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An Introduction to Silica Dust: Definition, Sources, and Hazards 

11/12/2023by admin0Read: 6 minutes

In the pursuit of maintaining safe and healthy workplaces, Australian businesses face a myriad of occupational hazards. Among them, one often overlooked danger is silica dust—an invisible threat that can have severe consequences for both workers and organisations.

Silica dust, a microscopic airborne particle, poses a significant risk to workers across various industries. Hence, understanding what silica dust is and how it behaves is essential in comprehending its potential risks to human health.

As organisations strive to maintain safe and healthy workplaces, it becomes crucial to familiarise ourselves with this pervasive hazard.

This blog post introduces silica dust, exploring its definition, sources, and associated hazards.

What is Silica Dust?

Silica dust is generated in the workplace during mechanical processes such as cutting, crushing, drilling, grinding, sawing, or polishing natural stone or man-made products containing silica.

Silica dust particles are microscopic, typically ranging from 1 to 7 micrometres in diameter. Silica dust particles are not visible to the naked eye and can remain in the air for long periods, which workers can easily breathe. Inhaling very fine particles of crystalline silica can create a health hazard. The ‘respirable fraction’ refers to the size fraction of airborne dust that can reach the lungs where air exchange takes place. Particles larger than about seven microns (1 micron = 1/1000 mm) in diameter are no longer respirable.

Silica dust can exist in different forms, including crystalline silica (such as quartz, cristobalite, and tridymite) and non-crystalline or amorphous silica. Crystalline silica is the most concerning form due to its association with severe health hazards, while amorphous silica has lower toxicity. However, non-crystalline or amorphous forms of silica do not pose this risk.

The composition of silica dust can vary depending on the source and the processes involved. Whensilica materials are disturbed, fractured, or pulverised, such as during cutting, grinding, or crushing operations, tiny airborne particles are generated, resulting in silica dust.

Hence, understanding the composition of silica dust is crucial as it helps businesses and organisations recognise potential sources of exposure, assess risks, and implement effective control measures to protect workers’ health and prevent the onset of respiratory diseases associated with silica dust inhalation.

Sources of Silica Dust

Silica dust can originate from various sources across different industries and work environments.

Silica-containing products can emit dust particles during cutting, crushing, drilling, polishing, sawing, or grinding. Such minute particles can penetrate the lungs and lead to various health problems, including silicosis.

Understanding these sources is vital in implementing effective control measures to minimise exposure risks.

Here are some common contributors to silica dust along with their workplace:

1) Construction and Demolition: 

Construction sites and building demolition projects involving activities like cutting, drilling, grinding, or blasting of materials such as concrete, stone, brick, and tiles can generate significant amounts of silica dust.

2) Mining and Quarrying: 

Workers who work in mining and quarrying activities, especially those involved in drilling, blasting, and crushing rocks, ores, or minerals, may be at risk of being exposed to hazardous levels of silica dust.

3) Manufacturing and Foundries: 

Specific manufacturing processes produce silica dust, including sandblasting, grinding, polishing, or cutting of materials like glass, ceramics, or metal casting. Foundries that use silica-based materials for moulding and casting processes can also generate silica dust.

4) Sand Handling and Fracking Operations: 

Industries handling or processing sand, such as foundries, glass manufacturing, or hydraulic fracturing (fracking) operations, may generate substantial amounts of silica dust.

5) Stone and Concrete Work: 

Workers involved in stone cutting, carving, and shaping, as well as concrete manufacturing and cutting, are susceptible to silica dust exposure.

6) Abrasive Blasting: 

Any activity that utilises abrasive blasting methods, such as cleaning, stripping, or surface preparation, can generate significant amounts of silica dust if silica-based abrasives are used.

7) Ceramics and Pottery: 

Manufacturing processes in ceramics and pottery industries, such as clay preparation, moulding, and kiln operations, can release silica dust.

Silica Dust Exposure Hazards

In the workplace, a potential hazard is posed by crystalline silica or silica dust exposure, mainly when power tools are employed to modify products and materials containing them. This cutting process liberates silica dust, which can become airborne and inhaled by workers and others at the workplace.

In some workplaces, using machinery and products with a high silica content can dramatically increase the risk of exposure to silica dust.

Workers’ exposure to silica dust can pose various health risks, such as:

1) Acute Silicosis

Exposure to high levels of silica dust can lead to acute silicosis within weeks or years. It causes severe inflammation and protein buildup in the lungs.

If someone is exposed to moderate to high levels of silica dust for three to ten years, they may develop accelerated silicosis. This condition can cause inflammation, protein buildup in the lungs, and the formation of fibrotic nodules, which can cause scarring of the lungs.

2) Chronic Silicosis 

Chronic silicosis is a serious health concern that can develop from prolonged exposure to lower levels of silica dust. This condition is characterised by the growth of fibrotic nodules in the lungs, which can lead to shortness of breath. In severe cases, the nodules can aggregate and form progressive massive fibrosis, further exacerbating the condition. Organisations should take strict preventative steps to avoid exposure to silica dust and protect your health.

3) Kidney Damage

Prolonged exposure to Silica dust exposure can damage the kidneys of workers.

4) Scleroderma

Scleroderma is a condition that affects the body’s connective tissue, causing the formation of scar tissue in the skin, joints, and other organs.

5) Chronic Obstructive Pulmonary Disease (COPD)

Silica dust exposure can lead to chronic obstructive pulmonary disease (COPD), which includes conditions like emphysema and chronic bronchitis.

6) Lung Cancer

Lung Cancer (linked to silicosis) causes permanent lung scarring, stiffness, renal illness, and autoimmune conditions like scleroderma.

Silica dust can cause diseases with a long latency period, meaning that it may take years for the effects to become apparent or noticeable.

Measures Prevent Silica Dust Exposure 

As per the WHS Regulations model, PCBUs are responsible for managing the risks associated with handling, generating, storing, and using hazardous chemicals, such as silica. They must also ensure that workers are not exposed to crystalline silica beyond the workplace exposure standard and provide them with health monitoring. To manage these risks, PCBUs should select and implement control measures per the hierarchy of controls.

1) Eliminate Exposure to Silica Dust

To eliminate silica dust, it’s best to start by removing the processes that create it. Consider adopting production processes that generate less dust, such as wet methods instead of dry ones. You can also effectively tackle dust at its source by treating it right where it’s generated rather than trying to capture it later. Dust suppression techniques like water sprays, chemical additives, local exhaust ventilation (LEV), and vacuuming can help reduce dust on its transmission path.

2) Substitution

Substitution is a useful risk-management method to help organisations curb workers’ silica dust exposure.

To do this, businesses can:

  • Opt for products that don’t contain silica or have lower levels.
  • Choose silica-based products that don’t require cutting, grinding, or polishing.
  • Go for liquid or paste forms of silica products.

3) Isolate Workers

To effectively protect workers from silica dust exposure, it is essential to implement isolation controls. Organisations should follow safe work design principles by creating designated areas for tasks that generate dust. They should also ensure proper worker positioning during these tasks and use enclosures and automation to conduct dust-generating tasks. The fundamental goal should be to protect workers from the hazards of silica dust exposure.

When using powered hand tools, consider the proximity of other workers and designate a separate area for tasks like changing or eating. By implementing these isolation controls, workers can be safeguarded from silica dust exposure and work safely.

4) Workplace Ventilation

Selecting a suitable ventilation system for your workplace and tasks is crucial in effectively managing workplace hazards. Local exhaust ventilation, for example, can be used to eradicate silica dust at its source and prevent it from reaching workers’ breathing zones. Properly designed ventilation systems are a powerful tool in ensuring workplace safety.

Controls

1) Engineering Controls

Reducing the risk of dust exposure is achievable by implementing several engineering controls. These controls include local exhaust ventilation, the use of dust collection attachments on tools, and the application of water suppression techniques, also known as wet cutting.

2) Administrative Controls

Organisations should employ administrative controls in case of persisting risk, including good housekeeping policies, shift rotations and modifying cutting sequences.

One control may not be sufficient to prevent exposure; hence a combination of controls should be implemented to adequately protect workers.

3) Respiratory Protective Equipment 

Ensuring workers’ safety from silica dust particles is paramount. Workers should be given personal protective equipment, including suitable respiratory equipment (generally a minimum of a P2 efficiency half-face respirator) and work clothing that does not collect dust.

For workers to guarantee a suitable fit, it is important that they either have a clean-shaven face or facial hair that does not obstruct the fitting surfaces or the respirator valve. Since each individual’s face is distinct, there is no one-size-fits-all solution for tight-fitting respirators. Hence, testing each worker and their respiratory protective equipment (RPE) before commencing any dusty work is essential.

4) Housekeeping 

Establishing good housekeeping practices in the workplace can significantly reduce exposure to silica dust, even after work has ended. Developing written policies and rules is an effective method for implementing housekeeping as an administrative control.

5) Provide Training to Workers 

To ensure a safe workplace when working with silica or silica-containing products, it is imperative to have comprehensive training for employees. This training should cover the hazards of silica dust, the safety measures in place, and when employees are at risk due to poor work practices or ineffective controls. It is essential to provide this training during induction, refresher training, and when significant changes occur in the workplace. Workers should be motivated to report any hazards or safety issues immediately to prevent incidents or illnesses from occurring. By taking these precautions, we can ensure the safety and well-being of our employees.

Workplace Exposure Standard for Silica Dust

A workplace exposure limit of 0.05 mg/m3 (eight-hour time-weighted average) has been set for respirable crystalline silica (silica dust) to ensure worker safety. PCBUs are responsible for minimising worker exposure to silica dust as much as possible. In cases of uncertainty where the exposure limit is being exceeded or if there is a risk to a worker’s health, organisations should conduct air monitoring.

Anitech’s Occupational Hygienists can help you in implementing the above measures. You can call us at 1300 802 163 or email us at sales@anitechgroup.com

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