RAMS for Silica Dust (RCS)

Respirable crystalline silica (RCS) is the fine fraction of silica dust — particles small enough to reach deep into the lung — generated whenever you cut, grind, drill, scabble or sand materials containing crystalline silica: concrete, stone, brick, mortar, block, tiles and most sandstone. It is a known human carcinogen (Group 1, IARC) and the primary cause of silicosis, an irreversible and potentially fatal fibrotic lung disease. There is no cure and no safe level of exposure; the legal duty is to drive exposure as low as reasonably practicable (ALARP), not merely below the limit.

Legal Basis

The duty to risk-assess RCS work falls under the Management of Health and Safety at Work Regulations 1999 (MHSWR 1999), Regulation 3, which requires a suitable and sufficient assessment of risks to workers and others. The Control of Substances Hazardous to Health Regulations 2002 (COSHH) then govern the specific arrangements for hazardous substances: you must prevent or, where prevention is not reasonably practicable, adequately control exposure. RCS carries a Workplace Exposure Limit (WEL) under EH40 of **0.1 mg/m³ (8-hour TWA, respirable fraction)**. Because it is a carcinogen, employers must apply the ALARP principle — hitting the WEL is a minimum floor, not a target.

Hierarchy of Controls

Controls must be applied in strict hierarchy order: eliminate first, PPE last.

**Eliminate or substitute.** Where practicable, redesign the work to avoid cutting silica-bearing materials on site entirely — factory-cut components or pre-formed openings remove the hazard at source. Substituting lower-silica materials (e.g. fibre-cement over dense concrete) can reduce generation but rarely eliminates it.

**Engineering controls.** These are the primary line of defence and must be in place before RPE is considered.

- **Water suppression** applied directly at the point of cutting or drilling keeps dust wet and prevents it becoming airborne. It must be continuous and correctly aimed — intermittent wetting is insufficient. - **On-tool local exhaust ventilation (LEV)** — shrouded angle grinders, vacuum-assisted core drills, dustless chasing systems — captures dust at source before it disperses. HSE evidence confirms that on-tool LEV combined with water suppression can reduce exposures below 0.1 mg/m³ for most tasks; either alone is rarely sufficient for high-energy cutting.

Verify LEV equipment meets H-class vacuum standard (filtration to ≥99.995%) and is maintained and examined at required intervals.

**Administrative controls.** Restrict access to the dust zone; rotate operatives to limit individual exposure duration; schedule high-dust tasks when fewer workers are nearby.

**RPE.** Respiratory protective equipment is the last resort, not a substitute for engineering controls. Where residual dust remains after engineering measures, **FFP3 disposable or reusable half-mask** is the minimum standard (assigned protection factor ~20). Face-fit testing is a legal requirement for tight-fitting facepieces — an untested or poorly fitted mask provides no reliable protection. Powered air-purifying respirators with a P3 hood (APF ~40) are appropriate where prolonged or higher-exposure tasks demand more protection. RPE must be compatible with other PPE (eye protection, hard hat).

**Health surveillance.** Because RCS is a carcinogen, COSHH requires health surveillance — typically lung function testing — for workers with regular exposure. Records must be kept for 40 years.

Common Failings in RCS RAMS

The most frequent weaknesses seen in RAMS documents include: listing RPE as the first or only control; failing to specify on-tool LEV and water suppression together; not identifying face-fit testing as a requirement; omitting health surveillance entirely; and quoting the WEL as a target exposure rather than an absolute ceiling requiring ALARP justification.

What an RCS RAMS Must Include

A compliant RCS RAMS should contain: identification of all tasks generating RCS and the silica-bearing materials involved; COSHH assessment referencing the EH40 WEL of 0.1 mg/m³ (respirable) and the carcinogen classification; engineering controls specified by task (water suppression, on-tool H-class LEV, enclosure where applicable); RPE specification with APF, face-fit test requirement and storage/maintenance arrangements; exposure monitoring arrangements where task-based evidence does not confirm control below the WEL; health surveillance programme; and supervisor responsibility for checking controls are in place before work starts each day.