When utilizing handheld grinders for purposes other than mortar removal, such as smoothing or cutting surfaces of concrete, masonry, or other materials containing silica, it's crucial to recognize that this activity can generate respirable crystalline silica dust. Inhaling these minute silica particles over time can result in irreversible lung damage.
To mitigate potential exposure, WorkCover Queensland advises the following controls in accordance with Appendix 4 of the Managing respirable crystalline silica in construction and manufacturing of construction elements code of practice 2022 (PDF, 1.71 MB):
Use suitable engineering controls
Consider the following engineering control options:
- An integrated water delivery system providing a continuous water feed to the grinding surface (for outdoor use only).
- A grinder equipped with a commercially available shroud and dust collector that:
- Provides at least 25 cubic feet per minute (cfm) of airflow per inch of blade (roughly 700 liters per 25mm of blade diameter).
- Is rated to either M-Class or H-Class.
- Has a cyclonic pre-separator or filter cleaning mechanism.
Wet methods
Grinders with an integrated water delivery system can effectively control dust when cutting, grinding, or polishing materials containing crystalline silica outdoors. Outdoors, water-fed grinders excel at dust control on uneven surfaces, near corners, and edges compared to vacuum dust collection systems. Ensure to clean up slurry before it dries to prevent the release of silica dust into the air.
Dust collection system
Alternatively, a dust collection system can be employed to control dust when using a handheld grinder. Compliance includes ensuring the dust collection system:
- Features a commercially available shroud designed to fit the grinder and wheel size.
- Provides at least 25 cfm of airflow per inch of blade (roughly 700 liters per 25mm of wheel diameter) for effective dust capture.
- Is equipped with a cyclonic pre-separator.
- Holds a rating of M-Class or H-Class in accordance with AS/NZS60335.2.69.
Select appropriate respiratory protective equipment (RPE)
The type of RPE required depends on factors such as the engineering controls in use, the duration of the task during the shift, and the location where the work is being undertaken.
RPE is not required when wet cutting (outdoors only) but is required if using dust extraction. Half face reusable or disposable RPE has a minimum protection factor (MPF) of 10.
| Engineering control used | Time spent doing task during shift | |
|---|---|---|
| Equal or less than 4 hours | Greater than 4 hours | |
| Wet cutting (Option 1) | RPE not required | RPE not required |
| Dust extraction (Option 2) | Outdoors RPE not required | Outdoors RPE not required |
| Indoors / enclosed area RPE not required | Indoors / enclosed area P1 or P2 filtered RPE with a MPF 10 required | |
For tight fitting RPE, workers must be fit-tested to the specific make and model before using it. See section 7.6 of the Code (PDF, 1.71 MB) for more information on fit-testing and other requirements for using RPE.
A PCBU must provide health monitoring to a worker if their tasks require them to wear RPE 30 times or more in 12 months. See section 10 of the Code (PDF, 1.71 MB) for more information on health monitoring requirements.