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.

Dust Levels by Woodworking Task

Not all woodworking tasks produce the same amount of dust. The table below shows typical airborne dust concentrations measured during common operations, based on HSE woodworking research and COSHH Essentials guidance sheets. Compare these figures against the workplace exposure limits: 3 mg/m³ for hardwood dust and 5 mg/m³ for softwood dust.

• Hand sanding: 2–5 mg/m³ (can exceed hardwood WEL of 3 mg/m³)

• Orbital sanding: 5–20 mg/m³ (far exceeds WEL without extraction)

• Circular saw (no extraction): 5–15 mg/m³

• Router (no extraction): 10–40 mg/m³ (highest dust producer of common power tools)

• Planer/thicknesser: 3–10 mg/m³

• CNC machine (enclosed): typically below WEL with proper extraction fitted

The key takeaway: without on-tool extraction, virtually all power tool operations exceed the workplace exposure limit. Even hand sanding hardwood can push exposure above the 3 mg/m³ WEL. Your COSHH assessment must account for the specific tasks performed, not just whether "woodworking" happens on site.

Setting Up Effective Dust Extraction

Dust extraction is not optional where wood dust exposure exceeds the WEL. COSHH Regulation 7 requires employers to prevent or adequately control exposure, and for wood dust, that means local exhaust ventilation (LEV) in most cases. Here is what effective extraction looks like in practice.

• On-tool extraction: Connect an H-class vacuum cleaner directly to the tool's dust port. This captures dust at the point of generation before it becomes airborne.

• Fixed LEV systems: Central extraction systems with ductwork running to each machine are the standard in dedicated workshops. Design these to BS EN 12779 for fixed woodworking extraction systems.

• Capture velocity: The extraction must achieve a minimum of 1 m/s air velocity at the point of dust generation. Lower velocities will not capture the dust effectively.

• Ductwork: Sized correctly for the required airflow rate. Avoid kinks, excessive bends, and long horizontal runs that reduce efficiency. Smooth-bore ducting outperforms flexible hose for fixed installations.

• Filtration: For hardwood dust, use HEPA or equivalent filtration. H-class vacuum cleaners filter 99.995% of particles at 0.3 microns. Vacuum cleaners must comply with BS EN 60335-2-69.

• Maintenance: Empty collection bags before they are half full. Check filters weekly. A full bag or clogged filter dramatically reduces extraction performance.

• LEV testing: COSHH Regulation 9 requires LEV systems to be examined and tested by a competent person at least every 14 months. Test results must be recorded and kept for a minimum of 5 years.

Species-Specific Risks: Which Woods Are Most Dangerous?

Your COSHH assessment should identify the specific wood species being worked with. Different species carry very different risk profiles, and some demand additional control measures beyond standard dust extraction.

• Western red cedar: Causes occupational asthma even at very low exposure levels. It has its own WEL of 0.5 mg/m³, not the standard 3 mg/m³ or 5 mg/m³. Any work with western red cedar requires stringent controls and health surveillance.

• Oak and beech: Carry the highest nasal cancer risk among common hardwoods. Both are classified as Group 1 carcinogens by IARC. Health surveillance is mandatory for workers regularly exposed to these species.

• Iroko: A strong skin and respiratory sensitiser. Workers can develop allergic reactions after repeated exposure, even at concentrations below the WEL.

• MDF (medium-density fibreboard): Releases formaldehyde when cut, adding a chemical exposure risk on top of the dust hazard. Treat MDF as hardwood for dust control purposes and assess formaldehyde exposure separately.

• Treated timber (CCA, tanalised): Releases arsenic, chromium, and copper compounds when cut or sanded. These chemical hazards must be assessed in addition to the wood dust itself.

• Reclaimed timber: May contain lead paint, asbestos contamination, or unknown chemical treatments. Always test or assess reclaimed timber before machining it.

If you cannot identify the wood species, your COSHH assessment must treat it as hardwood and apply the lower 3 mg/m³ workplace exposure limit. This is the only safe default.

Frequently Asked Questions

Is softwood dust dangerous?

Yes. While softwood dust is not classified as a carcinogen like hardwood dust, it is a respiratory sensitiser that causes occupational asthma. The WEL for softwood dust is 5 mg/m³, and health surveillance is recommended for workers regularly exposed.

Do I need extraction on a battery drill making a few holes?

For brief, occasional drilling in wood, the dust exposure is unlikely to exceed the WEL. However, if drilling is a regular part of the work (multiple holes per day), extraction should be provided. Assess the frequency, duration, and whether the wood is hardwood.

Can I use a domestic vacuum cleaner for wood dust?

No. Domestic and commercial vacuum cleaners release fine dust back into the air through their filters. You must use an M-class vacuum (minimum) for softwood, or an H-class vacuum for hardwood and MDF. H-class vacuums filter 99.995% of particles at 0.3 microns.

How do I know if my LEV is working properly?

Your LEV must be tested by a competent person every 14 months under COSHH Regulation 9. Between formal tests, check daily: is the airflow indicator showing correct flow? Are ducts intact with no leaks? Is the collection bag less than half full? Are filters clean?

What about wood dust from composite boards (plywood, chipboard, OSB)?

Composite boards contain adhesive resins that release additional chemical hazards when cut. Plywood and chipboard use urea-formaldehyde, which is classified as a carcinogen. Assess these products for both wood dust and formaldehyde exposure.

Authority Sources and Further Reading

The guidance in this article is drawn from the following authoritative sources. Use these for deeper research or to support your COSHH assessment documentation.

External resources:

• HSE Woodworking Guidance (hse.gov.uk/woodworking)

• HSE COSHH Essentials for wood dust (WD series guidance sheets)

• IARC Monograph Volume 62: Wood Dust

• British Woodworking Federation health and safety resources

• HSE INDG453: Toxic Woods

Related guides on our blog:

• COSHH Regulations UK Complete Guide

• COSHH Assessment for Silica Dust

• COSHH Assessment for Adhesives and Resins

• HAVs Assessment Guide

• What is a RAMS Document?