Silica Dust Exposure

Silica (Silicon dioxide) is found in stone, rocks and sand and is also a major component of many construction materials including concrete, bricks, tiles, and mortar. When it is freshly ‘fractured’ through processes such as stonecutting, drilling, and polishing, it creates a fine enough dust to reach deep inside the lungs when inhaled. As RCS particles are invisible to the naked eye, high concentrations can be inhaled without the worker being aware of it.

It is estimated up to 600,000 Australian workers each year are potentially being exposed to silica dust – a progressive respiratory condition that can lead to death through exposure to respirable crystalline silica (RCS). Although this affects workers across a wide range of industries, the engineered stone benchtop industry is only one of many industries where workers are exposed to silica.

Silicosis

Silicosis is widely recognised as the most common chronic occupational lung disease worldwide.

It is a progressive, degenerative clinical respiratory condition which causes crippling health conditions and co-morbidities and can lead to death.

Silicosis presents predominantly as an upper lung condition and symptoms can take many years to emerge, although after very heavy exposure it can develop more quickly – after as little as a few months. There is often extensive damage to the lungs before any symptoms appear and as the condition progresses, the symptoms increase.

It is likely that many people being exposed to silica dust in their workplace are unaware of the very real danger it poses. It is also possible that many employers are not aware of the risk. Education is therefore key in any effort to combat the condition.

By implementing a series of risk reduction strategies (including monitoring dust levels, taking steps to reduce exposure to RCS, educating workers about the risks of RCS and providing high-quality RPE) employers can keep their workers safe. While cases of occupational silicosis are underreported, and so it is hard to gauge the full cost to companies due to staff absence, individuals with silicosis have been awarded damages of up to $2m.

At risk industries

Workers in the below industries are particularly at risk:

• Construction and demolition
• Mining and quarrying
• Pottery and glass manufacturing
• Stone masonry and stone cutting
• Worktop manufacturing and fitting
• Sandblasting

Implementing a hierarchy of control

Under the model WHS Regulations, PCBUs have specific duties to manage the risks to health and safety when using, handling, generating, and storing hazardous chemicals, including silica. PCBUs also have a duty to ensure the workplace exposure standard for crystalline silica is not exceeded and to provide health monitoring to workers.

The WorkSafe Act states the hierarchy of control is as follows:

1. Eliminate risks - Use materials that do not contain crystalline silica.
2. Reduce the risk by substitution – use materials with a lower crystalline silica content or use fibre cement sheet sheers instead of circular saws.
3. Isolation – use automated machines, fully enclosed operator cabins, or apply exclusion zones.
4. Reduce the risk using engineering controls – no dry cutting, use wet methods and use well-positioned local exhaust ventilation.
5. Administrative controls – design shift rotation limit task times, and design housekeeping and cleaning policies.
6. Personal Protective Equipment (PPE) – provide respiratory protective equipment (RPE) with a suitable protection factor.

The role of PPE

In many instances, risks cannot be controlled by engineering controls alone and businesses need to provide their staff with high-quality PPE.

Furthermore, staff should be properly trained to use to use, check and clean the RPE. There should be systems in place to make sure that disposable respirators are changed regularly, the filters on reusable RPE respirators are changed in accordance with the manufacturer’s recommendations and the equipment is stored in a clean, dust-free place. Staff should also be empowered to report any problems (such as defective, old, or badly fitting RPE) to their supervisor.

When choosing RPE it is very important to remember not only to use masks that have a high filtration efficiency, such as a P3 Respirator, but also to make sure that the mask fits properly.

Face fit testing for tight-fitting RPE is the process of checking the seal between the mask and the wearer's face to ensure that the mask is properly fitted and able to provide effective protection against airborne particles. The purpose of fit testing is to identify any gaps or leaks between the mask and the face that could allow dust to enter the wearer's respiratory system.

It is important to note that face fit testing should be performed by a trained professional during the initial selection process of tight-fitting RPE, it also needs to be repeated if there are changes to the wearer's face, such as weight loss or gain, or if the mask model or size is changed. Regular fit testing is also recommended to ensure that the tight-fitting RPE continues to provide adequate protection over time, the recommended time is to re-test every 1-2 years which is recommended by SafeWork Australia in their National Guidance Material.

Links:

Managing-silica-dust-at-construction-sites.pdf (act.gov.au)

Crystalline silica and silicosis - Choosing and implementing control measures for silica dust | Safe Work Australia

Occupational dusts | Australian Government Department of Health and Aged Care