A risk assessment involves considering what could happen if your workers are exposed to a hazard and the likelihood of it happening.
If you have identified silica dust at your workplace or identified that it may be generated as part of your work practices, you should consider:
- how, where and for how long workers could be exposed to silica dust
- the control measures you have in place to control the dust, and
- the ways you can measure how well your control measures work.
Respirable silica dust is invisible to the naked eye and can hang in the air or a very long time after work has finished. Larger, visible dust particles settle long before invisible dust particles do, meaning workers can breathe in respirable dust even if they cannot see it in the air. It is important to consider whether workers (and other people in the workplace not working directly with silica) are at risk of exposure.
Respirable crystalline silica particles are less than 10 microns (µm) in diameter and when breathed in can reach deep into the lungs (see figure 2 below).
When assessing risk, you should consider if there are other airborne contaminants (fumes or mists) that workers could also be exposed to. It is important to consider if the control measures you have protect your workers from all possible exposures.
Example risk assessment Q & A: XYZ Paving Company
You own a small business that cuts and lays paving stones that contain silica.
Most cutting of paving stones is done outdoors using hand-held power tools. Cutting with a saw is normally carried out with a diamond blade, water suppression and on site. Block splitters are rarely used.
Very fine sand is also used when finishing laying stones. It is dry swept between the paving stones.
What is the hazard?
Workers can breathe in silica dust when cutting paving stones and when sweeping sand.
What is the harm?
Lung damage including cancer, bronchitis and silicosis.
Who may be harmed?
All workers undertaking cutting and sweeping tasks and workers and other people nearby.
What are you doing now?
- PPE for safety (steel-toe boots, protective work wear, hard hats, gloves)
- water to suppress dust
- cutting is done close to where pavers are laid
- some hoses are leaking and some attachments are broken
- slurry is not collected
- sand is dry swept
- goggles to protect worker’s eyes
- some are very old
- dust masks
- some workers have beards and don’t put them on
- hearing protection (ear plugs) for loud power tools
- workers nearby cutting don’t have ear plugs
What actions and improvements do you need?
- Designate cutting area further from where paving stones are laid to minimise dust and noise exposure to other workers
- Use wet methods to clean up and finish laying stones
- Check and repair water connections and hoses
- Collect slurry in a pan under the saw for disposal
- Implement maintenance schedule for equipment and PPE
- Provide PPE and RPE training for workers
- Review type of dust masks required for tasks
- Review clean shaven policy
- Replace old and faulty goggles
- Provide hearing protection to workers nearby cutting area
If your workers are cutting, grinding, sanding, drilling and polishing silica containing products or carrying out any activities that release silica dust into the air, then there is a significant risk that without effective controls they will be exposed to respirable silica dust and develop an illness or disease.
If your workplace has any work practices that generate dust from engineered stone products, there is a significant risk to the health of your workers and others.
Some tools release more silica dust into the air than others. Workers who use hand tools to cut or grind engineered stone (such as circular saws or grinders) can have some of the highest exposures to silica dust. These tools are often used to complete fabrication and installation tasks including cutting holes for sinks and stove tops or during shaping and joining.
In areas where hand tools are used, workers performing other tasks may also be exposed to high levels of dust.
Dry cutting, grinding or polishing engineered stone without water suppression and local exhaust ventilation generates very high levels of silica dust that far exceed the workplace exposure standard.
Many WHS regulators have now banned uncontrolled dry cutting of engineered stone due to the extreme risk that this practice poses to worker health. Please check with your local WHS regulator if this applies to you.
For further information about how to manage WHS risks, refer to the model Code of Practice: How to manage work health and safety risks. The model Code of Practice: Managing the risks of hazardous chemicals in the workplace also has information about how to conduct a detailed risk assessment for chemicals (including silica dust) at the workplace.
In Queensland, if you are installing a engineered stone benchtop you will need to prepare a safe work method statement (SWMS).For more information, refer to the model Code of Practice: Construction work.
There is a workplace exposure standard for respirable crystalline silica that must not be exceeded. The workplace exposure standard in Australia is 0.1 mg/m3.
You must do air monitoring to determine the airborne concentration of respirable crystalline silica at your workplace if:
- you are not certain if you are exceeding the exposure standard, or
- monitoring is necessary to find out if there is a risk to health.
Air monitoring can help in assessing the risk to your workers because it can show:
- how much your workers are being exposed
- which processes or products are the source of the exposure, and
- if your current control measures are working.
A competent person should conduct your air monitoring, for example a Certified Occupational Hygienist.
You must keep records of air monitoring for at least 30 years. You must also make sure that your workers can access these records. An air monitoring report should include:
- the background and purpose of the air monitoring including the current workplace exposure standard
- the task to be measured including work patterns and hazards involved with this task
- the control measures in place and their performance
- what sampling and measurements were taken (long and short-term) including information on the calibration of the sampling equipment
- specifics of how sampling was taken
- how and where the samples were analysed including information on the calibration of the analysis equipment
- an interpretation of the results:
- recommendations, for example:
- dust control action plan
- changing control measures and work practices
- worker training
- further air monitoring, and
- health monitoring.
Air monitoring at workplaces that work with silica containing products
There is insufficient evidence to show that any one combination of controls is guaranteed to keep exposure below the workplace exposure standard when working with silica containing products such as engineered stone.
When working with silica containing products, air monitoring will be needed to confirm whether the exposure standard for respirable crystalline silica is being exceeded.
It is recommended that air monitoring is carried out:
- at least once a year if you work with silica containing products
- if a worker becomes unwell or if a health monitoring report recommends you review your control measures
- if your work practices or the types of tools used change
- for example you use a new tool more often, and
- if new control measures are implemented or you change your control measures
- for example if you install an isolation booth or ventilation, or apply a new shift rotation.
If there is a risk to the health of your workers because of exposure to crystalline silica dust, you must organise and pay for health monitoring. This includes workers who are not directly generating dust but may be in the vicinity of silica dust or in contact with silica dust in other ways such as through cleaning work areas or equipment.
Some silica containing products, such as engineered stone, contain very high levels of silica and are considered to pose a significant risk to the health of workers that work with them. Under the model WHS laws, this means you must provide and pay for health monitoring for all workers involved in fabrication or installation of engineered stone products. You should also consider providing health monitoring to other workers who might be exposed to dust from these processes. This includes workers who are exposed to dust while cleaning or those who perform administrative work in the vicinity of fabricating products containing high levels of silica. Workers that should be provided health monitoring include:
- saw operators
- CNC router and water jet operators
- labourers, and
Health monitoring should begin at the time a worker is first employed or when they first start working with silica and silica containing products. This is so any changes to the worker’s health can be detected. If your workers have been working with silica, especially with engineered stone products and you have not provided health monitoring, you must organise it as soon as possible.
Health monitoring must be carried out or supervised by a doctor with experience. Health monitoring for silica dust includes workers being screened with specialised equipment. Depending on the worker’s past exposures and medical history, some doctors may recommend carrying out further tests with a specialist in order to detect early stage silicosis.
The doctor doing the health monitoring must provide you with a health monitoring report. You must keep the report for at least 30 years and the worker must receive a copy.
You must provide the health monitoring report to your WHS regulator if the doctor doing your monitoring:
informs you that a worker may have contracted a disease, injury or illness as a result of carrying out work using, handling, generating or storing silica, or
recommends that you take remedial measures (such as removing a worker from work).
In some jurisdictions, the doctor may be required to notify a worker’s disease diagnosis to the state or territory Department of Health.
If you are a PCBU that provides health monitoring, particularly if you share your duties with another duty holder, please seek further information from the health monitoring guide for PCBUs and health monitoring guide for crystalline silica.