Hazardous substances

What you need to know

The Control of Substances Hazardous to Health Regulations (COSHH) requires employers to ensure that the exposure of employees to substances that are hazardous to health is either prevented or, where this is not reasonably practicable, adequately controlled.

These web pages provide guidance on the most common hazardous substances found in the woodworking industry.

Hardwood dust can cause a rare form of nasal cancer. As well as causing asthma, wood dust, sap and the lichens associated with wood can have adverse health effects on the skin, respiratory tract (nose and lungs), eyes as well as the whole body.

Some chemicals used in the woodworking industries, such as solvent based stains, varnishes, paints and adhesives, as well as those in wood preservatives and industrial treatment plants, can have serious effects on the liver, kidneys and central nervous system.

The Table shows some of the main substances that can cause health risks as well as the controls you may need. Particular care should be taken when using dichloromethane (DCM), also known as methylene chloride, a solvent used to strip paint from wood. As well as being classed as a carcinogen, the vapour can cause drowsiness and headaches. In high concentrations, this can lead to unconsciousness and death. At present DCM can only be used for paint, varnish or lacquer stripping in industrial premises where appropriate safety measures are used.

Wood dust


Hardwood, softwood and wood composites - chipboard, medium density fibreboard (MDF) etc.

Health risk

  • Can cause asthma.
  • May cause dermatitis
  • Hardwood dust can cause a rare form of nasal cancer

Controls to consider

  • Substitute high risk woods that may cause asthma. These include some hardwoods and softwoods such as Western Red Cedar. Use dust extraction. Use vacuum equipment that meets at least the dust class M (medium hazard) classification for cleaning.
  • RPE with a minimum assigned protection factor of 20 (eg FFP3) will be required for most machining operations and for short duration dusty tasks such as emptying LEV dust collectors.
  • If RPE is required for high work rate activities or extended wear times then powered RPE may be more suitable.
  • There is further information on RPE for protection against wood dust is available here: Selecting suitable respiratory protective equipment



  • Varnish
  • Paint
  • Thinners
  • Adhesive
  • Paint stripper
  • Stain
  • Wood preservative

Health risk       

  • Liver or kidney damage
  • Central nervous system effects
  • Dermatitis

Controls to consider

Select safer material like waterborne products. Use extraction ventilation. You may also need RPE. Use air fed RPE (breathing apparatus) in restricted spaces. Use a high efficiency spray gun. Provide protective clothing including protective gloves. Provide good general ventilation. Provide good washing facilities and skin creams.

Reactive systems


  • Isocyanate based products, eg 2pack (2K) paints, varnishes and adhesives
  • Epoxy systems

Health risk

  • Isocyanate – asthma and dermatitis
  • Epoxy – dermatitis

Controls to consider

  • Spray in an enclosed spray booth or room with extraction.
  • Use air fed RPE, protective clothing and gloves for spraying.
  • Use protective gloves and clothing for brush and roller application.
  • Provide good washing facilities and skin creams.

Wood preservatives


Solvent or water borne products

Health risk

  • Damage to central nervous system
  • Dermatitis

Controls to consider

  • Cut out and replace diseased timbers. Kill disease by drying out.
  • Use breathing apparatus in confined spaces.
  • Provide good washing facilities.

How can I protect my employees?

Use the information in the Table and your product safety data sheets to assess all work activities that may expose employees to any hazardous substances (this is your 'COSHH assessment'). Remember to involve your employees in your assessment. This helps you cover all the risks for the tasks they actually carry out, and increases the chance that they will use the necessary control measures. Don't forget to assess the risks involved in maintenance and cleaning tasks.

Always try to prevent exposure to a hazardous substance at source. You can:

  • avoid using it, for example, use a water-based rather than solvent-based products;
  • use a safer process such as a vacuum cleaner rather than a brush to clean up wood dust.

If you can't prevent exposure, you need to control it adequately. For wood dust, use fixed local exhaust ventilation (LEV) that will effectively control the dust at source as it is produced.

Respiratory Protective Equipment (RPE) may be required but is no substitute for controlling the hazardous substance at source and you should only use it as additional protection. For example, you might need to use respirators (and other personal protection) as a temporary measure where engineering controls are being developed and/or modified. They may also be needed for short-term jobs such as cleaning and maintenance that produce high levels.

HSE's COSHH website gives you information on what the law requires and advice on completing COSHH assessments. See also COSHH and Woodworkers key messages.

COSHH Health surveillance collects information to protect employees' health by the early detection of adverse effects caused by exposure to hazardous substances. It is not a substitute for preventing or adequately controlling exposure, but it ensures that any adverse effect is detected at the earliest stage. It can also help in evaluating the effectiveness of the control measures detailed in the COSHH assessment. Sample questionnaires for wood dust health surveillance can be found on the wood dust page.

The main health risk is occupational asthma caused by inhalation of wood dust. Substances such as wood dusts and resins, solvents, paints, varnishes and strong detergents however, will also damage the skin. This may lead to skin soreness, blotches, cracking, itching and blisters. These are signs of irritant and allergic dermatitis. Most solvents can be absorbed through the skin and they can also pass through gloves if they are the wrong type. Choosing the right gloves is therefore important. If gloves get contaminated inside they should be thrown away. If you use latex gloves, provide 'low-protein powder-free' gloves. Train employees to examine skin for any unusual signs that might indicate exposure and to report any concerns to a responsible person.  

Biological monitoring techniques are available for some particular chemical substances used in woodworking (eg isocyanates, epoxy systems) and they can be used to determine whether employees are being occupationally exposed to those substances.

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Updated 2021-09-30