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Managing respirable crystalline silica in bench top fabrication

Engineered and natural stone used for bench tops contains crystalline silica, also called quartz. Cutting, grinding and polishing natural or engineered stone generates respirable crystalline silica, which puts workers' health at risk. Engineered stone bench tops have a very high crystalline silica content, up to 95%.

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Health effects

Inhaling respirable crystalline silica can lead to silicosis, an incurable lung disease that can lead to disability and death. Respirable crystalline silica exposure can also cause lung cancer and chronic obstructive pulmonary disease (COPD), and may contribute to renal cancer.

Silicosis may occur after exposure to respirable crystalline silica over many years, but very high exposures across the short-term can cause it to develop rapidly. This is known as Acute Silicosis.

Signs and symptoms of silicosis may not appear until years after exposure and includes:

  • shortness of breath that may worsen with exertion
  • persistent cough
  • fatigue
  • rapid breathing
  • loss of appetite and weight loss
  • chest pain
  • fever
  • gradual darkening of skin (blue skin).

Silicosis can develop or continue to progress even after exposure to respirable crystalline silica has stopped.

Managing exposure

Identification

Processes that generate respirable crystalline silica during the fabrication of bench tops include cutting, grinding or polishing stone.

Control the risks

Eliminating exposure to respirable crystalline silica is the most effective control measure for managing the risk of work related illness.

Where exposure cannot be eliminated, any exposure to respirable crystalline silica must be minimised so far as is reasonably practicable.

The Stone bench top industry PCBU guide(PDF, 663.78 KB) provides detailed information about managing respirable crystalline silica risks.

Stopping or reducing the dust

Eliminate dry cutting, grinding or polishing stone during fabrication or installation.

Minimise respirable crystalline silica by:

  • planning work to ensure the least amount of cutting, grinding and polishing is needed
  • using routers and water jet cutters instead of powered hand tools to cut stone
  • housekeeping - regularly cleaning daily using methods that include:
    • wet sweeping
    • hosing down with low pressure water/wiping/mopping of surfaces
    • vacuuming up dust and debris containing silica using a H-class vacuum cleaner
  • waste disposal – you can reduce dust associated with waste by:
    • locating bins and skips outdoors where possible
    • using water misting systems to keep waste materials damp where possible.

Note: Uncontrolled dry cutting, grinding or polishing stone is prohibited in Queensland workplaces.

These activities generate levels of respirable crystalline silica dust that even respiratory protective equipment is not able to effectively protect workers from exposure to silica dust.

Controlling the dust

Where elimination or substitution of respirable crystalline silica work processes is not practical, engineering controls such as dust extraction and water suppression must be used in addition to suitable respiratory protection.

Common control options

Water suppression

Water or fine mist suppression can be used to control respirable crystalline silica dust. However, it needs to be used correctly. This means enough water supplied with adequate flow for the whole time that the work is being done.

Water suppressed equipment includes wet cutting bridge saws, routers and water fed grinders or polishers. Tools must be designed to be used with water to prevent electrical risks.

Water suppression toolWater suppression toolWater suppression tool
Examples of water suppressed tools and machinery (Photos by WHSQ)

Note: Adding water to rotating tools causes water spray which also needs to be controlled.

On-tool extraction and local exhaust ventilation

This method removes dust as it is being produced. On-tool extraction is a type of local exhaust ventilation (LEV) system that fits directly onto the tool. This system consists of several individual parts – the tool, capturing hood, a H class dust extraction unit (or vacuum) and tubing.

Local exhaust ventilation can include fixed, portable or flexible capturing hoods could to capture dust at the point of generation.

Use a combination of LEV and water suppression if necessary.

Tool extraction
Examples of on tool extraction (photos courtesy of HSE)

Isolation

Providing distance between the work process and the worker, for example when operating bridge saws or routers, or providing distance between workers using hand tools will reduce exposure. Machinery can be fitted with plastic flaps or brush guards to direct water spray onto the slab or ground. Work process can be separated from other work areas by enclosing the immediate area floor to ceiling with plastic sheeting or using physical barriers such as portable screens. Respirable crystalline silica work processes can also be located outdoors away from other workers.

Food preparation and dining areas should be separated from fabrication to prevent food contamination and exposure during break times.

Plastic flaps Plastic flaps
Examples of on plastic flaps to contain water spray from a router and barriers between saw and operator (photos by WHSQ)

Work practices

Using wet processes generates excess water that can pool and dry on surfaces leaving dust deposits. Curbing and channelling can be used to capture excess water and remove it from the work area.

Ensure that workers wash their hands and face thoroughly before eating, drinking or leaving the workplace.

Personal protective equipment (PPE)

Plastic aprons and gumboots can be worn by workers to prevent clothing becoming wet and dusty. They are also easy to clean off at the end of the shift.

View our personal protective equipment webpage for further details.

Respiratory protective equipment (RPE)

When engineering and work practice controls do not completely limit silica exposures employers must provide workers with respiratory protective equipment (RPE) that must be worn during all tasks associated with risk of exposure to respirable crystalline silica. RPE does not prevent or control respirable crystalline silica from becoming airborne and should not be used as the primary means of control, but rather in combination with higher order controls like LEV or water suppression.

It is important to choose the right respirator for the job. The fit of a respirator to a worker's face is critical. Fit test workers to ensure the respirator is capable of giving the right level of protection.

There are two types of facial fit tests:

  • Qualitative – a pass/fail test that relies on the wearer’s ability to taste or smell a test agent.
  • Quantitative – uses specialised equipment to measure how much air leaks into the respirator and is not affected by the wearer’s sense of taste or smell, or their sensitivity to the test agent.

Quantitative fit testing results are objective and more reliable than qualitative testing which relies on a workers' ability to detect the testing agent by smell or taste. It is important to note many adults may have problems with their ability to taste or smell and can result in a potential for a false pass to the test. This can result in workers not being adequately protected against respirable crystalline silica.

It is important that fit testing is carried out by a competent person. You should take steps to ensure that the person who carries out the fit test is appropriately trained, qualified and experience, and is provided with appropriate information regarding each particular task. A competent person could be a reputable consultant or someone in-house or a representative from a RPE manufacturer or supplier.

When selecting the correct type of respirator, consider a powered air purifying respirator (PAPR) because of:

  • the amount of time the respirator is worn (for example a full shift)
  • physical demands of the task
  • potential for a hot and humid work environment.

Selection of RPE should be undertaken in accordance with AS/NZS 1715:2009 Selection, Use and Maintenance of Respiratory Protective Devices.

The HSE Video: Introducing Managing RPE in the workplace provides guidance on the selection and use of RPE.

View our respiratory protective equipment webpage for further details.

Health monitoring

Health monitoring is required for workers in this industry because there can be a significant risk to worker’s health if the exposure to RCS is not controlled. All workers must be provided with information about the purpose of health monitoring and a copy of their health monitoring results.

When health monitoring:

  • Inform workers about health monitoring and consult them about the choice of doctor.
  • Choose a suitable medical practitioner (for example any doctor who is a fellow of the Australian Faculty of Occupational and Environmental Medicine).
  • Make sure the doctor provides the following tests:
    • Demographic, medical and occupational history
    • Records of personal exposure
    • Standardised respiratory questionnaire
    • Standardised respiratory function test, for example, FEV1, FVC and FEV1/FVC
    • An ILO Standard Chest X-ray full PA view.
  • Obtain a health monitoring report from the doctor.
  • Give workers a copy of their results.
  • Provide WHSQ a copy of the report if:
    • The report recommends you take remedial measures at the workplace
    • The report indicates the worker has contracted a disease, injury or illness. (Any reduction in lung function is considered an injury.)
    • In either case the report can be supplied by emailing it to AOHHU@oir.qld.gov.au.

For further information about health monitoring for bench top fabrication workers consult the Stone bench top industry PCBU guide.(PDF, 663.78 KB)

You may already have the right controls in place, but are they all working properly?

  • When were controls last checked?
  • Are they always used when needed?
  • Is the respirable crystalline silica exposure controlled?

Controls must be reviewed at least once every five years or earlier in certain situations.

A competent person such as an occupational hygienist can carry out air monitoring to check if the controls are working.

Further guidance on reviewing controls for respirable crystalline silica can be found in the Silica - Technical guide to managing exposure in the workplace(PDF, 647.66 KB) .

Keeping records

All health monitoring and air monitoring reports must be kept for a period of 30 years after the record is made.

Resources

WHSQ guidance:

WHSQ reports:

Safe Work Australia guidance:

Australian Institute of Occupational Hygienists (AIOH) Guidance:

HSE (UK) guidance:

Last updated
25 October 2018

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