Workplace Exposure Limits: After Brexit and Beyond

workplace exposure limits

What are workplace exposure limits? As defined by the Health and Safety Executive, “WELs are GB occupational exposure limits approved by HSE. They are set to help protect workers’ health. WELs are concentrations of hazardous substances in the air, averaged over a set period of time.”

Workplace Exposure Limits (WELs) which had not been implemented before Brexit, are no longer to be implemented automatically as originally planned.

The WEL for hardwood dust was due to be lowered from 3mg/m3 to 2mg/m3 in January 2023. However, the UK will not be reducing the WEL for hardwood dust just yet.

The HSE, though, is developing a process for introducing new/revised WELs that may introduce limits that depart from European requirements.  The HSE’s approach will include the following:

  • Specialist assessment and analysis of substances to which anyone may be exposed, including an economic assessment considering how much each substance is used in the UK and the economic impact on the business of additional controls or alternatives,
  • the Workplace Expert Health Committee (WEHC) being used as independent experts to review the scientific basis for any WEL proposed,
  • a public consultation on the updates prior to implementation, and,
  • approval from the HSE Board prior to implementation.

WELs for use with the Control of Substances Hazardous to Health Regulations 2002 (as amended) (COSHH) is defined for some materials and are published in EH40/2005. Workplace Exposure Limits may be accessed via this link: EH40/2005 Workplace exposure limits (

For those affected by WELs, remember they should not be thought of as ‘targets’ or ‘safe’ limits for exposure to substances. Instead, and as required by COSHH, the employer should implement control measures following the ‘Principles of good practice for the control of substances hazardous to health.’

These include measures such as:

  • reducing the emission of a contaminant at the source, rather than developing ways of removing the contaminant from the workplace once it has been released and dispersed,
  • considering all possible routes of exposure – inhalation, ingestion and skin exposure,
  • using control measures that are proportionate to the risk which takes into account the severity of the hazard and the magnitude, frequency and duration of exposure, and;
  • Checking and regularly reviewing all elements of control measures for their continuing effectiveness.

Further detail on the Principles of Good Practice  are detailed in Schedule 2A of the COSHH Regulations which, together with the accompanying Approved Code of Practice, may be downloaded here:

Control of substances hazardous to health (COSHH). The Control of Substances Hazardous to Health Regulations 2002 (as amended). Approved Code of Practice and guidance L5 (

If you would like any advice on Workplace Exposure Limits or anything else you have read here, please contact worker health specialist Morag McWilliam at [email protected].

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