COSHH Assessment for Wood Dust: Hardwood, Softwood and MDF Guide

Why Wood Dust is a Serious Health Hazard

Wood dust is not just a nuisance. It is a confirmed cause of cancer. The International Agency for Research on Cancer (IARC) classifies hardwood dust as a Group 1 carcinogen, meaning there is sufficient evidence that it causes cancer in humans. Specifically, hardwood dust causes adenocarcinoma of the nasal cavity and paranasal sinuses.

Softwood dust is not classified as a carcinogen, but it is a potent respiratory sensitiser. It causes occupational asthma, and once sensitised, even low exposures can trigger severe symptoms. Over 3,500 woodworkers develop occupational asthma each year in the UK.

MDF (medium-density fibreboard) presents a dual hazard. Cutting, routing or sanding MDF releases very fine wood dust particles and formaldehyde vapour. Formaldehyde is also classified as a Group 1 carcinogen. Any COSHH assessment involving MDF must address both hazards.

Workplace Exposure Limits for Wood Dust

The workplace exposure limits (WELs) for wood dust are published in EH40 (Table 1) by the Health and Safety Executive. These are legal limits, not guidelines.

• Hardwood dust: 3 mg/m³ (8-hour TWA, inhalable fraction)
• Softwood dust: 5 mg/m³ (8-hour TWA, inhalable fraction)
• Mixed dust (hardwood + softwood): 3 mg/m³ applies. When both species are present, the lower hardwood limit takes precedence.
• Formaldehyde (from MDF): 2 ppm WEL (8-hour TWA), with a short-term exposure limit (STEL) of 2.5 ppm.

Important: If you cannot identify the wood species, treat it as hardwood and apply the 3 mg/m³ limit. This is the safe default and what HSE inspectors will expect.

Step-by-Step COSHH Assessment for Wood Dust

A COSHH assessment for wood dust follows the same structure as any COSHH assessment, but you need substance-specific detail. Here is how to work through it.

Step 1: Identify the Wood Species and Products

List every type of wood and wood-based product used on site. Common hardwoods include oak, beech, ash, mahogany, walnut and iroko. Common softwoods include pine, spruce, cedar and larch. Engineered products like MDF, plywood, chipboard and OSB each have their own risk profile because of the resins and adhesives they contain.

Check the safety data sheets (SDS) for any engineered board products. These will tell you what resins are used and whether formaldehyde is a concern.

Step 2: Identify Dusty Tasks

Not all woodworking tasks produce the same amount of dust. The highest exposure tasks are:

• Sanding (especially belt and orbital sanding, which produces very fine dust)
• Routing and profiling
• Sawing (circular saws, mitre saws, table saws)
• Planing and thicknessing
• Drilling (especially dowelling and morticing)
• Sweeping up dust and debris (often the most overlooked exposure)

Step 3: Who is Exposed

Think beyond the person holding the saw. Wood dust travels. People who may be exposed include:

• Carpenters and joiners doing the cutting
• Kitchen fitters and shop fitters working with MDF
• Labourers and site cleaners sweeping up
• Other trades working nearby in shared spaces

Step 4: Control Measures

Because hardwood dust is a carcinogen, COSHH Regulation 7 requires you to reduce exposure as far as is reasonably practicable and then to below the WEL. RPE alone is not acceptable as a primary control. You must use engineering controls first.

On-tool extraction. Every power tool that generates wood dust must have local exhaust ventilation (LEV) connected to it. This is not optional. It is a legal requirement under COSHH for carcinogenic substances. For portable tools on site, this means a dust extraction unit connected directly to the tool's dust port.

Fixed extraction systems. In workshops, fixed dust extraction systems should be designed and installed to BS EN 12779. Each machine needs a dedicated extraction point with sufficient air velocity to capture dust at source.

Vacuum cleaning. Use an H-class vacuum for cleaning up wood dust. M-class vacuums are NOT sufficient for carcinogenic dust. H-class vacuums have HEPA filtration and are tested to capture 99.995% of particles. Never use a standard workshop vacuum or a broom.

RPE (respiratory protective equipment). RPE is a secondary control, used alongside extraction. For softwood dust, FFP2 disposable masks are the minimum standard. For hardwood or MDF dust, you need FFP3 protection. All RPE must be face-fit tested. Tight-fitting masks will not work with beards.

Never use compressed air to blow down. Using compressed air to clean wood dust off workpieces, clothing or benches is prohibited under COSHH. It disperses fine dust into the air and massively increases everyone's exposure. This is a common enforcement action by HSE inspectors.

Step 5: Health Surveillance

Health surveillance is a legal requirement under COSHH Regulation 11 for workers regularly exposed to hardwood dust or any wood dust that causes asthma. This is not discretionary.

• Baseline health questionnaire before the worker starts exposure
• Lung function test (spirometry) as a baseline
• Annual review by an occupational health professional
• Workers must report persistent nasal symptoms (stuffiness, nosebleeds, loss of smell) immediately, as these can be early signs of nasal cancer

Health surveillance records must be kept for 40 years (because of the cancer risk). This is longer than the standard 5-year retention period.

Step 6: LEV Testing

Under COSHH Regulation 9, all local exhaust ventilation systems must be thoroughly examined and tested at least every 14 months. This applies to both fixed workshop extraction and portable on-tool extraction units.

• Testing must be carried out by a competent person (usually a specialist LEV engineer)
• Test records must be kept for at least 5 years
• This is a statutory duty. Failure to test LEV is one of the most common COSHH enforcement actions in the woodworking sector

MDF: The Hidden Risk

MDF deserves special attention in any wood dust COSHH assessment. Standard MDF contains urea-formaldehyde resin, typically 8-14% by weight. When you cut, rout or sand MDF, you release both very fine wood dust particles and formaldehyde vapour.

This means your COSHH assessment for MDF must address two separate hazards: the wood dust itself (assessed against the 3 mg/m³ hardwood WEL, since MDF particles are too fine to distinguish from hardwood) and formaldehyde vapour (assessed against the 2 ppm WEL).

On-tool extraction is essential when working with MDF. RPE alone will not adequately protect against formaldehyde vapour unless you are using a mask with a combination particulate and formaldehyde filter (an A2P3 filter). A standard FFP3 dust mask does not filter formaldehyde gas.

Where possible, consider substituting MDF with lower-emission alternatives. Some manufacturers produce low-formaldehyde MDF, though this does not eliminate the wood dust hazard.

Generate Your Wood Dust COSHH Assessment

Writing a COSHH assessment from scratch takes time, especially when you need to look up substance-specific WELs, match control measures to the hazard, and get the regulatory references right. SwiftRMS generates COSHH assessments with substance-specific exposure limits, control hierarchies, and health surveillance requirements built in. You describe the task and the substances, and the system produces a structured, regulation-compliant document. Learn more about COSHH assessments or try it free.

Related Guides

If you found this guide useful, you may also want to read our COSHH Regulations UK guide for a broader overview of the regulations. For another high-risk substance, see our COSHH assessment for silica dust. And if you need to pair your COSHH assessment with a safe system of work, our guide on how to write a method statement covers that process step by step.