Demolition Dust Control: COSHH Assessment, Water Suppression, LEV and Silica Dust Management Plan

Summary

Silica dust is the hidden killer of the demolition industry. Respirable crystalline silica — the fine dust released when concrete, brick, mortar, stone, and sandstone are cut, broken, or crushed — causes silicosis, an irreversible and potentially fatal lung disease. Silicosis takes years to develop and is entirely preventable, yet it remains a significant occupational health problem in UK construction. The HSE estimates that construction-related lung diseases cause more than 3,500 deaths per year — a figure that dwarfs the number of immediate traumatic fatalities.

COSHH Regulations 2002 require employers to assess the risk from hazardous substances, prevent or adequately control exposure, and monitor controls. For demolition, this means a specific COSHH assessment for dust, a written Silica Dust Management Plan on sites where significant silica exposure is likely, health surveillance for workers with regular silica exposure, and documented control measures including LEV and RPE. Demolition is explicitly identified by HSE as one of the highest-risk activities for silica exposure — the same risk level as tunnelling and quarrying.

A common misconception is that dust controls are optional or that a dust mask is enough. A standard paper dust mask (FFP1 or FFP2) does not provide adequate protection against respirable crystalline silica at demolition levels of exposure — FFP3 disposable respirators or TH3P powered air-purifying respirators (PAPRs) are the minimum requirement. On-tool LEV (local exhaust ventilation — vacuum extraction fitted directly to the tool) reduces dust at source and should always be the first line of defence before relying on RPE.

Key Facts

• RCS WEL: 0.1 mg/m³ TWA (8-hour) under the Control of Substances Hazardous to Health Regulations 2002 — this is a legal limit, not a guideline
• RSP (Respirable Suspended Particulate) WEL: 4 mg/m³ TWA (8-hour) — the general dust limit, but RCS limit is far more restrictive and controls demolition work
• COSHH assessment is a legal requirement before work with demolition dust begins — must be suitable and sufficient, in writing, and specific to the task
• Hierarchy of controls under COSHH: Elimination → Substitution → Engineering controls (LEV/water suppression) → Administrative controls → RPE — RPE is the last line of defence, not the first
• LEV (Local Exhaust Ventilation): on-tool vacuum extraction fitted directly to grinders, drills, disc cutters, and scabblers; reduces exposure by up to 90% compared to uncontrolled cutting
• Water suppression: continuous wetting of the work face during breaking, drilling, and cutting — reduces airborne dust at source, required where LEV is impractical
• FFP3 disposable respirators: minimum RPE class for silica dust — FFP1 and FFP2 are inadequate
• TH3P powered air-purifying respirators (PAPRs): preferred over disposable FFP3 for extended periods of heavy exposure; more comfortable and provide higher protection factor (APF 20 vs APF 20 for FFP3)
• Face-fit testing is mandatory for all tight-fitting RPE (FFP3 disposable and half-mask respirators) — a poor fit renders even an FFP3 mask ineffective
• Air monitoring: personal exposure monitoring (carried by the worker) or static monitoring required when controls are first implemented or when process changes — check against WEL
• Medical surveillance required under COSHH Regulation 11 for workers with significant ongoing RCS exposure — lung function testing at baseline and periodic intervals
• HSE INDG463: "Dust in the workplace" — key guidance document for construction dust risk
• Site boundary monitoring: required on sites adjacent to sensitive receptors (hospitals, schools, housing) — typically real-time PM10/PM2.5 monitors
• BOHS W401 certificate: industry standard qualification for dust management — required by many principal contractors before operatives can work in high-dust environments
• Silica content: concrete typically 25–50% crystalline silica; brick 20–35%; sandstone up to 70% — all create high RCS exposure when broken or cut
• Wet demolition: a complete demolition method using water cannon or irrigation to suppress dust throughout — used where water supply and drainage can be controlled

Quick Reference Table

Detailed Guidance

COSHH Assessment for Demolition Dust: What It Must Cover

A COSHH assessment for demolition dust must be written, task-specific, and documented before work starts. A generic "construction dust" COSHH assessment covering the whole site is insufficient — each distinct task with different materials or exposure levels requires its own assessment.

The assessment must identify: the substance and its hazards (RCS from concrete/brick/mortar; wood dust; gypsum dust; general inhalable dust); who is exposed (including bystanders — labourers, plant operators in adjacent areas); the likely duration, frequency, and intensity of exposure; whether the WEL is likely to be exceeded; and the control measures in place.

For demolition specifically, the assessment must address each demolition method: hand breaking with hammer, mechanical demolition with excavator-mounted processor, disc cutting of concrete slabs, scabbling, grit-blasting, high-pressure water jetting. Each creates different dust profiles and requires tailored controls.

The COSHH assessment must be reviewed whenever there is a significant change in materials, methods, or exposure levels, and at least annually for ongoing operations.

Water Suppression: Rates, Methods, and Limitations

Water suppression reduces airborne dust by binding fine particles as they are generated. It is the primary engineering control where LEV is impractical — for example, with large hydraulic breakers, excavator-mounted processors, and bulk concrete breaking where a vacuum hose cannot be attached to the tool.

Effective water suppression requires continuous wetting — not occasional wetting. The work face must remain visibly wet throughout the operation. Typical water application rates: hand breakers 1–2 litres/minute; disc cutters 0.5–1 litre/minute at the blade; bulk breakers 5–20 litres/minute. Water should be applied via a hose positioned as close to the point of impact as possible, not sprayed generally over the work area.

Water suppression has limitations. It is ineffective in freezing conditions. It creates mud and water runoff that may require drainage management. It does not fully eliminate fine respirable dust — water binds larger particles but smaller respirable particles (<4 microns) are not fully captured. Water suppression should therefore always be used alongside RPE, not as a substitute for it.

For large-scale demolition, fixed or temporary misting systems can be installed at the demolition face or around the perimeter to provide continuous suppression. These are particularly effective for bulk concrete breaking and crusher operations. Dust suppression cannons (mist cannons) are used for large open sites where portable equipment is impractical.

LEV: On-Tool Extraction in Demolition

LEV (local exhaust ventilation) means capturing dust at the point of generation before it enters the air. In demolition, this means vacuum extraction units fitted directly to power tools: angle grinders with shrouds and vacuum attachments, core drills with vacuum extraction, scabblers with vacuum shrouds, and disc cutters with integrated extraction.

The LEV system must be adequate for the task. For RCS-generating tasks, the vacuum unit must produce sufficient airflow to capture the fine dust — typically H-class (high filtration) vacuum extractors rated to filter particles down to 0.3 microns. M-class vacuums are inadequate for silica dust. H-class vacuums are identified by their HEPA filter rating and are marked "H" on the unit.

LEV must be examined and tested at least every 14 months under COSHH Regulation 9, and inspection records maintained for 5 years. In practice, filters should be inspected daily in demolition environments and replaced when blocked. A blocked filter reduces airflow and negates the LEV's effectiveness — operatives will often continue working with a blocked vacuum, believing LEV is in place when it is not. Daily filter checks by the site supervisor are essential.

Not all demolition operations can use on-tool LEV — bulk breaking with hydraulic hammers and excavators, wrecking ball operations, and large-scale concrete crushing cannot use direct attachment LEV. For these operations, water suppression is the primary engineering control, supplemented by RPE.

RPE Selection: FFP3, TH3P, and Face-Fit Testing

RPE is the last line of defence — it does not reduce dust at source but protects the wearer from residual exposure after engineering controls have been applied. For silica dust in demolition, the minimum RPE class is FFP3 (disposable filtering facepiece, class 3) or TH3P (powered air-purifying respirator with P3 filter).

FFP3 disposable masks provide an Assigned Protection Factor (APF) of 20, meaning they reduce concentration by a factor of 20 at the face. They must be individually face-fit tested — a mask that does not seal against the face provides little or no protection regardless of its filter class. Face-fit testing is required for every wearer (faces vary significantly in shape) and must be repeated if the wearer's face changes (weight loss, dental work, beard growth).

TH3P powered air-purifying respirators (PAPRs) — helmets or hoods with a battery-powered blower and P3 filter — provide an APF of 20 but do not require face-fit testing because they use a loose-fitting hood. They are more comfortable for extended wear and are preferred for workers doing heavy physical work in high-temperature conditions where a tight-fitting mask becomes impractical. PAPRs are the preferred RPE for demolition operatives who spend extended periods in dusty environments.

Beards prevent an adequate face seal for tight-fitting RPE. Workers with beards cannot use FFP3 disposable masks and must use TH3P powered hoods. This is a non-negotiable safety requirement — do not allow bearded workers to use tight-fitting RPE and accept the risk.

Ensure RPE is compatible with other PPE — hard hats, eye protection, and hearing protection. Certain combinations are incompatible; check the RPE manufacturer's guidance.

Air Monitoring and Health Surveillance

Air monitoring is required when COSHH controls are first put in place, when there is reason to suspect exposure may exceed the WEL, and when controls change significantly. Personal air sampling involves the worker wearing a small pump with a filter that captures their actual breathing zone exposure over a shift. Samples are analysed by an accredited occupational hygiene laboratory and results compared to the WEL of 0.1 mg/m³ for RCS.

If monitoring shows exposure is approaching or exceeding the WEL, controls must be improved before work continues. Monitoring results must be kept for 40 years under COSHH Regulation 10 when exposure monitoring is required — the long latency period of silicosis means records must outlast the working lives of those exposed.

Health surveillance under COSHH Regulation 11 is required for workers who are regularly exposed to levels of RCS above the WEL or where there is a residual risk despite controls. Health surveillance for silica exposure means periodic spirometry (lung function testing) by an occupational health provider, plus regular health questionnaires. Workers must be informed of their individual results. If a worker develops signs of silicosis or other occupational lung disease, work arrangements must be reviewed immediately and the worker referred to an occupational physician.

Site Boundary and Neighbour Dust Management

On demolition sites adjacent to sensitive receptors — residential housing, schools, hospitals, care homes — dust must be controlled at the site boundary to protect the public. This requires a boundary dust management plan as part of the Construction Phase Plan.

Boundary controls include: solid hoarding or fencing to reduce wind-driven dust transport; misting systems at demolition face directed to suppress dust before it reaches the boundary; and real-time dust monitors (PM10 or PM2.5 sensors) at the site boundary set to alarm and trigger additional suppression when levels rise.

Action levels for site boundary monitoring are typically set at PM10 150 µg/m³ (action) and 200 µg/m³ (stop work). These are not set by statute for all sites — they are commonly specified in planning conditions or environmental management plans agreed with the local authority. Consult the local planning authority's environmental protection team before starting large demolition projects in built-up areas.

Frequently Asked Questions

Is a standard paper dust mask good enough for demolition?

No. Standard paper masks (FFP1 or FFP2 class) do not provide adequate protection against respirable crystalline silica during demolition of concrete, brick, or mortar. The minimum class for silica work is FFP3, which provides a protection factor of 20. An FFP1 mask has a protection factor of only 4 — it is suitable for nuisance dusts but will not protect against silica at demolition exposure levels. Replace all FFP1 and FFP2 disposable masks with FFP3 on demolition sites where concrete or masonry is being broken. Ensure each mask is individually face-fit tested.

Do we need air monitoring on every demolition job?

Not necessarily on every job, but COSHH Regulation 7 requires you to assess whether exposure is likely to exceed the WEL and to have adequate means to verify that controls are working. For short-duration, infrequent work with good controls in place, a documented risk assessment may be sufficient without personal air sampling. For projects involving significant volumes of concrete or masonry breaking, extended duration, or novel control arrangements, air monitoring should be carried out to validate controls. If in doubt, commission occupational hygiene monitoring — the cost is modest compared to the liability of failing to control silica exposure.

What is a Silica Dust Management Plan and when is it required?

A Silica Dust Management Plan (SDMP) is a written plan, produced specifically for a project or site, that sets out how silica dust exposure will be controlled. It is required by many principal contractors as a condition of starting on site for any work involving substantial silica exposure. It is also required under many local planning consents for demolition projects. An SDMP typically covers: the tasks generating silica exposure; the controls in place (LEV, water suppression, enclosure); the RPE to be used; face-fit testing records; air monitoring programme; health surveillance arrangements; and the responsible person on site. It is distinct from a general COSHH assessment — it is more detailed and site-specific, and typically runs to 4–8 pages for a substantial demolition project.

How often should LEV equipment be inspected?

Under COSHH Regulation 9, LEV must be thoroughly examined and tested at intervals not exceeding 14 months, with records kept for 5 years. In demolition environments, practical site inspection should be much more frequent: vacuums and filter units should be inspected at the start of each shift and after any blockage or impact. H-class filters have a finite capacity — a blocked filter provides negligible dust capture. Set up a daily filter inspection routine, log it, and replace filters proactively rather than reactively. Equally, check that LEV shrouds and hoses are not damaged — a cracked shroud or split hose negates the extraction even if the vacuum unit is working correctly.

Regulations & Standards

• Control of Substances Hazardous to Health Regulations 2002 (SI 2002/2677) — primary COSHH framework

• EH40/2005: Workplace Exposure Limits (4th edition) — sets RCS WEL at 0.1 mg/m³ and RSP WEL at 4 mg/m³

• Construction (Design and Management) Regulations 2015 — Construction Phase Plan to include dust controls

• Health and Safety at Work etc. Act 1974 — general duty to protect health

• HSE INDG463: Dust in the workplace — free guidance leaflet on construction dust

• HSE RR1017: Respirable crystalline silica exposure in construction — detailed research report on exposure levels

• HSE HSG258: Controlling airborne contaminants at work — LEV design and testing guide

• BOHS W401 certificate of competence in asbestos and dust surveying [verify full title]

• BS EN 149:2001+A1:2009 — specification for FFP filtering facepieces

• BS EN 12941 / BS EN 12942 — specification for powered air-purifying respirators (TH3P class)

• BS EN 60335-2-69 — safety requirements for H-class industrial vacuums

• CIBSE TM36 — HVAC system commissioning (for LEV testing methodology)

• HSE — Silica and construction

• HSE — COSHH: A brief guide to the Regulations (INDG136)

• HSE — Dust in the workplace (INDG463)

• HSE — Respiratory protective equipment at work: A practical guide (HSG53)

• BOHS — Dust occupational hygiene guidance

• NFDC — Health and safety guidance for demolition

• pre demolition audit — Pre-demolition survey including COSHH-relevant hazardous materials identification

• selective demolition and strip out — Dust generated during soft strip from plasterboard, floor finishes, and ceilings

• cdm regs demolition projects — CDM Construction Phase Plan requirement for dust management

• demolition waste management — Managing dust-generating waste streams including concrete crushing