated water delivery system, on tool dust extraction system or LEV system is required, employers and self-employed persons must ensure those systems are designed and installed to, so far as is reasonably practicable, eliminate or reduce the risk of exposure to crystalline silica dust.

Employers and self-employed persons must also ensure the systems are used and maintained in a manner that, so far as is reasonably practicable, eliminates or reduces the risk of exposure.

For more guidance on these controls see Use of engineering controls to minimise exposure to crystalline silica dust.

Provide respiratory protective equipment

Employers must provide an employee who undertakes an engineered stone process with RPE that:

  • is designed to protect the wearer from the inhalation of airborne contaminants and
  • complies with AS/NZS 1716 – Respiratory protective devices, or requirements equivalent to those of the standard

The employer must also ensure the employee uses the RPE.

For more guidance on the use of RPE see Respiratory protective equipment (RPE).

Provide information, instruction and training

Employers must provide information, instruction and training to employees who use power tools or other forms of mechanical plant to undertake engineered stone processes, including on:

  • the use of the power tool or mechanical plant and any control measures implemented to reduce the risk of exposure
  • the use, fit, maintenance and storage of RPE provided

For more guidance see Information, instruction and training.

Prohibition on cleaning with compressed air and gases

An employer or self-employed person must ensure compressed air and compressed gases are never used to clean:

  • a work area where an engineered stone process has been undertaken, or
  • clothing a person wore in a work area where an engineered stone process was undertaken,

unless the use does not result in a concentration of respirable crystalline silica that exceeds the exposure standard.

For more guidance see Reducing dust during clean up and housekeeping.

Use of engineering controls to minimise exposure to crystalline silica dust

On tool water suppression

On tool water suppression is one of the most effective ways to reduce exposure to crystalline silica dust.

Water suppression uses water at the point of dust generation to dampen down or suppress dust before it is released into the air. WorkSafe views this control as reasonably practicable in most situations.

Water recycled onsite for use in water suppression needs to be effectively filtered to remove crystalline silica particles and prevent contaminated water continually passing through the system with an increasing crystalline silica concentration.

Water that is recycled needs to be visually assessed to ensure it is clear. If the water has a cloudy or milky appearance this means it is likely to contain a high concentration of crystalline silica, and creates a risk respirable particles will be released into the air.

On tool dust extraction

Another effective way to reduce exposure to crystalline silica dust is to use on tool dust extraction, which removes the dust from the source as it is being produced. It is fitted directly onto the tool, with extraction attached to a high efficiency particulate air (HEPA) filtered Dust Class H vacuum cleaner.

Local exhaust ventilation

LEV systems such as hoods, booths or extraction walls should only be used in combination with on tool water suppression or on tool dust extraction. Where engineered stone processes are undertaken, LEV must only be used if it is not reasonably practicable to use an integrated water delivery system or a commercially available on tool dust extraction system

LEV requires proper design, installation, use and maintenance to ensure dust is effectively captured at the source.

Respiratory protective equipment (RPE)

RPE needs to comply with AS/NZS 1716 – Respiratory protective devices. This is mandatory where engineered stone processes are undertaken and strongly recommended for working with other crystalline silica materials.

Check the product information to make sure RPE is AS/NZS 1716 compliant. If it is not clear, ask the supplier or contact the manufacturer.

RPE needs to have at least a P2 filter and be fit tested for each person to ensure a correct fit. RPE that requires a facial seal, such as half-face respirators, should not be used by people with beards or facial stubble. Where facial hair interferes with the fit of the RPE, a powered air purifying respirator (PAPR) that does not rely on a facial seal needs to be used, such as a PAPR loose fitting helmet.

RPE needs to be selected, used and maintained in accordance with AS/NZS 1715 – Selection, use and maintenance of respiratory protective equipment.

Employers need to provide employees with information, instruction and training in the use, fit and maintenance of RPE, including the system for storage. This is mandatory where engineered stone processes are undertaken – see Required controls when undertaking engineered stone processes.

Reducing dust during installation work

Employers need to eliminate cutting at the installation site to prevent dust from being generated during installation work. Ways to do this include:

  • asking builders to provide a template for pre-cutting the silica-containing materials at the fabrication workshop
  • ensuring installation measurements are correct - using lasers may assist in taking precise measurements for off-site installations
  • asking builders to communicate any installation changes before employees attend the site (eg changes to location or measurements)
  • when modifications are found to be necessary, directing that the slab be taken back to the fabrication workshop rather than undertaking processing at the installation site

If it is not possible to eliminate cutting during site installation, employers must control exposure to respirable crystalline silica using the prescribed control measures listed above (see Required controls when undertaking engineered stone processes).

If an engineered stone process is undertaken at the installation site, an ESCP must be prepared before the work commences (see Engineered stone control plan must be prepared).

Reducing dust during clean up and housekeeping

The work area should be cleaned after each job is completed to ensure there is no build-up of respirable crystalline silica dust on plant, equipment, working surfaces or the floor. RPE needs to be worn during clean-up activities.

Ensure clean-up and housekeeping processes don't generate dust in the air. For example, use a HEPA filtered Dust Class H vacuum, low pressure hosing, mopping, squeegeeing or wet wiping down surfaces. Never use compressed air, dry sweeping or high-pressure water to clean up as this is likely to generate airborne dust.

The use of compressed air and compressed gases is prohibited where engineered stone processes have been undertaken, unless their use does not result in a concentration of respirable crystalline silica that exceeds the exposure standard (see Required controls when undertaking engineered stone processes).

Wet slurry

Wet slurry needs to be managed by capture or containment through floor bunding, grading, grates, curbing and channelling. Wet slurry should not be allowed to dry and become airborne. Slurry capture systems need to be regularly inspected to ensure drains are not clogged and the system is operating effectively.

Personal decontamination

Personal protective equipment such as RPE, aprons and boots need to be cleaned after each use to ensure dust does not accumulate. For example, by using a low pressure hose or wiping down with wet rags. Work clothes should not gather dust if exposure is appropriately controlled during processing work. However, if dust has settled on clothing, the contaminated clothing should be dampened, bagged, and labelled with 'Silica dust hazard'. Contaminated clothing should not be taken home but should either be laundered on site or sent to a commercial laundry. If a commercial laundry is used, the employer or self-employed person needs to determine with the laundry how it wants to receive the clothing.

Managing crystalline silica waste

Employers must control the risk of exposure to crystalline silica dust during waste management and disposal. For example, when wet slurry is collected, or dust captured by an extraction system is ready for disposal, it needs to be contained and handled in a way that minimises the release of dust. Containers of waste contaminated by silica dust must be identified, for example by a label that clearly states 'Silica dust hazard'.

Information, instruction and training

Employers must provide their employees with any necessary information, instruction, training and supervision to enable them to do their work safely. For example, training needs to be provided to employees on:

  • crystalline silica hazards and health risks
  • how to effectively use controls
  • use and maintenance of RPE
  • how to dispose of waste
  • methods for personal decontamination

The structure, content and delivery of the training needs to take into account any special requirements of the employees being trained. For example, information, instruction and training may need to be provided in a language other than English. Refresher training needs to be provided regularly.

Where engineered stone processes are undertaken, specific additional requirements apply for the provision of information, instruction and training (see Required controls when undertaking engineered stone processes).

Employers should provide all applicants applying for employment at a workplace where engineered stone processes are undertaken with information about the health risks associated with exposure to crystalline silica dust and the need for, and details of, measures used to control those risks.

Air monitoring

By law, employers must carry out air (atmospheric) monitoring for crystalline silica dust generated at their workplace where:

  • there is uncertainty about whether the exposure standard is or may be exceeded, or
  • air monitoring is necessary to determine whether there is a risk to health

There is insufficient evidence to show that any single control or combination of controls is guaranteed to keep exposure to respirable crystalline silica below the exposure standard when power tools are used on engineered stone.

Employers need to conduct an ongoing air monitoring program to confirm that the exposure standard for respirable crystalline silica is not being exceeded.

In addition to the ongoing schedule, employers should conduct air monitoring:

  • when there are changes to work practices, the materials being used or the work environment
  • if a health monitoring report for an employee indicates a negative change in health status which may be related to silica exposure
  • if a health and safety representative requests a review of control measures
  • if there are changes to the workplace exposure standard, and previous air monitoring results have indicated levels above the new standard

Air monitoring and the interpretation of results (including comparison with the exposure standard) needs to be undertaken by a person with the requisite skills, knowledge and experience (such as an occupational hygienist). The Australian Institute of Occupational Hygienists (AIOH) represents the occupational hygiene field. A list of service providers with the right experience to conduct air monitoring can be found on the AIOH website.

Results of air monitoring must be provided to the employees who have been, or may have been, exposed and should be made accessible to relevant HSRs. Air monitoring results should also be made available to the medical practitioners who are conducting health monitoring for employees.

Health monitoring

Employers must provide health monitoring if exposure to crystalline silica is likely to have an adverse effect on employees' health.

Due to the high silica content of engineered stone, it will be likely that employers must provide health monitoring to all employees who work in the vicinity of engineered stone processing work. This includes, but is not limited to, employees directly involved in engineered stone processing tasks, as well as other employees such as supervisors, labourers, forklift operators, cleaning and maintenance staff, office and sales staff.

Health monitoring must be undertaken by a registered medical practitioner. It needs to be carried out by a specialist occupational physician or a specialist respiratory and sleep medicine physician. A list of practitioners can be found on the Royal Australasian College of Physicians website at racp.edu.au. Employers should speak to the occupational physician or respiratory and sleep medicine physician to ensure they have experience with silicosis and other silica dust diseases.

Where health monitoring is required, it should be completed when an employee is hired with a new employer (before they start work), regularly while they are in the job and when they finish working for that employer.

When an employee who has been undertaking engineered stone processes ceases employment, it is recommended that their employer provides them with a written statement that sets out:

  • the period during which the employee worked with engineered stone
  • a recommendation that the employee has periodical health assessments, and the types of tests that are relevant