What are Workplace Exposure Limits (WELs)?

Workplace Exposure Limits (WELs) relate to the amount of a hazardous substance a person can be safely exposed to while at work. As an employer in an industry where these substances may be present, it’s important to be aware of WELs in order to keep your employees safe.

What type of hazardous substances have WELs?

A hazardous substance can take the form of dust, gases, fumes, chemicals, vapours or biological agents that could cause disease if a person has been exposed to it at dangerous levels.

There are around 500 substances with WELs.  They are published in the Health and Safety Executive’s EH40/2005 Workplace Exposure Limits – and include acetone, carbon monoxide, nitrous oxide and propoxur.

WELs are measured in either parts per million (ppm) for vapours and gaseous materials or by milligrams per cubic metre (mg.m³) for particulate matter.  It should be noted that WELs only consider airborne substances and inhalation as the route of entry into the body.

How can you control exposure to WELs?

To comply with the Control of Substances Hazardous to Health Regulations 2002 (COSHH), exposure must be controlled to levels as low as is reasonably practicable (ALARP).

WELs recognises that some substances can be harmful even with only a brief exposure, whilst others require prolonged exposure.  Therefore, WELs has two reference periods: Long Term Exposure Limit (LTEL) based on an eight-hour time weighted average, and Short Term Exposure Limit (STEL) which applies to any 15-minute period.

In workplace environments where substances with WELs are used, monitoring should be carried out to check that exposure is below the WEL for that particular substance in order to reduce risks. This can be done by measuring the amount of the substance present in the air inhaled by a worker, known as an air sampling survey.

Aegis’ team of health and safety experts is well experienced in helping organisations comply with regulations designed to keep employees safe at work. For more information on how we can help, contact us today.