The Health and Safety Executive has made water suppression a legal requirement when cutting, grinding, or polishing engineered stone — the silica-rich material used in kitchen worktops, bathroom surfaces, and commercial fit-outs. Dry cutting of engineered stone is now prohibited under the Control of Substances Hazardous to Health Regulations 2002 (COSHH), following a formal amendment that came into force in late 2024.
If your COSHH assessments haven't been updated to reflect this change, you are already operating outside the law.
Why engineered stone is different from natural stone
Engineered stone — sometimes called quartz composite or sintered stone — contains up to 93% crystalline silica. Natural granite, by comparison, typically contains 25–30% silica. When engineered stone is cut, ground, or polished, it releases respirable crystalline silica (RCS) dust at concentrations that can be many times higher than the Workplace Exposure Limit (WEL) of 0.1 mg/m³.
Prolonged exposure to RCS causes silicosis — an incurable, progressive, and potentially fatal lung disease. Cases of accelerated silicosis (where the disease develops within five years of first exposure) have been recorded in young workers in the UK, Australia, and the United States, all linked to engineered stone fabrication and installation.
What the new legal requirement means in practice
The HSE amendment to COSHH specifically prohibits dry cutting of engineered stone. This means:
- Water suppression is mandatory — all cutting, grinding, and polishing of engineered stone must use integrated water suppression systems that wet the cutting point continuously
- On-tool extraction alone is not sufficient — LEV (local exhaust ventilation) without water suppression does not meet the new requirement for engineered stone specifically
- Respiratory protective equipment (RPE) remains required — even with water suppression, operatives must wear suitable RPE (minimum FFP3 or P3 half-mask) when working with engineered stone
- Health surveillance is required — any worker regularly exposed to RCS must be enrolled in a health surveillance programme
What you need to update in your COSHH assessments
If your business installs, fabricates, or works with engineered stone, your COSHH assessments must now explicitly reflect the following:
Substance identification
Engineered stone must be identified as a substance containing very high concentrations of crystalline silica. The assessment must reference the specific silica content of the materials used (available from the manufacturer's SDS).
Control hierarchy
Your assessment must demonstrate that you have applied the COSHH control hierarchy — elimination, substitution, engineering controls, administrative controls, PPE — in that order. For engineered stone, this means:
- Elimination/substitution: consider whether lower-silica materials can be used
- Engineering controls: water suppression systems on all cutting equipment
- Administrative controls: task rotation, limiting exposure time, wet cleaning only
- PPE: FFP3 disposable or P3 half-mask respirator, disposable overalls, eye protection
Monitoring and health surveillance
The assessment must include arrangements for air monitoring (to verify that controls are keeping exposure below the WEL) and health surveillance for all regularly exposed workers.
Don't wait for an inspection
HSE inspectors are actively targeting engineered stone fabricators and installers following the regulatory change. Improvement notices and prohibition notices have already been issued to businesses found dry cutting without water suppression.
Updating your COSHH assessments now — before an inspection — is not just good practice. It's a legal requirement.
SafetyPod's COSHH Assessment Template covers all the required elements under the updated regulations, including substance identification, control hierarchy, monitoring arrangements, and health surveillance. It's designed for use on real sites, not just for filing.
What contractors need to update in their COSHH assessments
The HSE ban on dry cutting is not a minor administrative change — it requires a substantive review of any COSHH assessment that covers engineered stone work. A COSHH assessment that still lists dry cutting as a permissible method, or that lists on-tool LEV as the primary control without water suppression, is now legally non-compliant.
The following elements must be reviewed and updated in every COSHH assessment covering engineered stone fabrication, cutting, grinding, or polishing:
1. Substance identification and hazard classification
Engineered stone must be explicitly identified as a substance containing very high concentrations of respirable crystalline silica (RCS) — typically 70–93% by weight. The COSHH assessment must reference the relevant WEL of 0.1 mg/m³ (8-hour TWA) for RCS and note that engineered stone generates dust concentrations that can exceed this limit by a significant factor even with some controls in place.
2. Control hierarchy — water suppression as a mandatory primary control
Under the amended COSHH requirements, the control hierarchy for engineered stone must now place integrated water suppression at the top. The assessment must state clearly that:
- Dry cutting of engineered stone is prohibited by law
- Water suppression must be continuous and integrated into the cutting tool — not applied manually or intermittently
- On-tool LEV (local exhaust ventilation) without water suppression does not satisfy the legal requirement for engineered stone specifically, even if it meets requirements for other stone types
- Where water suppression is temporarily unavailable, work must stop — there is no acceptable dry-cutting alternative
3. RPE specification
Even with water suppression in place, RPE remains a required control for engineered stone work. The COSHH assessment must specify the minimum RPE standard: FFP3 disposable respirator or a P3 half-mask with appropriate filter. FFP2 is not sufficient for engineered stone. The assessment should also document the face-fit testing requirement — RPE only provides its rated protection when properly fitted to the individual wearer.
4. Health surveillance
Any worker regularly exposed to RCS — including those working with engineered stone — must be enrolled in a formal health surveillance programme. The COSHH assessment must reference this requirement and confirm that health surveillance is in place. This is not optional: failure to provide health surveillance for workers exposed to RCS is a specific enforcement target for HSE inspectors.
5. Review date and version control
A COSHH assessment that has not been reviewed since before the ban came into force must be updated and re-dated. The review should be documented and signed by a competent person. Where the assessment is used across multiple sites or projects, all copies must be updated — not just the master document.
Minimum PPE and controls now required for engineered stone work
To summarise the minimum legal standard for any contractor working with engineered stone following the HSE ban:
- Water suppression: Continuous, integrated water suppression on all cutting, grinding, and polishing tools. No exceptions.
- RPE: Minimum FFP3 or P3 half-mask for all operatives working with or near engineered stone during cutting or grinding operations. Face-fit tested and individually assigned.
- LEV: On-tool LEV should still be used where practicable as a supplementary control, but it does not replace water suppression.
- Health surveillance: Formal programme in place for all regularly exposed workers, with records maintained.
- Training: All operatives must be informed of the specific risks of engineered stone, the reasons for the ban on dry cutting, and the correct use of water suppression equipment and RPE.
- Supervision: Adequate supervision to ensure controls are being used correctly on every job — not just when an inspector might be present.
This is part of a broader enforcement focus by the HSE on silica dust across the construction industry. For a full picture of the inspection programme and what HSE inspectors are looking for on site, see our guide to HSE's wider silica dust inspection crackdown.
Download the COSHH Assessment Template and ensure your assessments meet the current legal standard.