COSHH Assessment for Wood Dust: A Practical Guide for UK Tradespeople
Wood dust is one of the most common occupational health hazards in the UK construction and joinery trades — and one of the most underestimated. If you cut, sand, route or machine timber, you are legally required to assess and control that exposure under the Control of Substances Hazardous to Health Regulations 2002 (COSHH). This guide walks you through what a proper COSHH assessment for wood dust actually looks like in practice.
Why Wood Dust Is Classed as Hazardous
Wood dust is not just a nuisance. Prolonged or repeated inhalation can cause:
- Occupational asthma — the airways become permanently sensitised
- Rhinitis and sinusitis — chronic inflammation of the nose and sinuses
- Sino-nasal cancer — hardwood dust (particularly oak and beech) is classified as a Group 1 carcinogen by the International Agency for Research on Cancer
The distinction between hardwood and softwood matters under COSHH. HSE sets a Workplace Exposure Limit (WEL) for wood dust at 1 mg/m³ (8-hour TWA) for hardwoods and 5 mg/m³ for softwoods (mixed loads are treated as hardwood). These limits are published in EH40 — but meeting the WEL is the legal floor, not the target. COSHH requires you to reduce exposure as low as reasonably practicable, even below the WEL.
Who Must Carry Out the Assessment
Under COSHH Regulation 6, employers must carry out a suitable and sufficient assessment before work involving a hazardous substance begins. Self-employed tradespeople have the same duty in relation to themselves and anyone they put at risk. The assessment must be reviewed if working conditions change or there is reason to suspect it is no longer valid.
Step-by-Step: Completing a COSHH Assessment for Wood Dust
1. Identify the substance and the work activity
Be specific. State:
- Type of wood (hardwood, softwood, MDF, OSB — note that MDF contains added resins that create formaldehyde as well as dust)
- The task generating the dust (cross-cutting, sanding, routing, planing)
- Duration and frequency of exposure
- Number of workers exposed
2. Consider who is at risk
Include not just the person operating the machine, but anyone nearby — other trades, labourers, members of the public on site. Some individuals are at greater risk, such as those with pre-existing respiratory conditions.
3. Evaluate exposure
You do not always need air monitoring, but you need a reasonable basis for your judgement. HSE's COSHH Essentials tool and existing workplace monitoring data can help. If work is daily and prolonged (for example, a joinery workshop), formal air sampling by a competent occupational hygienist is advisable.
4. Apply the control hierarchy
This is the heart of the assessment. Controls must follow the hierarchy set out in COSHH Regulation 7:
| Priority | Example for wood dust |
|---|---|
| Eliminate | Specify pre-cut components to avoid on-site cutting |
| Substitute | Use lower-dust sheet materials where the design allows |
| Engineering controls | Local exhaust ventilation (LEV) at source — extraction fitted directly to tools and machines |
| Administrative controls | Rotate workers to limit individual exposure time; restrict access to dusty areas |
| PPE (last resort only) | RPE rated to at least FFP3 for hardwood dust; fit-tested and face-fit recorded |
LEV is the priority control. A well-designed extraction system connected at the tool — whether a floor-standing planer or a site circular saw — will reduce airborne dust dramatically before it reaches the breathing zone. RPE alone is not an acceptable substitute for engineering controls under COSHH.
5. Record your findings
For employers with five or more employees the assessment must be written down, but good practice means recording it regardless. Your COSHH assessment should document:
- The substance and activity
- Who is at risk and why
- The controls selected and why they are proportionate
- Responsible persons for implementing and checking controls
6. Health surveillance
Where there is a reasonable likelihood that workers could develop an occupational disease from wood dust exposure — which for regular woodworking there clearly is — COSHH Regulation 11 requires health surveillance. In practice this typically means a pre-employment respiratory questionnaire and periodic reviews by an occupational health professional. Records must be kept for 40 years.
Common Mistakes to Avoid
- Using a dust mask rated below FFP3 for hardwood dust — FFP1 and FFP2 masks do not provide adequate protection against carcinogenic hardwood dust
- Treating the WEL as a target rather than a maximum ceiling to stay well below
- Ignoring MDF — it generates both wood dust and formaldehyde and needs its own assessment
- Not checking or maintaining LEV — COSHH Regulation 9 requires thorough examination and testing of LEV at least every 14 months, with records kept for five years
- One-size-fits-all assessments — a sanding task in a workshop all day is not the same risk as a single cut on site
Keeping the Assessment Current
A COSHH assessment is a live document. Review it when:
- You change the type of wood or material being used
- Tasks, tools or work locations change significantly
- A worker reports respiratory symptoms
- Health surveillance flags a concern
Wood dust is a well-understood, well-regulated hazard with proven controls. A thorough COSHH assessment is not a bureaucratic exercise — it is the practical tool that keeps your workers' lungs safe over a working lifetime.