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Wood dust – know your limits

19th August 2022
Air Plants dust extraction

Good control of workers’ exposure to wood dust is all about understanding the defined limits in place, and planning adequate measures to minimise exposure.

The current HSE business plan makes lung related illness a priority for 2022/23.  This is important because it means HSE inspectors will be visiting the type of business where there may be a recognised risk of dust or fumes for workers.

Wood processing, including trussed rafter manufacture, is one such sector and we are aware of several TRA members having received recent visits as part of this year’s HSE business inspection programme. Some TRA members have also been asked to complete local authority questionnaires on minimising lung related workplace illness.

Wood dust has defined Workplace Exposure Limits (WEL) meaning TRA members must minimise workers’ exposure to this potential hazard. Softwood dust WEL is at 5mg m3 and as we have explained previously, hardwood dust WEL is now at a lower level of 3mg/m3. These limits are the maximum levels permitted but the ‘As Low As Reasonably Practical’ principle also applies meaning employers need to keep workers’ exposure as low as possible.

HSE inspectors define adequate control of wood dust when:

  • The eight principles of good control practice are applied as set out in Schedule 2A of COSHH;
  • Exposure is below the relevant WEL; and
  • Exposure is reduced to as low a level as is reasonably practicable.
  • Health surveillance is in place.

More detailed information is provided via the HSE website here  and HSE wood Information Sheet WIS 23

The measures to control wood dust will include:

  • Local Exhaust Ventilation (LEV) removing dust at each fixed machine
  • Standalone LEV for mobile or temporary processing equipment
  • Provision of PPE to minimise residual exposure
  • Good workplace practice to minimise dust e.g. vacuum not sweeping

Joe Smith, group health and safety manager at Thomas Armstrong said:

“Wood dust is a key hazard in our industry and it has to be managed well. For us, the starting point was a well specified and installed LEV system. Getting this right means we can operate from the position of already being significantly below the WEL. This allows us the opportunity to look for further small improvements whilst protecting our employees from the hazard.”

Most TRA members are only processing TR26 and C24 softwood and so their LEV equipment can operate to the softwood WEL of 5mg m3. However, where members are also processing hardwoods such as oak for exposed trusses or cutting hardwood plywood, LEV must be provided operating at the lower limit of 3mg m3.  This could be separate LEV for the hardwood processing equipment or companywide LEV all of which operates at this lower level.

Thanks to Air Plants for the use of their image. To see more information about LEV equipment visit

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Trussed Rafter Association