WorkSafe Victoria provides guidance and information on dealing with crystalline silica dust in construction
Crystalline silica is a natural mineral found in construction materials such as concrete, bricks, tiles, mortar and engineered stone. It includes substances such as quartz, cristobalite, tridymite or tripoli.
Common materials and their typical crystalline silica content include:
- sandstone: 70 to 90 per cent
- granite: 25 to 60 per cent
- ceramic tiles: 5 to 45 per cent
- autoclaved aerated concrete: 20 to 40 per cent
- slate: 20 to 40 per cent
- concrete: less than 30 per cent
- porcelain: 14 to 18 per cent
- brick: 5 to 15 per cent
- marble: less than 5 per cent
- engineered stone: 1 per cent or more crystalline silica, determined as a weight/weight concentration
Crystalline silica dust is generated when these substances are mechanically processed – for example, through construction activities such as cutting or grinding. These dust particles are small enough to be breathed deep into the lungs.
Health conditions
Exposure to crystalline silica dust over a long period at low to moderate levels, or short periods at high levels, can lead to serious health conditions such as silicosis, WorkSafe Victoria warns.
Silicosis is an irreversible, incurable and progressive lung disease that can lead to disability and death.
Construction and demolition employees can be at risk of developing these diseases.
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WorkSafe Victoria says employers have duties to manage risks from crystalline silica dust under Part 4.1 (Hazardous substances) and Part 4.5 (Crystalline silica) of the Occupational Health and Safety Regulations 2017 (OHS Regulations).
Under the OHS Regulations, employers must ensure employees are not exposed to respirable crystalline silica dust at the workplace at a level above the exposure standard.
The exposure standard for crystalline silica dust, listed under Quartz, Cristobalite, Tridymite, Tripoli (respirable dust), is 0.05mg per cubic metre as a time-weighted average (TWA) airborne concentration over eight hours.
An eight-hour TWA exposure standard is the maximum average airborne concentration of a particular substance permitted over an eight-hour working day, for a five-day working week.
Where a workplace has working hours that exceed an eight-hour day or a 40-hour week, the TWA needs to be adjusted to compensate for the greater exposure.
WorkSafe Victoria recommends that employees are not exposed to levels above 0.02mg per cubic metreas an eight-hour TWA.
This is a precautionary measure to prevent silicosis and to minimise the risk of lung cancer.
What is a crystalline silica process?
A crystalline silica process means one or more of the following processes carried out at a workplace:
- The use of a power tool or other form of mechanical plant to cut, grind, polish or crush material containing crystalline silica or to carry out any other activity involving material containing crystalline silica that generates crystalline silica dust
- The use of a roadheader on an excavated face if the material in the face contains crystalline silica
- A process that exposes a person to crystalline silica dust arising from the manufacture or handling of material that contains crystalline silica
- The mechanical screening of crushed material containing crystalline silica
- A quarrying process involving material containing crystalline silica
- A tunnelling process involving material containing crystalline silica
- A process determined by WorkSafe to be a crystalline silica process
High risk work
High risk crystalline silica work (HRCSW) is an engineered stone process, or work performed in connection with a crystalline silica process that is reasonably likely to result in an airborne concentration of respirable crystalline silica that exceeds half the exposure standard for respirable crystalline silica, or a risk to the health of a person at the workplace.
Before starting a crystalline silica process, an employer or self-employed person must identify whether the crystalline silica processes are HRCSW, WorkSafe Victoria says.
This must be done by conducting a risk assessment or by choosing to treat that work as HRCSW without doing a risk assessment.
If doing a risk assessment, the employer or self-employed person must consider the following factors:
- The specific tasks or processes required to be undertaken with material that contains crystalline silica.
- The form of crystalline silica to be used, for example: brick, concrete, crushed rock.
- The proportion of crystalline silica contained in the material.
- The previous atmospheric monitoring results.
- The likely frequency and duration of exposure to crystalline silica dust.
- Any information about incidents, illnesses or diseases associated with exposure to crystalline silica dust at the workplace.
Hazard control statement
A crystalline silica hazard control statement is a document prepared for HRCSW carried out at a workplace.
Similar to a safe work method statement (SWMS) for high risk construction work, it sets out the hazards and risks arising from the work and details the measures to control those risks and how they will be implemented.
If the HRCSW is being undertaken as part of high risk construction work, the hazard control statement can be incorporated into a SWMS.
WorkSafe VIC advises an employer or a self-employed person must not perform HRCSW unless:
- a crystalline silica hazard control statement is prepared for the work before the work begins, and
- the work is performed in line with that hazard control statement
Hiring and training
WorkSafe VIC also says employers must ensure that applicants for jobs involving high risk crystalline silica work are given information about the health risks associated with exposure to respirable crystalline silica; the need for measures to control those risks; and details about the control measures.
Information, instruction and training needs to be provided to employees who are likely to be exposed to risks associated with undertaking high risk crystalline silica work, the organisation adds, including on:
- the health risks associated with exposure to crystalline silica dust
- the need for any risk control measures required by the OHS Regulations
- the proper use of any risk control measures required by the OHS Regulations
- how the risk control measures are to be implemented
Atmospheric monitoring
Atmospheric monitoring, or air monitoring, for crystalline silica involves sampling the air for respirable crystalline silica within the employees’ breathing zone.
WorkSafe Victoria states that by law, employers must carry out atmospheric monitoring if they are not sure if their employees are exposed to levels of silica dust that are above the exposure standard; or they can’t work out if there is a risk to employee health without air monitoring.
Employers should also carry out atmospheric 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 an HSR requests a review of control measures because there is uncertainty based on reasonable grounds as to whether the exposure standard is or may be exceeded
- if there are changes to the workplace exposure standard, and previous atmospheric monitoring results have indicated levels above the new standard.
The interpretation of these results, including comparison with the exposure standard, should be carried out by a competent person, to determine employee exposure to crystalline silica dust. An occupational hygienist is an example of a competent person.
Results of air monitoring must be shared as soon as reasonably possible with employees who have been or may have been exposed, WorkSafe Victoria says.
Employers must also ensure health monitoring is carried out for an employee if exposure to crystalline silica is reasonably likely to have an adverse effect on the employee’s health.
Health monitoring must be done under the supervision of a registered medical practitioner and should be carried out by a specialist occupational and environmental physician or respiratory physician with expertise in respiratory and silica exposure health monitoring.
For more information, go to www.worksafe.vic.gov.au