COSHH Regulation and Duties

Workplace Exposure Limits Explained

What Workplace Exposure Limits and EH40 Mean for Hospitality

Quick answer

A workplace exposure limit, usually shortened to WEL, is the maximum concentration of a hazardous substance in the air that staff can be exposed to, averaged over a set period. The limits are published by the HSE in a document called EH40, and they form part of the legal framework under COSHH. For most hospitality businesses, airborne exposure is low and well within any limit, but the concept still matters: a few substances used in kitchens, bars, and bakeries do have limits, and understanding them tells you when ordinary controls are enough and when you need to think harder. This article explains what workplace exposure limits are, where EH40 fits, and which substances are worth attention.

A workplace exposure limit is the maximum airborne concentration of a substance, given as eight-hour and fifteen-minute averages.
Limits sit under COSHH and are published by the HSE in EH40, which is the master list referenced by safety data sheets.
A WEL is a ceiling, not a safe line; you must still reduce exposure as far as is reasonably practicable.

Key takeaways

A workplace exposure limit is the maximum airborne concentration of a substance, given as eight-hour and fifteen-minute averages.

Limits sit under COSHH and are published by the HSE in EH40, which is the master list referenced by safety data sheets.

A WEL is a ceiling, not a safe line; you must still reduce exposure as far as is reasonably practicable.

Flour dust, carbon dioxide, and some cleaning chemical vapours are the hospitality substances most likely to have relevant limits.

If exposure could approach a limit, you may need ventilation, changed working methods, or air monitoring to stay below it.

What a Workplace Exposure Limit Actually Is

A workplace exposure limit is a concentration of a substance in air that should not normally be exceeded. Limits are given as two time-weighted averages: a long-term limit averaged over eight hours, which protects against effects that build up over a working day, and a short-term limit averaged over fifteen minutes, which protects against the effects of brief high exposures. The limits sit under COSHH, which requires that exposure to substances with a WEL is controlled so it stays below the limit. The HSE publishes all the assigned limits in EH40, its list of workplace exposure limits, which is updated periodically. A WEL is not a safe-or-unsafe line on its own; the duty under COSHH is still to reduce exposure as far as is reasonably practicable, with the limit acting as a ceiling that must not be crossed.

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The EH40 List and How It Is Used

EH40 is the HSE publication that lists every substance with an assigned workplace exposure limit, together with the long-term and short-term figures. When you read a safety data sheet, Section 8 will reference any applicable exposure limit, and EH40 is the master source behind it. For a hospitality operator, EH40 is rarely something you read cover to cover. The practical use is to check, when a safety data sheet mentions a limit, what that limit is and whether your way of working could realistically approach it. In the vast majority of kitchen and bar tasks the answer is clearly no, because the quantities are small and the work is intermittent. EH40 becomes more relevant where a substance is used in volume, in an enclosed space, or in a way that puts a meaningful amount into the air.

Which Hospitality Substances Have Limits

Several substances found in hospitality carry workplace exposure limits worth knowing about. Flour dust has a long-standing WEL and matters in bakeries and any kitchen doing significant flour handling, where it is a recognised cause of occupational asthma. Carbon dioxide, used in cellars and for drinks dispense, has a limit and can build up dangerously in poorly ventilated cellars, which is why ventilation and gas alarms matter there. Cleaning chemicals can release vapours such as ammonia or chlorine-based gases, particularly if products are mixed, and these have limits too. For most sites, normal dilution, good ventilation, and never mixing products keep exposure far below any limit. The value of knowing which substances have limits is that it points you to the few situations where airborne exposure is a real consideration rather than a theoretical one.

When Exposure Limits Mean You Must Do More

If your assessment suggests exposure could approach a workplace exposure limit, ordinary controls are no longer enough on their own. You may need engineering controls such as local exhaust ventilation, changes to how the work is done, and in some cases air monitoring to confirm that exposure stays below the limit. A bakery with heavy flour handling, or a cellar where carbon dioxide could accumulate, are the realistic hospitality examples. The practical trigger is simple: if you cannot be confident from the way the work is done that exposure is comfortably below the limit, you should either change the work to reduce it or monitor to prove it. This is where COSHH moves from paperwork into active management, and it is exactly the situation where specialist advice can be worth the cost.

What to do next

Check Section 8 of each safety data sheet for a limit

Note any product that references a workplace exposure limit so you can judge whether your use could approach it.

Protect against flour dust and cellar gas specifically

Control flour dust at source in bakeries and ventilate cellars where carbon dioxide can build up, since both carry meaningful limits.

Never mix cleaning chemicals

Mixing products such as bleach and acidic cleaners can release hazardous gases that approach or exceed exposure limits quickly.

Common mistakes to avoid

Mistake

Treating a workplace exposure limit as a safe target

Instead

A WEL is a ceiling that must not be crossed, not a level to aim for. COSHH still requires you to reduce exposure as far as is reasonably practicable below the limit.

Mistake

Ignoring carbon dioxide build-up in cellars

Instead

Carbon dioxide has a workplace exposure limit and can accumulate in confined cellars. Ventilation and gas detection are needed where it is used or stored.

Frequently asked questions

What is a workplace exposure limit?

It is the maximum concentration of a hazardous substance allowed in workplace air, expressed as a long-term average over eight hours and a short-term average over fifteen minutes. The limits are set under COSHH and listed by the HSE in EH40.

What is EH40?

EH40 is the HSE publication that lists all assigned workplace exposure limits in Great Britain, with the long-term and short-term figures for each substance. Safety data sheets reference it in Section 8 where a limit applies.

Do exposure limits apply to most hospitality work?

For most kitchen and bar tasks, exposure is far below any limit because quantities are small and work is intermittent. Limits become relevant for flour dust in bakeries, carbon dioxide in cellars, and cleaning chemical vapours, especially if products are mixed.

COSHH Regulation and Duties