EH40 workplace exposure limits and how to use the HSE guide
EH40 lists approved workplace exposure limits for Great Britain. Get the HSE PDF, check reference periods and understand its role in COSHH compliance.
EH40/2005 is HSE's publication listing approved workplace exposure limits (WELs) for Great Britain. HSE defines a WEL as a concentration of a hazardous substance in the air, averaged over a set period of time, and says the approved list of those limits is legally binding under COSHH.
Start with the official HSE EH40 PDF. Check HSE's publication page when you download a copy, rather than an old saved file. But meeting a WEL is only part of controlling exposure adequately under COSHH.
Which EH40 edition should you use?
HSE's publication page lists January 2020 for EH40/2005 Workplace exposure limits. It says 13 new or revised limits were introduced from 17 January 2020. The "2005" in the publication reference is not the date of the copy on that page. Check the HSE publication details.
HSE describes EH40 as containing all current GB WELs. It says the list is amended when new or revised limits are approved. Use its current exposure-limits guidance alongside the publication, especially when checking an entry with specific conditions.
COSHH regulation 2 defines a WEL by reference to HSE publication "EH/40 Workplace Exposure Limits 2005", as updated from time to time. The displayed publication date alone does not settle whether a particular limit has changed since then. Read the legal definition of a WEL.
How to read EH40 workplace exposure limits
A workplace exposure limit is an airborne concentration averaged over a specified period. It is not simply an instantaneous reading. HSE's definition makes the averaging period part of the limit.
Use the official table in this order:
- Open the EH40 publication and find the substance you need. Confirm the identity before using a value.
- Read the complete entry. Check its reference period and accompanying notes, rather than copying one number into an assessment. Record the reference period with the value so later comparisons use the same basis.
- Check that the exposure result you want to compare covers the relevant averaging period.
- Consider that comparison within the wider COSHH control requirements. And a result below the limit does not complete the assessment.
Long-term and short-term exposure limits
The usual long-term reference period is eight hours, expressed as a time-weighted average (TWA). The usual short-term reference period is 15 minutes, a short-term exposure limit (STEL). Check the particular entry and its notes: don't assume every short-term entry uses 15 minutes. Use the EH40 table for the applicable period.
An eight-hour comparison and a short-term comparison cover different averaging periods. The HSE definition requires the concentration and reference period to be considered together.
Don't substitute one for the other.
Does being below a WEL mean exposure is safe?
No. COSHH regulation 7 requires employers to prevent exposure or, where prevention is not reasonably practicable, adequately control it. Under regulation 7(7), adequate control requires the Schedule 2A good-practice principles as well as no exceedance of an approved WEL. Read regulation 7.
In specified carcinogenic, mutagenic and occupational-asthma circumstances, exposure must also be reduced to as low a level as is reasonably practicable. A result below a WEL does not remove these duties. Those duties are part of the same COSHH provision.
A missing limit creates another common problem. HSE says only about 500 substances have WELs, although many thousands are used at work. Absence from the list is not evidence of safety. HSE's publication guidance says exposure to all hazardous substances must be prevented or controlled, while its WEL guidance explains the limited coverage of the list.
How are GB limits set and enforced?
HSE says Great Britain is no longer part of the EU limit-setting regime. Its approach includes specialist and economic assessment, independent scientific review, public consultation and HSE Board approval where a new or revised limit is supported. It also considers proportionate control measures rather than relying solely on new limits. HSE sets out its approach here.
A new EU occupational exposure limit does not, by itself, establish a revised GB WEL. Check HSE's GB guidance and the relevant EH40 entry before changing a GB assessment on that basis.
The duties are enforceable under health and safety law. The law provides for improvement notices in the specified circumstances and, where activities involve a risk of serious personal injury, prohibition notices. Contravening a health and safety regulation is an offence. A measurement does not automatically determine a particular notice or penalty.
Does this guidance cover the whole UK?
This guide concerns Great Britain. It does not settle workplace exposure limits for the whole UK. Northern Ireland has separate Control of Substances Hazardous to Health Regulations (Northern Ireland) 2003. Check that jurisdiction before you treat a GB entry as the applicable limit.
RegAffairs AI answers questions about GB workplace exposure limits, with citations to the source documents. Use the official HSE publication to check the applicable table entry and its notes.