Controlling Dust on Site: Silica and the Hidden Dangers

Dust is one of construction’s most underestimated hazards. It looks harmless, but the fine particles you can’t see, especially respirable crystalline silica (RCS) from cutting, grinding, drilling, or crushing concrete, brick, stone and mortar, can reach deep into the lungs and cause life-limiting disease. In the UK, the legal framework is clear: you must assess, prevent, and control exposure, and prove you’re doing it

Why Silica Dust is so Dangerous

Silica is a natural mineral in many common building materials. When those materials are worked, they generate RCS; tiny particles small enough to bypass the body’s defences. Long-term exposure can cause silicosis, COPD, and lung cancer; some effects can appear surprisingly quickly with high exposures.

The Legal Exposure Benchmark (WEL)

In Great Britain, RCS has a Workplace Exposure Limit (WEL) of 0.1 mg/m³ (8-hour TWA). Your goal is always to reduce exposure to as low as reasonably practicable (ALARP) and at least below the WEL. Recent HSE research and guidance continues to reference this WEL and emphasises rigorous control.

The UK Regulations You Need to Know

COSHH Regulations 2002 (as amended)

Require you to assess risks, prevent or adequately control exposure, maintain controls, monitor exposure where needed, provide RPE where necessary, and arrange health surveillance when there’s a reasonable likelihood of disease. EH40/2005 lists the WEL for RCS used with COSHH.

Management of Health and Safety at Work Regulations 1999

Require a suitable and sufficient risk assessment that underpins your COSHH assessment and site controls. (HSE cross-refers to risk assessment duties throughout its construction dust guidance).

Construction (Design and Management) Regulations 2015 (CDM)

CDM Regulations 2015 puts duties on clients, designers, and contractors to plan, manage and monitor work, including health risks like dust, throughout the project. (HSE’s construction dust pages are part of this wider duty framework).

Health Surveillance for RCS

HSE refreshed its G404 guidance in 2025. If workers are regularly exposed to RCS or exposure is likely to be significant, you must provide appropriate health surveillance (e.g. questionnaires, spirometry) via a competent provider. Keep records and act on the findings.

RPE Fit Testing

If you use tight-fitting RPE (e.g. FFP3, half masks), every wearer must have a face-fit test for the specific make/model/size, plus training and ongoing checks. HSE’s current fit-testing basics page is explicit: RPE can’t protect if it leaks.

Practical Controls that Actually Work (and satisfy COSHH)

Think hierarchy of control. Start at the top and only rely on RPE after you’ve reduced dust at source.

Eliminate or Substitute the Task/Material

Use prefabricated components or off-site cutting where feasible.
Specify lower-silica materials for non-structural elements where technically acceptable.

These options align with COSHH’s duty to prevent before controlling.

Engineer Out the Dust at Source

Water Suppression: For cut-off saws, block/paver cutting, floor saws and breakers, use an effective, continuous water feed to dampen dust. Maintain flow, use proper hoses/nozzles, and avoid “token” misting. HSE’s task-specific CN sheets set the benchmark here.
On-tool Local Exhaust Ventilation (LEV): Use shrouds/hoods connected to a suitable vacuum with high-efficiency filtration and automatic filter cleaning. Keep hoses short and intact; check capture at the point of dust generation. HSE’s CN sheets describe good practice.
Enclose or Isolate the Process: Temporary screening, isolation zones, or working outdoors where possible to dilute and disperse residual dust.

Administrative Controls

Plan the Sequence: Minimise simultaneous dusty trades; schedule high-dust tasks when fewer workers are nearby.
Good Housekeeping: Wet-wipe or use suitable vacuums; never dry sweep.
Maintenance and inspection: Check water feeds, shrouds, seals, vacuums, and filters every shift; record defects and fix promptly.

Respiratory Protective Equipment (RPE)

Select RPE with an Assigned Protection Factor (APF) that matches the task and residual exposure after engineering controls. For many silica tasks, FFP3 or P3 filters (APF 20) are typical. Always confirm via your risk assessment and HSE’s RPE guidance (HSG53). Train wearers; store and maintain correctly.
Face-fit Test: Ensure tight-fitting masks and manage facial hair policy; re-test on change of mask type or significant facial changes.

Monitoring: Prove Your Controls Work

Under COSHH, you may need air monitoring to confirm that exposures remain below the WEL and ALARP. Focus on higher-risk tasks (e.g. dry cutting, abrasive blasting, tunnelling, demolition). Use competent occupational hygienists; sample to UK methods and compare results to the 0.1 mg/m³ (8-hr TWA) RCS WEL. HSE research shows that with well-managed controls, most demolition exposures can be kept well below the limit, evidence that good controls work.

Health Surveillance: What “Good” Looks Like

Where indicated, your programme should:

Identify at-risk workers and start surveillance before or soon after exposure begins.
Include symptom questionnaires, lung function testing (spirometry) at set intervals, clear referral pathways, and feedback into your risk controls.
Keep secure records and act on early signs, then adjust tasks, improve controls, and review RPE.

Quick, Task-Based Controls

Cut-off Saws (Blocks/Kerbs): Water suppression plus on-tool extraction where applicable; FFP3/P3 RPE if residual dust remains.
Handheld Drilling/Coring: On-tool extraction or water where practicable; consider RPE and local isolation.
Crushing/Screening Demolition Arisings: Robust water sprays; sealed, filtered cabs for plant; hygiene controls.
Abrasive Blasting: Very high risk. Use specialist enclosures, high-APF RPE, rigorous supervision and monitoring.

Compliance Checklist (UK)

COSHH assessment covering silica sources, tasks, duration, and people affected. Reference EH40/2005 WELs.
Plan controls using the hierarchy; adopt HSE’s task sheets as the standard of good practice.
Select and maintain RPE to HSG53; face-fit test and train users.
Air monitoring where needed; keep results and review after changes in methods or equipment.
Health surveillance for workers with significant RCS exposure, per HSE’s updated G404.
Information, instruction, and training. Conduct toolbox talks on dust hazards and controls; supervision and enforcement of rules (e.g. no dry sweeping).
Review and Audit. Use findings from monitoring and surveillance to improve controls and update the risk assessment.

Toolbox Talk: Five Non-Negotiables

Water on, extraction on, every cut, every hole.
No dry cutting or dry sweeping, ever!
Wear the right mask, the right way, with a fit test on your model.
Keep cabs closed and filters maintained; don’t track dust into welfare areas.
Report dust issues immediately; pause work if controls fail.

Final Thoughts

Silica’s danger is “hidden” because the most harmful particles are invisible. But the duties, and the solutions, are visible and achievable. If you plan the work, choose the right controls, prove they work, and look after your people with fit-for-purpose RPE and health surveillance, you’ll protect lungs and stay on the right side of UK law.
For practical, task-specific methods, use HSE’s construction dust pages and CN sheets as your default playbook.

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