Controlling silica dust exposure

Article originally published by WorkSafe Queensland

Following the first of our series on Queensland’s new construction silica code of practice, this article highlights what steps you should take to choose the right silica dust controls at your workplace.

Business operators must ensure nobody in the workplace is exposed to a level of respirable crystalline silica (RCS) that is higher than the workplace exposure standard (WES), and must remove or reduce the risks from RCS as much as possible.

Note

The workplace exposure standard (WES) for RCS is 0.05 milligrams per cubic metre (mg/m³) averaged over an eight-hour period (8-h time-weighted average or TWA).

Further information on the WES is provided in Section 1.3 of the new code.

Using the right dust controls will reduce the amount of RCS released. If higher order controls such as dust extraction and water suppression are not able to keep exposures below the WES, respiratory protective equipment (RPE) is required.

The Managing respirable crystalline silica dust exposure in construction and the manufacturing of construction elements code of practice 2022 outlines two methods for choosing the right controls.

1. Choosing the right controls – controls table

The new code of practice includes a controls table at Appendix 4. The table lists 33 common tasks, and outlines tried and tested dust controls.

If the dust controls are used correctly for all tasks at the workplace, the PCBU can be certain on reasonable grounds that workers’ exposure to RCS is below the WES.

2. Choosing the right controls – hierarchy of controls

If the PCBU does not use Appendix 4, the PCBU must follow the hierarchy of controls to manage the risk of exposure to RCS. This means you must eliminate the risk, for example by using materials that do not contain 1 per cent or more crystalline silica, or if this isn’t practicable, you must minimise exposure risks by:

• substituting the hazard (for example using mechanical shears, or score and snap, on fibre-cement sheeting, rather than a circular saw)
• isolating the hazard (for example enclosing the equipment that generates RCS, or establishing an exclusion zone)
• using engineering controls (for example local exhaust ventilation, water suppression).

If the risk of RCS exposure remains after using the above controls, you must use the following controls to minimise the risk:

• administrative controls (for example rotating workers to minimise the time spent on work that generates RCS)
• respiratory protective equipment (for example providing workers with a suitable breathing mask).

A combination of controls is the best way to reduce exposure to RCS (for example using a grinder fitted with a suitable dust extraction system, and wearing a respirator). You can only be certain that the controls you have in place have reduced exposure to RCS below the WES if you have statistically valid exposure data from air monitoring.

All dust controls used must be included in:

• for construction work: a safe work method statement
• for manufacturing of construction elements: the workplace’s WHS risk management plan.

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