How Long is the Short Term Workplace Exposure Limit?

Control of Substances Hazardous to Health (COSHH) is a UK law requiring employers in all industries to prevent or reduce workers’ exposure to certain hazardous substances.

The law regulates workplace exposure limits (WELs) for around 500 hazardous substances. These are legal limits of exposure, measured in concentrations of the hazardous substances in the air (usually mg.m³), averaged over a given timeframe.

COSHH legislation requires that workers are only exposed to a certain amount of a hazardous substance in a specified period of time – the time weighted average (TWA).

What is the Short Term Workplace Exposure Limit?

The short term workplace exposure limit is 15 minutes. A short term exposure limit (STEL) is the concentration to which workers can be exposed continuously to a hazardous substance before it starts to affect their health.

What is the Long Term Workplace Exposure Limit?

The long term exposure limit (LTEL) considers an eight hour reference period. COSHH law requires that the short term exposure limit must take priority over the long term exposure limit.

Short Term vs. Long Term Exposure

The long term exposure limit is there to protect workers from concentrations of harmful substances – the sort of substances which, over an extended period of time, could result in long-term chronic health conditions.

On the other hand, the short term exposure limit is concerned with peak exposure incidents. It’s there to protect workers against immediate ill health effects, whether that’s nausea, dizziness, inflammation, or more serious conditions.

In any case, employers have a legal responsibility to ensure that every employee is not exposed to any concentration of any substance that exceeds the substance’s WELs. And if you run a school, a university or a healthcare establishment, you’ll also have to consider exposure risks for your students, patients, and other visitors.

Exposure Limits in Your Workplace

Many substances will list WEL values on their packaging. However, you must not assume that a substance that does not specify a WEL is necessarily safe to use in all environments for any period of time.

Potentially, all workplaces will make use of hazardous substances with WELs. For example, it’s common to find cleaning products in schools and offices which, if used for too long in a poorly ventilated area, can lead to a range of health problems.

But hazardous substances are so widespread in some sectors that workers may risk excess exposure as a matter of course. In healthcare, for example, employers must meet COSHH exposure regulations for a huge number of substances, including isoflurane, Entonox, formaldehyde, inhalable dust, and a wide range of hazardous chemicals too numerous to mention.

Meeting Your COSHH Obligations

All workers must pay attention to the WELs for every substance they work with. At the same time, you must supply your staff with adequate PPE for each task they undertake, while maintaining an adequate air ventilation system for your workplace.

Yet even with these measures in place, your workforce may still get exposed to dangerous concentrations of hazardous substances. Faulty equipment can lead to a leak. PPE can get damaged or compromised. And a small accident can lead to a substantial chemical spill, the effects of which could last long after the spill’s been cleaned.

But we can help you fulfil your COSHH obligations wherever your staff are exposed to hazardous substances with our bespoke workplace exposure monitoring report. Our comprehensive reports include clear and actionable recommendations, so you’ll know exactly what you’ll have to do to protect your staff.

We specialise in healthcare settings, where we can employ both continuous monitoring and personal sampling processes for operating theatres, endoscopy suites, pathology laboratories, maternity wards, fracture clinics, and more.

Head here to learn more about out workplace exposure monitoring services, and find out how we can help in your department.