UK trade-and-hazard guidance by the Riskora Editorial Team
Respirable crystalline silica (RCS) is the second largest occupational lung-disease killer in UK construction after asbestos. The HSE workplace exposure limit (WEL) is 0.1 mg/m³ over 8 hours — and a single hour of dry cutting concrete blocks can exceed that limit by an order of magnitude. COSHH 2002 requires the WEL to be controlled to 'as low as is reasonably practicable', and the only way to achieve that on most builder tasks is on-tool extraction (M-class) plus water suppression — RPE alone does not meet the COSHH duty.
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Control of Substances Hazardous to Health 2002
Regulations 6, 7 and 9
Assess exposure, prevent or adequately control, monitor controls. WEL for RCS is 0.1 mg/m³ as 8-hour TWA.
HSE CIS36 Construction Dust
All
On-tool extraction or water suppression for all dusty cutting and grinding. RPE (FFP3) as a back-up only, not as a primary control.
EH40 Workplace Exposure Limits
Table 1
RCS 8-hour TWA limit of 0.1 mg/m³ — must not be exceeded.
Every UK RAMS reviewer applies the hierarchy of controls in the order below. Defaulting straight to PPE is the single most common reason a RAMS fails review.
1. Eliminate
Order pre-cut blocks, lintels and slabs from the supplier — avoid on-site cutting wherever the design allows.
2. Substitute
Hand-cut with a guillotine for paving slabs (silent, dustless) instead of disc-cutting.
3. Engineering controls
M-class on-tool extraction (HEPA-filtered) on every disc cutter and grinder. Water suppression on cut-off saws (continuous flow, not just a wet mist).
4. Administrative controls
Cutting outdoors only, downwind of operatives. Job rotation to limit individual exposure. Health surveillance for any operative regularly cutting masonry.
5. PPE (last line)
FFP3 RPE (face-fit tested) as back-up. Safety glasses. Disposable coveralls if heavy cutting.
Listing RPE as the primary silica control without naming on-tool extraction or water suppression. COSHH 2002 explicitly demands engineering controls before PPE — any RAMS treating FFP3 masks as the main control will be rejected.
An illustrative extract structured for principal-contractor review. Site-specific facts must be substituted and checked by a competent person.
All masonry blocks have been ordered pre-cut to size from the supplier (ref order PO-2026-0118). The small volume of unavoidable on-site cutting will use a Mirka DEROS 5650CV cut-off saw fitted with M-class on-tool extraction (Mirka 1230 L PC, current PAT cert) and continuous water suppression. Cutting will be carried out outdoors at the south side of the site, downwind of the welfare unit. Operatives will wear FFP3 RPE (face-fit tested, current cert on file) as a back-up to the engineering controls. Health surveillance arranged for the lead bricklayer (annual lung-function check) per COSHH Reg 11.
Daily extractor pre-use check (filter condition, vacuum performance). RPE seal check at sign-on. Photo log of cutting position relative to operatives. Annual health surveillance.
Is FFP3 enough on its own for cutting blocks?
No. COSHH 2002 demands engineering controls (extraction or water suppression) before PPE. FFP3 RPE is a back-up to the engineering controls, not a substitute. RAMS that treat masks as the primary silica control will fail any competent review.
What is the silica exposure limit?
0.1 mg/m³ as an 8-hour time-weighted average (HSE EH40). Dry cutting blocks indoors can exceed that limit in minutes; the controls are designed to stay well below it across the working day.
Do builders need silica health surveillance?
Yes — under COSHH Reg 11, any operative regularly exposed to a hazardous substance with a WEL must be under health surveillance. For silica that means annual lung-function checks and respiratory questionnaire by an occupational health provider.
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