What is crystalline silica?
Crystalline silica is a natural mineral found in construction materials such as concrete, bricks, tiles, mortar and engineered stone.
The amount of crystalline silica in products can vary. Examples include:
- engineered stone: 80% to 95%
- ceramic tiles: 5% to 45%
- autoclaved aerated concrete: 20% to 40%
- concrete: less than 30%
- brick: 5% to 15%
- marble: less than 5%
If you're not sure if a product contains crystalline silica, check the safety data sheet (SDS) or other information from the supplier.
Dust containing respirable crystalline silica particles is commonly called silica dust.
Activities such as cutting, grinding, sanding, drilling, loading or demolishing products that contain silica can generate respirable particles of crystalline silica dust that are small enough to breathe into your lungs. This dust may not be visible.
Crystalline silica dust can be harmful when it's inhaled into your lungs over a long period of time at low to moderate levels, or short periods at high levels.
When crystalline silica dust is inhaled it can cause silicosis, 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 lead to death.
Breathing in silica dust can also cause other serious diseases, such as:
- lung cancer
- kidney disease
- autoimmune disease, such as scleroderma
Construction and demolition employees can be at risk of developing these diseases.
Safe Work Australia publishes exposure standards for airborne contaminants in the workplace.
The exposure standard for crystalline silica dust (listed under Quartz (respirable dust)) is 0.05mg/m3 as a TWA (time-weighted average) airborne concentration over 8 hours.
An 8-hour time-weighted average exposure standard is the average airborne concentration of a particular substance permitted over an 8-hour working day and 5-day working week.
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 0.02mg/m3 as a TWA. This is a precautionary measure to prevent silicosis, and to minimise the risk of lung cancer.
Controlling exposure risk
Employers must control the risk associated with exposure to crystalline silica by applying the hierarchy of control in Part 4.1 of the Occupational Health and Safety Regulations 2017 (OHS Regulations).
An employer must, so far as is reasonably practicable, eliminate the risk associated with exposure to crystalline silica in their workplace (for example by not using crystalline silica-containing products).
If it is not reasonably practicable to eliminate a risk associated with crystalline silica, the employer must reduce the risk so far as is reasonably practicable by:
- engineering controls (see below) or
- a combination of any of the above risk control measures
If the risk of exposure still remains, these controls must be added:
- administrative controls (eg housekeeping, work practices)
- personal protective equipment (for example respiratory protective equipment)
You may need more than one control to control the risk sufficiently.
- Construction tasks and exposure
Exposure to crystalline silica can occur during common construction and demolition tasks when working with concrete, bricks, mortar, tiles, stone or other masonry.
If employees regularly dry cut, grind, crush, drill, sweep or demolish these materials without engineering controls in place, it is likely that the exposure standard will be exceeded. For example, employees may be exposed to higher levels of respirable crystalline silica when doing certain tasks, such as concrete cutting or tuck-point grinding.
Effective dust controls, such as on-tool water suppression or on-tool dust extraction, need to be used when these tasks are performed. WorkSafe Victoria views these controls to be reasonably practical in all but very rare situations.
Where it is not possible to use engineering controls, tasks that involve exposure to crystalline silica (other than work on engineered stone) may be performed for a very short period of time over the day, as it is unlikely that the exposure standard will be exceeded (assuming no exposure for the remainder of the shift). An example is overhead drilling for a total of 15 minutes or less (Occupational Safety and Health Administration USA, 2017).
Construction workers may be exposed to higher levels when engineered stone benchtops are being cut on the construction site. For more information about controlling these risks:
- Engineering controls
- Administrative controls
- Respiratory protective equipment (RPE)
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 employee health, and therefore if health monitoring is required.
Air monitoring and the interpretation of results (including comparison with the exposure standard) needs to be conducted by a competent person (such as an occupational hygienist) to determine employee exposure to crystalline silica. Results of air monitoring must be shared with employees who have been, or may have been, exposed. Where possible, air monitoring results should be shared with medical practitioners who are conducting health monitoring for employees.
Employers must provide health monitoring if exposure to crystalline silica is likely to have an adverse effect employees' health. This is particularly important where lower level control measures, such as RPE are relied on to reduce exposure.
Health monitoring is required for employees who are exposed to silica dust at levels likely to exceed the exposure standard.
Health monitoring must be undertaken by a registered medical practitioner. It needs to be carried out by an occupational physician who is a fellow of the Australasian Faculty of Occupational and Environmental Medicine (AFOEM), with expertise in respiratory and silica exposure health monitoring. A list of practitioners can be found on the Royal Australasian College of Physicians website (link below). Employers should speak to the occupational 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.
For more information on health monitoring see Crystalline silica health assessments (link below).
Crystalline silica: Safety basics
Changes to protect Victorians working with engineered stone
Working with engineered stone
Crystalline silica health assessments
Stonemasons: Preventing crystalline silica exposure
RACP: Find an AFOEM consultantExternal link
AIOH: Find an occupational hygienistExternal link
Dust containing crystalline silica in the extractive industry