HSE describes respirable crystalline silica as the biggest risk to construction workers after asbestos. This guide covers what silica is, the legal exposure limit under UK law, and how to protect a team on site — including the workers a tight-fitting mask leaves out.
Who’s most at risk: high-exposure silica tasks
HSE flags these common tasks as generating high levels of respirable silica. If your team does any of them, silica should be in your risk assessment:
- Cutting, grinding or polishing stone and engineered worktops
- Cutting or chasing blockwork, brick and concrete
- Grinding, scabbling or breaking concrete
- Cutting paving, kerbs and roof tiles
- Demolition, tunnelling and quarrying
- Sweeping settled dust (it puts it straight back in the air)
What is respirable crystalline silica (RCS)?
Silica occurs naturally in stone, sand, concrete, mortar and many building materials. Cutting, grinding, drilling and dressing these materials releases fine respirable crystalline silica — particles small enough to reach deep into the lungs. Regular exposure over time causes silicosis, an incurable, progressive scarring of the lung tissue, and raises the risk of COPD, lung cancer and other diseases.
HSE estimates that hundreds of construction workers die each year from past silica exposure. It is preventable — but only if it is controlled.
The UK exposure limit: 0.1 mg/m³
The UK workplace exposure limit for respirable crystalline silica is 0.1 mg/m³, averaged over an eight-hour day, published in HSE’s EH40. It is one of the lowest limits of any workplace substance.
Important: 0.1 mg/m³ is a legal maximum, not a “safe” level.
HSE requires exposure to be reduced as low as reasonably practicable, not simply kept under the limit. Staying below 0.1 mg/m³ is a legal minimum — not a guarantee that no harm is being done.
What the law requires: COSHH and the control hierarchy
Under COSHH 2002, employers must assess the risk and control exposure through a hierarchy: eliminate the dust where possible, then control it at source with water suppression (wet cutting) and on-tool extraction (LEV), and only then rely on respiratory protective equipment for the residual risk. RPE is the last line of protection, not the first.
What RPE do you need for silica?
The right RPE depends on the exposure level in your risk assessment. As a minimum, many silica tasks need APF 20; higher exposures need APF 40. Here’s how the common options compare:
| Respirator option | APF | Fit test needed? | Works over a beard? |
|---|---|---|---|
| FFP3 disposable mask | 20 | Yes | No |
| Half mask + P3 filters | 20 | Yes | No |
| Full-face mask + P3 filters | 40 | Yes | No |
| TH2P powered hood | 20 | No | Yes |
| TH3 loose-fitting PAPR (PiONAiR range) | 40 | No | Yes |
There is a problem, though. FFP3 and other tight-fitting masks only work on a clean-shaven face, and they need a fit test. If a worker has a beard, they are not getting the rated protection.
Protecting the whole team
A loose-fitting TH3 powered respirator delivers APF 40 — twice the protection of an FFP3 — with no fit test and full compatibility with facial hair. For silica-exposed teams that include bearded workers, it is often the only way to protect everyone to the right level and stay compliant.
Where PiONAiR fits
PiONAiR makes a range of loose-fitting, positive-pressure powered respirators: the P900 Visor, H500 Hardhat Visor, RX-3000 All-in-One, and the S300 and S350 hoods. Every one is EN 12941:2023 TH3, APF 40. They need no fit test, work over a beard, and suit silica-heavy tasks in construction, stone and concrete fabrication, demolition and quarrying. Which model fits depends on the job and the headgear already in use.
→ Ask us about protecting your silica-exposed teams. Book a free on-site audit.
Frequently asked questions
What is the safe limit for silica dust?
There is no “safe” level. The UK legal maximum is 0.1 mg/m³ over eight hours, and HSE requires exposure to be reduced as low as reasonably practicable below that.
What respirator should I use for silica dust?
At least APF 20 (FFP3, P3 half mask or TH2P) for many tasks, and APF 40 (full-face P3 or TH3P powered respirator) for higher exposures. Base it on your risk assessment.
What silica respirator works with a beard?
A loose-fitting TH3 powered respirator, such as those in the PiONAiR range, gives APF 40 with no fit test and works over facial hair.
Sources: HSE, “Construction dust” and silica guidance (silica the biggest risk to construction workers after asbestos; hundreds of deaths a year from past exposure); HSE EH40/2005 Workplace Exposure Limits (RCS WEL 0.1 mg/m³, 8-hour TWA); COSHH Regulations 2002.
PiONAiR provides guidance on product use, but this does not constitute professional health & safety advice. Suitability of PPE remains the responsibility of the employer or end user.