• International Workplace
  • 19 December 2017

Consultation on implementing new and revised Workplace Exposure Limits

The Health and Safety Executive (HSE) is consulting on the implementation of new and revised Indicative Occupational Exposure Limit Values (IOELVs) for 31 chemical substances to help protect workers from the ill health effects of exposure to hazardous substances in the workplace.

The consultative document sets out HSE’s proposals for establishing workplace exposure limits for the substances listed in the fourth Indicative Occupational Exposure Limit Values (IOELVs) Directive 2017/164/EU, in order to implement it in Great Britain. The Directive introduces new, or revised, exposure limits for 31 substances.

The fourth IOELV Directive was adopted by the Commission on 31 January 2017.

In 2005, the then Health and Safety Commission introduced a new framework for setting occupational exposure limits (OELs) following an amendment to the Control of Substances Hazardous to Health (COSHH) Regulations 2002 (S.I. 2004 No. 3386).  The new system dispensed with the previous system of Maximum Exposure Limits (MELs) and Occupational Exposure Standards (OESs) and replaced both with a single type of limit, the Workplace Exposure Limit or WEL.

The requirements for compliance with WELs are set out in Regulation 7(7) of the COSHH Regulations 2002 (as amended). In essence, the emphasis in the WEL system is on the need to control exposure to substances according to the principles of good practice. In addition to these general principles of good practice, control advice sheets laying out step-by-step instructions for specific tasks and processes are available via the electronic system of COSHH Essentials (  These control guidance sheets represent good practice for the control of hazardous substances.

It is a legal requirement that the WEL should not be exceeded. A WEL is defined as the concentration of a hazardous substance in the air that people breathe, averaged over a specified reference period referred to as a time-weighted average (TWA).  Two periods are used: long-term exposure limit (eight hours) and short-term exposure limit (STEL) (15 minutes).

WELs are published in the HSE publication EH40 Workplace Exposure Limits, available on the HSE website at:

The consultation on implementing new and revised Workplace Exposure Limits began on 10 November 2017 and ends on 2 February 2018. The document is available to download here.