This article examines measuring crystalline silica in stone, typical crystalline silica content levels for common building products, and reducing your risk of exposure to the harmful dust.
Knowing which materials are likely to contain crystalline silica is an important step in avoiding the hazardous dust and minimising the risk of exposure. Stone Initiatives works with the construction and manufacturing industries Australia-wide, to analyse stone samples and related building products for the presence of crystalline silica or other potentially hazardous components. Get in touch to arrange testing, and read on to learn more about measuring crystalline silica in stone.
Context
The harmful nature of exposure to crystalline silica dust is increasingly the focus of media coverage around Australia, as state and federal workplace safety ministers consider a ban on engineered stone (which often contains high levels of crystalline silica). While some work has already been done to reduce the risk associated with dust production caused by dry cutting (with dry cutting the stone now banned in some states), Safe Work Australia says exposure to respirable crystalline silica at work continues to be an issue of national significance.
The RACGP has described it as an emerging occupational health epidemic, saying urgent action is needed to better protect workers. A report by Curtin University states that more than 10,000 Australians are predicted to develop lung cancer in their lifetime as a direct result of being exposed to crystalline silica dust.
What is crystalline silica?
Crystalline silica is a common mineral that can be found in construction materials such as some natural stone types, engineered stone, concrete, bricks, tiles and mortar. Crystalline silica is considered hazardous when it is in respirable form, i.e. as inhalable dust. Crystalline silica dust can be generated when a material containing crystalline silica is cut or ground, such as in manufacture, construction, demolition or in a laboratory setting. These dust particles can be breathed deep into the lungs and can lead to serious irreversible health conditions such as lung cancer and silicosis – a disease that can lead to disability and death.
Silica is silicon dioxide, a naturally occurring and widely abundant mineral that forms the major component of most rocks and soils. It is important to note that there are non-crystalline (i.e. amorphous) and crystalline forms of silicon dioxide. Crystalline silicon dioxide (crystalline silica) is the dangerous form of silicon dioxide known to cause lung damage; amorphous silica is not known to cause this lung damage. The most common type of crystalline silica is quartz.
How is crystalline silica measured?
Stone Initiatives can analyse your stone sample or product for the presence of crystalline silica or other potentially hazardous components. Measuring the crystalline silica content of your stone is a vital step in understanding the level of risk.
Stone Initiatives can facilitate crystalline silica content analysis with one of two main methods:
- X-Ray diffraction analysis of crystalline mineral components or
- Petrographic analysis of a thin section sample
These tests can be targeted to detect the presence of and identify the proportion of crystalline silica or other deleterious/hazardous components within a stone sample. It is important to note that the results produced by these methods are estimations and are based on the sample submitted for testing. There is a detection limit and limitations with the accuracy of the proportions determined for crystalline silica percentage.
Typical crystalline silica levels in building products
Common products and their typical crystalline silica content include:
- engineered stone: 40% to 95%
- ceramic tiles: 5% to 45%
- autoclaved aerated concrete: 20% to 40%
- concrete: less than 30%
- brick: 5% to 15%
Additionally, below are typical crystalline silica content ranges for some common natural dimension stone products:
- Quartzite and sandstone: 20% to 95%
- Granite: 5% to 50%
- Bluestone and basalt: typically less than 10%
- Limestone: typically less than 5%
- Marble: typically less than 5%
Not every stone type will fall within these typical ranges for crystalline silica content. If you are unsure if a stone or product contains crystalline silica, check the safety data sheet (SDS) or other information from the manufacturer or supplier. Stone Initiatives can also analyse a sample of the material or product in question, to determine the presence of crystalline silica or any other features of concern, such as naturally occurring asbestos minerals.
Higher-risk stone types such as engineered stone slabs, sandstones, quartzites and granites should be analysed to determine their crystalline silica content. Likewise, testing is often required for all on-site processed materials for projects where crystalline silica quantity is controlled.
Crystalline silica dust control measures
If a material such as engineered stone does contain crystalline silica, it is vital that the appropriate measures are taken to control the dust during processing activities such as manufacture, construction or demolition.
According to Safe Work Australia, the workplace exposure standard for respirable crystalline silica (silica dust) that must not be exceeded is 0.05 mg/m3 (eight-hour time weighted average).
However, exposure to silica dust should be kept as low as reasonably practicable. Air monitoring must be conducted if there is any uncertainty that the exposure standard is being exceeded or to find out if there is a risk to a worker’s health.
Safe Work Australia outlines the following controls:
- substitution such as sourcing composite stone benchtops with a lower percentage of silica
- isolation of the hazard – using principles of safe work design to designate areas for tasks that generate dust and appropriate worker positioning during these tasks, using enclosures and automation to conduct dust generating tasks
- engineering controls that minimise the risk of exposure to generated dust, for example, local exhaust ventilation, water suppression (wet cutting) or using tools with dust collection attachments
- should a risk still remain; administrative controls, including good housekeeping policies, shift rotations and modifying cutting sequences
- should a risk still remain; personal protective equipment including appropriate respiratory equipment (generally a minimum of a P2 efficiency half face respirator) and work clothing that does not collect dust.
For more information on measuring crystalline silica in stone, or for naturally occurring asbestos enquiries, email Thomas Baggs at tbaggs@stonemtg.com.au
Disclaimer: This article is for informational purposes only. It is not intended to be a substitute for professional medical advice. Always seek the guidance of your doctor or other qualified health professional with any questions you may have regarding your health or a medical condition.
More information can also be found here: https://www.cancer.org.au/cancer-information/causes-and-prevention/workplace-cancer/silica-dust