Silica Dust -- The Exposure Limit & Controls
Silica Dust -- The Exposure Limit & Controls
Cutting, grinding or drilling concrete, brick or stone releases respirable crystalline silica -- and breathing it causes silicosis, an incurable lung disease. The exposure limit and the controls that keep you under it.
The exposure limit
| Respirable crystalline silica (RCS) OEL | 0.1 mg/m3 (cut from 0.4 mg/m3 in 2008) |
| Heads-up | Industry commentary in late 2025 discussed a NEW lower silica limit phasing in -- do not treat 0.1 as safe headroom; check the current OEL with the DEL |
| The regime | Regulations for Hazardous Chemical Agents 2021 (silica is a Schedule 2 HCA) |
The controls (in order)
| 1. Eliminate or substitute | Avoid the dusty method where you can |
| 2. Engineer it out | Wet cutting, on-tool water feeds, local exhaust ventilation for indoor work |
| 3. Administrative | Limit time and the number of people exposed |
| 4. Respiratory protection (last) | An FFP3 or P3 half-mask is the minimum for silica; a comfort paper mask does NOT stop respirable silica |
The duties that go with it
- Air monitoring must be done by an outside Approved Inspection Authority (AIA), not in-house
- Exposed workers go on medical surveillance (spirometry and chest X-rays); silicosis is compensable under COIDA
- Dry-cutting with no respiratory protection can earn a prohibition notice that stops the job on the spot
Reference only -- not medical or legal advice. The 0.1 mg/m3 limit may be lowered; verify the current OEL with the Department of Employment and Labour before you design controls around it. Verify at labour.gov.za.
Sources: Regulations for Hazardous Chemical Agents 2021 (OHS Act) · Department of Employment and Labour · NIOH
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