One of the most serious dust hazards in New Zealand workplaces — and how to control it
Respirable crystalline silica (RCS) is a fine dust released when materials like stone, concrete and especially engineered stone are cut, ground or polished. Breathing it in can cause accelerated silicosis, an irreversible lung disease. New Zealand's workplace exposure standard for RCS is 0.025 mg/m³ (8-hour average), and every business working with these materials must control the dust at source. Engineered stone is not currently banned in New Zealand (unlike Australia), but the risk is real and the rules are under review.
It is the fine, breathable fraction of silica dust — small enough to reach deep into the lungs.
Crystalline silica occurs naturally in concrete, bricks, rocks, stone, sand and clay, and in very high concentrations in artificial or engineered stone used for kitchen and bathroom benchtops. When these materials are cut, ground, drilled or polished, they release respirable crystalline silica — particles fine enough to be inhaled deep into the lungs, where they cause lasting damage. You cannot see the most dangerous particles, and a workplace can look clean while the air is hazardous.
It can contain over 90% crystalline silica — far more than natural stone.
Engineered (or artificial) stone benchtops can contain in excess of 90% crystalline silica, compared with under 45% for natural granite. Fabricating it — cutting, edging and polishing slabs — can generate very high concentrations of RCS, which is why it has been linked to accelerated silicosis: a more aggressive form of the disease that appears sooner and can progress faster than the chronic silicosis seen historically in miners and stonemasons. Silicosis is irreversible and progressive, and the only treatment for advanced disease is a lung transplant.
Not currently — but the rules are being actively reviewed.
Australia banned the manufacture, supply, processing and installation of engineered stone from 1 July 2024. New Zealand has taken a different path so far: rather than a ban, it has lowered the exposure standard, published guidance, and supported a voluntary industry accreditation programme. MBIE has consulted on control options — including a possible ban — and provided advice to the Minister, so the position may change. Because this is a live policy area, always confirm the current legal requirements before relying on this guide.
General information, not legal advice. The regulation of engineered stone and RCS in New Zealand is under active review and may change. Always check the current position with WorkSafe NZ and MBIE.
Keep airborne RCS below the workplace exposure standard, so far as is reasonably practicable.
Under the Health and Safety at Work Act 2015 and the hazardous substances and general risk regulations, a PCBU must eliminate or minimise exposure to RCS so far as is reasonably practicable, and keep airborne levels below the workplace exposure standard of 0.025 mg/m³ as an 8-hour time-weighted average. This standard was lowered from 0.05 mg/m³ in November 2023. Meeting it generally requires a combination of controls, air monitoring by a competent person such as an occupational hygienist, and health monitoring for exposed workers.
Work down the hierarchy — eliminate first, rely on PPE last.
| Control level | Examples for silica / engineered stone |
|---|---|
| Eliminate | Use low- or zero-silica materials; buy pre-cut or finished products so high-dust tasks are avoided. |
| Substitute / isolate | Switch to lower-silica alternatives; separate dusty work from other areas and workers. |
| Engineering controls | Wet cutting and water suppression; on-tool extraction (local exhaust ventilation); never dry-cut engineered stone. |
| Administrative | Safe work procedures, restricted access, housekeeping (no dry sweeping or compressed air), training, air and health monitoring. |
| PPE | Properly fitted respiratory protection (RPE) appropriate to the exposure — the last line, not the first. |
Dry processing of engineered stone is a particularly high-risk practice. Source: WorkSafe NZ guidance on silica dust.
Exposed workers should be in a health monitoring programme.
Because early silicosis often has no obvious symptoms, workers exposed to RCS should have regular health monitoring so disease can be detected as early as possible. In New Zealand, an accelerated silicosis assessment pathway has been established to help eligible engineered stone workers get their health checked. Health monitoring sits alongside — not instead of — controlling the dust at its source.
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The workplace exposure standard for respirable crystalline silica is 0.025 mg/m³ as an 8-hour time-weighted average. It was lowered from 0.05 mg/m³ in November 2023. Airborne RCS must be kept below this level so far as is reasonably practicable.
Not currently. Australia banned engineered stone from 1 July 2024, but New Zealand has so far managed the risk through a lower exposure standard, guidance and voluntary accreditation. The government has consulted on options including a possible ban, so the position may change — always check the current rules.
Accelerated silicosis is an aggressive, irreversible lung disease caused by exposure to high levels of respirable crystalline silica, such as from cutting engineered stone. It appears sooner and can progress faster than chronic silicosis, and advanced disease can only be treated with a lung transplant.
Work down the hierarchy of controls: eliminate or substitute with low-silica materials where you can, use wet cutting and on-tool extraction, never dry-cut engineered stone, apply good housekeeping and safe work procedures, and use properly fitted respiratory protection as the last line. Back this up with air and health monitoring.
If workers are or may be exposed to RCS, exposure (air) monitoring by a competent person such as an occupational hygienist helps confirm your controls are working, and health monitoring helps detect early signs of disease. Both should support, not replace, controlling the dust at source.
