What is silica dust?

Silica is an abundant mineral found in the earth’s crust, it has a wide variety of industrial uses. Crystalline silica dust, which can become airborne, if not properly contained, can become hazardous to workers who inhale it.

Silica dust is generated when certain workplace mechanical processes are performed on natural stone or synthetically manufactured products such as cutting, drilling, polishing, grinding and crushing.

In some cases, these silica particles can be so small that they’re not visible to the naked eye; those kind of particles are called respirable silica dust particles. If inhaled too deeply, respirable silica dust can lead to irreversible lung damage.

Which workplace activities generate silica dust particles?

Workplace activities that generate respirable silica dust particles includes:

• Fabrication and installation of composite (engineered or manufactured) stone countertops,
• Excavation, earth moving and drilling plant operations,
• Clay and stone processing machine operations,
• Paving and surfacing,
• Mining, quarrying and mineral ore treating processes,
• Tunnelling,
• Construction labouring activities,
• Brick, concrete or stone cutting; especially using dry methods,
• Abrasive blasting with blasting agents containing no more than 1% crystalline silica,
• Foundry casting,
• Angle grinding, jack hammering and chiselling of concrete or masonry,
• Hydraulic fracturing of gas and oil wells,
• Pottery making.

Do rocks and rock products contain silica?

What happens when you are exposed to silica dust?

Exposure to silica dust can lead to a variety of serious health issues, including:

• Acute Silicosis – Intense exposure to very high levels of silica dust causes severe inflammation and an outpouring of protein into the lung.
• Accelerated Silicosis: Exposure to moderate-to-high levels of silica dust, leads to inflammation, protein in the lung, and scarring (fibrotic nodules).
• Chronic Silicosis: Long-term exposure to lower concentrations of silica dust causes shortness of breath.
• Lung Cancer
• Kidney Damage

Best silica control measures?

A Workplace Exposure Standard (WES) is the concentration of a hazardous chemical (such as respirable crystalline silica) in the air a worker breathes, that is not expected to result in any adverse health consequences or excessive injury. WHS laws at the federal, state and territorial levels mandate adherence to the WES.

There is a limit of 0.05 mg/m3 (8-hour time weighted average) for exposure to respirable crystalline silica (silica dust) in the workplace.

The prolonged exposure of workers to silica dust should be minimised using PCBUs to the maximum extent possible. If there is any doubt that the exposure standard is being exceeded, or if there is a concern for an employee’s health, then air monitoring must be performed.

When it comes to the use, handling, generation and storage of hazardous substances like silica, PCBUs have special responsibilities under the model WHS Regulations. In addition to ensuring that employees are not exposed to more crystalline silica than is allowed by law, PCBUs must also monitor their employees’ health.

Selecting and executing steps using the hierarchy of controls can help manage hazards and worker exposures to silica:

Hazard isolation – using safe work design principles to designate areas for tasks that generate dust and appropriate worker positioning during these tasks, using enclosures and automation to conduct dust generating tasks substitution measures such as sourcing composite stone benchtops with a lower percentage of silica

If the risk of exposure to generated dust persists despite the use of engineering controls such as local exhaust ventilation, water suppression (wet cutting), or the use of tools with dust collection attachments, then the following measures should be taken:

• Good housekeeping policies;
• shift rotations;
• Modifying cutting sequences; and
• Personal protective equipment, including appropriate respiratory equipment (generally a minimum of a P2 efficiency).

In most cases, a combination of controls will be necessary to ensure the safety of employees.

Safe Work Australia’s response to silica exposure at work

Safe Work Australia’s CEO Michelle Baxter is taking a stance in response to the continued issue of respirable crystalline silica at work. At the end of February, Australia’s work health and safety ministers agreed to implement Safe Work Australia’s additional regulation recommendations for high-risk activities involving silica containing materials, as well as further investigate a prohibition on engineered stone.

Additionally, ministers recognised the necessity to increase awareness and changing behaviours in order to educate PCBUs and workers about the risks involved with working with silica. In order to achieve this, Safe Work Australia has already begun carrying out initiatives proposed by WHS ministers while consulting various stakeholders including industry and unions for a unified national approach. After their call-out for submissions, SWA received over 100 responses from different sources that contributed to informing their report for WHS ministers for consideration and decision making regarding this issue.

How to ensure that silica dust exposure is within WES standards at your workplace?

In order to ensure that the Silica Dust Workplace Exposure Standard (WES) is not exceeded, business owners and managers may need to take additional precautions or modify existing practices.

To reduce the risk of silica dust exposure to your employees, consider the following five measures:

• Evaluate your exposure to silica dust in the workplace.
• Ensure that your employees are not overexposed to silica dust by reviewing the preventative measures you have in place.
• If the silica dust levels at your job are unknown, you should arrange for air monitoring.
• You should consult with your staff and any health and safety reps (HSRs) to discuss the lowered WES, its potential effects on the workplace, and any necessary training changes.
• If there is silica dust in the workplace, either in the air or on the surfaces of individuals who work with it, you should evaluate your health monitoring programme for employees.

Nationally Recognised Silica awareness courses

AlertForce’s health and safety Silica courses outlines the outcomes needed to recognise the hazards and risks inherent in working with products containing crystalline silica. It also explains how to plan and implement safe work practices that reduce exposure to the mandatory limits. 10830NAT is the national course code.

If you are a person conducting a business, the above guide will help you understand the risks of Silica further and help you make safer decisions faster. See Safe Work Australia