Dust Control on Site: RPE, LEV, Wet Cutting & COSHH Requirements

Summary

Construction dust is one of the most underestimated occupational health hazards in the UK building industry. An estimated 13,000 construction workers die each year in the UK from occupational lung disease, and many thousands more are diagnosed with conditions including silicosis, asbestosis, COPD, and occupational asthma linked to workplace dust exposure. The damage is cumulative, often invisible for years, and irreversible.

Three types of construction dust cause the most serious harm: silica dust (from cutting, grinding, or drilling concrete, stone, brick, and mortar), wood dust (from hardwood and softwood cutting, sanding, and routing — hardwood dust is a known carcinogen), and asbestos dust (see asbestos). All three are subject to specific Workplace Exposure Limits (WELs) under COSHH Regulations.

The hierarchy of dust control follows the standard COSHH hierarchy: eliminate the dust (e.g. choose a non-cutting method); substitute with a less dusty process; enclose or extract at source (LEV — local exhaust ventilation, on-tool extraction); and only then use RPE as the final layer of protection. A dust mask alone is not dust control — it is the last resort, and only effective if it is the right specification and worn correctly.

Key Facts

• Legal basis: Control of Substances Hazardous to Health Regulations 2002 (COSHH)
• WEL for silica (respirable): 0.1 mg/m³ (8-hour TWA) — the most stringent construction WEL for a common dust
• WEL for hardwood dust (mixed): 3 mg/m³ (8-hour TWA) — classified as a carcinogen
• WEL for softwood dust: 5 mg/m³ (8-hour TWA) — still hazardous; softwood dust causes occupational asthma
• WEL for general inhalable dust: 10 mg/m³ (8-hour TWA) — non-specific dusts
• WEL for respirable dust (general): 4 mg/m³ (8-hour TWA)
• Silicosis: Incurable fibrotic lung disease caused by silica dust; even short exposures to very high concentrations can cause acute silicosis; chronic silicosis results from years of lower-level exposure
• Silica-containing materials: Concrete, mortar, brick, stone (sandstone, slate, granite), engineered stone, ceramic tiles — approximately 30% of concrete and mortar is silica
• Engineered stone (quartz worktops): Approximately 90–95% silica by composition — extremely high silica dust risk when cutting; cases of accelerated silicosis have occurred in UK kitchen fitters
• Wet cutting: Using water at the blade/disc eliminates airborne dust at source — effective and simple; reduces silica exposure by approximately 90%
• On-tool extraction (LEV): Angle grinder or saw fitted with a vacuum extraction hood captures dust at the point of generation; M-class or H-class vacuum required for silica and wood dust
• M-class vacuum: Captures particles to 0.01% penetration — suitable for softwood, most construction dusts
• H-class vacuum: Captures to 0.005% penetration — required for hardwood dust, silica (in some situations), and asbestos work
• RPE for silica: Minimum FFP3 disposable respirator; powered air-purifying respirator (PAPR) or half-face with P3 filter preferred for longer exposures
• FFP1: Does NOT provide adequate protection against silica or wood dust — do not use for cutting or grinding
• Face fit test: Any tight-fitting RPE (FFP3, half-face, full-face) requires a face fit test to confirm the seal — beards break the seal
• COSHH assessment: Required before using any substance that may be hazardous to health — dust is a substance under COSHH

Quick Reference Table

Detailed Guidance

COSHH Assessment for Dust

Before starting any work that generates dust, a COSHH assessment is required. For common construction tasks, the HSE provides COSHH essentials guidance and a risk assessment tool online. The assessment must cover:

1. What substance or dust is involved
2. What harm can it cause (silicosis, asthma, cancer)
3. What controls will be used (wet cutting, LEV, RPE)
4. Emergency procedures (spill, injury)
5. Monitoring and health surveillance requirements

Health surveillance: COSHH Regulation 11 requires health surveillance where workers are regularly exposed to significant quantities of dust that causes occupational disease. In practice, this means regular chest X-rays or lung function tests for workers regularly exposed to silica or hardwood dust — not just a paper exercise.

Wet Cutting

Wet cutting is the most effective single control for silica dust. Water is applied at the blade to suppress dust at the point of generation. Most angle grinders, disc cutters, and floor saws can be fitted with a water supply adapter.

How to set up wet cutting:

• Use a dedicated water hose or purpose-designed water tank/pump attachment
• The water flow must be continuous and directed at the cutting point — not just dampening the surface
• Use approximately 1–2 litres per minute at the blade
• Water does not eliminate silica dust entirely but reduces airborne respirable silica by approximately 90%
• Even with wet cutting, RPE (FFP3 minimum) should still be worn for sustained cutting work
• Ensure water slurry is disposed of correctly — do not allow silica-laden slurry to run into drains

On-Tool Extraction (LEV)

On-tool local exhaust ventilation captures dust at the source. For angle grinders, circular saws, routers, and belt sanders, purpose-designed shrouds and hoods connect the tool to an extraction vacuum.

Requirements:

• The extraction vacuum must be of appropriate class — M-class minimum for most dusts, H-class for hardwood and silica
• The connection between the tool and the vacuum must be airtight — poor connections allow dust to escape
• Empty the vacuum regularly (at least daily) — do not overfill, as full vacuums lose suction and filtration efficiency
• When changing vacuum bags or filters, do not create secondary dust exposure — wear RPE when emptying

Fixed LEV systems (for workshop environments):

• A ducted extraction system connected to a dust filter unit provides continuous extraction for fixed machines (table saw, bench planer, band saw)
• Must be designed to achieve the required capture velocity at each tool
• Must be inspected and tested every 14 months under COSHH Regulation 9

RPE Selection and Use

Face fit testing: Any tight-fitting RPE (FFP2/FFP3 disposables, half-face masks, full-face masks) must be face-fit tested for the specific wearer using the specific make and model of RPE. A face fit test checks that the face seal is effective. Key points:

• Beards break the face seal — workers cannot wear tight-fitting RPE if they have a beard
• Glasses may affect the seal — test with the glasses being worn
• Different makes and models fit differently — fit test to the specific product
• Fit test records must be kept

Wearing disposable respirators correctly:

• Mould the nose clip over the bridge of the nose — essential for a seal
• Perform a positive and negative pressure check before entering the work area
• Replace when breathing resistance increases noticeably, when the mask is visibly dirty, or after each working day maximum
• Never re-use a disposable respirator after washing — the filtration structure is destroyed

Powered air-purifying respirators (PAPRs):

• A battery-powered unit provides a continuous flow of filtered air over the face — creates a positive pressure, so minor beard/face fit issues are tolerated
• Appropriate protection factor: TH2 (APF 20) or TH3 (APF 500) depending on filter
• Particularly useful for sustained dusty work (stone cutting, hardwood workshop)
• Battery life must be managed — check charge before starting; recharge during breaks

Wood Dust — Specific Considerations

Wood dust is covered by COSHH but often overlooked on site because sawing timber seems less hazardous than cutting concrete. Key facts:

Hardwood dust is a Group 1 carcinogen — it causes nasal and sinonasal cancer (cancer of the nose and sinuses). The cancer typically develops after years of exposure and appears 20–30 years after the exposure period. Exposure limits are set to minimise but not eliminate the risk.

Softwood dust (pine, spruce, larch) causes occupational asthma — again cumulative, after repeated exposure. Carpenters and joiners have higher rates of occupational asthma than the general population.

Controls for wood dust:

• On-tool extraction is the primary control — almost all woodworking tools have an extraction port
• Use M-class or H-class vacuum for hardwoods
• RPE: FFP2 minimum for softwood; FFP3 for hardwood
• Keep the work area clean — do not allow wood dust to accumulate on floors and surfaces; this becomes re-suspended when people walk through

Composite wood products (MDF, OSB, chipboard): MDF generates large quantities of fine dust and also contains formaldehyde-based binders — additional COSHH hazard. Use on-tool extraction and FFP3 RPE when cutting MDF.

Site Dust Control Plan

For any project involving significant dust exposure, a simple Dust Control Plan is good practice and evidence of COSHH compliance:

1. What materials generate dust: List all dusty operations (cutting concrete, sawing hardwood, sanding walls)
2. Controls at source: Wet cutting, on-tool extraction, task scheduling (wet operations first)
3. RPE: Type, class, face-fit test status of each operative
4. Enclosure: Polythene sheeting to isolate dusty areas from clean areas and occupied spaces
5. Cleaning: Vacuum (not sweep) dust from surfaces; use damp mopping
6. Waste disposal: Collect and bag silica slurry and wood dust; dispose as hazardous waste if contaminated with asbestos or other chemicals
7. Health surveillance: For regular workers

Frequently Asked Questions

Is a standard dust mask enough for cutting concrete?

No. A standard dust mask or paper face mask (typically FFP1 or unrated) does not provide adequate protection against respirable silica dust. The particles that cause silicosis are invisible to the naked eye — they pass straight through inadequate RPE and deposit in the lung tissue. FFP3 is the minimum for silica; powered air-purifying respirators (PAPRs) are better for extended cutting work.

I'm cutting engineered stone worktops (quartz) for a kitchen — what do I need?

Engineered quartz surfaces contain 90–95% crystalline silica — the highest silica content of any common construction material. Cutting quartz has caused acute silicosis (severe disease developing within weeks or months) in UK kitchen fitters. Requirements are: wet cutting at all times, on-tool extraction with H-class vacuum, FFP3 or PAPR, restrict access to the work area, clean up slurry correctly. Do not dry cut quartz under any circumstances.

Do I need to control dust when working in an occupied home?

Yes — your duty extends to non-employees including occupants. Dust should be contained using polythene sheeting or temporary enclosures. Inform the customer to vacate the area during dusty operations. Vacuum clean (not sweep) between work sessions. In homes with vulnerable people (children, elderly, people with respiratory conditions), extra precautions are warranted.

How often should I replace the filters in my on-tool extraction vacuum?

Follow the manufacturer's guidance — typically replace filters at a set number of hours of use or when performance (suction) drops. For M-class and H-class vacuums, do not try to clean or re-use paper filters — they are single-use. For H-class vacuums, fit a pre-filter (separator) upstream of the main filter to extend filter life.

Does wet cutting eliminate the need for RPE?

No — wet cutting reduces but does not eliminate airborne silica. Even with wet cutting, some dust becomes airborne at the cutting point. PPE (FFP3 minimum) should still be worn when using wet cutting for sustained operations. The combination of wet cutting plus on-tool extraction plus RPE provides defence in depth.

Regulations & Standards

• Control of Substances Hazardous to Health Regulations 2002 (COSHH) — primary legislation; includes dust

• EH40/2005 Workplace Exposure Limits (HSE) — current WELs including silica, wood dust — updated periodically

• HSE Guidance Note EH44 (Dust in the workplace: general principles of protection) — practical COSHH guidance for dust

• BS EN 149 (Respiratory protective devices — filtering half masks to protect against particles) — FFP1/2/3 standard

• BS EN 12941 (Powered filtering devices incorporating a helmet or hood) — PAPR standard

• HSE — Dust Control in Construction — Official guidance, COSHH essentials

• HSE — EH40 Workplace Exposure Limits — Current WEL values

• BOHS — Breathe Freely Campaign — Occupational lung disease prevention in construction

• HSE — Silica Alert — Silicosis specific guidance and case studies

• asbestos — Asbestos dust — separate and more severe hazard

• manual handling — Complete risk assessment picture alongside dust

• cdm regulations — COSHH assessment as part of CDM Construction Phase Plan

• large format tiles — Cutting porcelain tile dust — silica content

• natural stone — Natural stone cutting — silica dust risk