Project Description

Workplace Exposure Limits Explained

All businesses have a duty to prioritise the health and wellbeing of their employees. This is especially the case in occupations where staff are likely to be exposed to hazardous substances, such as chemicals, gases and fumes.

Workplace Exposure Limits (WELs) are restrictions that are set under COSHH (Control of Substances Hazardous to Health) regulations in order to ensure that companies throughout the UK take the necessary precautions to prevent their workers from being dangerously exposed to harmful substances, specifically through inhalation.

In this guide, we’ll provide a detailed explanation of WELs, associated regulations, and how your business can ensure that it is compliant with the rules.

What is a WEL?

A WEL can be defined as the maximum level of concentration of a hazardous substance that can be inhaled by an individual over a specific time period. This measurement is referred to as a time-weighted average. 

The typical workplace exposure limit is eight hours, however, there can be a short term exposure limit of 15 minutes which can be assigned in certain circumstances.

Unlike COSHH regulations which apply to substances that can cause harm through skin contact, ingestion, inhalation and injection, WELs specifically applies to substances that can cause danger to health through inhalation. 

Defining WEL Limits

There are two main measurements that are used to define the limits of WELs. These are:

1. A level where there are no expected dangers to human health based on the substance’s known or predicted impacts.

2. A level that is considered to correspond with sound control, whereby the severity of the possible health hazard, as well as the cost and effectiveness of the control measures, are accounted for.

How to Calculate WEL Limits

How long is the short term workplace exposure limit?

The short term work exposure limit is usually 15 minutes. This is considered to be a sufficient amount of time to control any effects that may be caused after the exposure takes place. This short term exposure limit relates to peak exposure and aims to protect against immediate acute health conditions that could occur as a result of this exposure.  

How long is the long term workplace exposure limit?

The long term work exposure limit is 8 hours. This is the time-weighted average concentration of a hazardous substance that is considered not to cause any injury to health. Businesses have 8 hours to control the effects of the hazardous substance by limiting the overall intake across one or more work shifts. 

LTELs are put in place to protect staff members from concentrations of hazardous substances that could cause long term chronic health conditions over a larger period of time.

In some cases, businesses may be unable to prevent exposure. If this occurs, adequate controls must be implemented in order to safeguard the health and wellbeing of staff. However, measures can only be considered to be adequate if:  

> Workplace exposure limits have not been exceeded.  

> Carcinogens and sensitisers exposure is reduced to as low as reasonably practicable (ALARP)  

> Principles of good practice have been followed and applied

Examples of  WELs

To help you get a better understanding of the types of substances regulated under COSHH laws and those which require workplace exposure limits, below we highlight a number of hazardous substances and their WELs:

> Silica Dust (Respirable Crystalline): 0.1mg/m3 8hr TWA  

> Hardwood Dust: 3mg/m3 8hr TWA  

> Welding fume which consists of the below substances:

– Manganese (Inhalable): 0.2 mg/m3 8hr TWA

– Iron Oxide: 5 mg/m3 8hr TWA 

– Chromium: 0.5 mg/m3 8hr TWA  

If you’re an employer and you have any form of hazardous substance within your workplace, it is paramount that you implement effective control measures in order to safeguard the health and wellbeing of your employees. 

How to Monitor and Stay Within WEL Limits

In order for companies to successfully abide by the regulations of WEL COSHH restrictions and HSE workplace exposure limits, they must ensure that none of their staff, clients, contractors or members of the public are exposed in excess to a hazardous substance in accordance with the Occupational Exposure Limits for that specific material. 

Businesses can quantify the levels of exposure within the workplace through effective workplace exposure monitoring. Regulation 10 of the COSHH legislation states that companies have a responsibility to monitor employees’ exposure to hazardous substances.

To assess the effects of hazardous substances through inhalation, measures such as air sampling are recommended. This procedure will measure the degree of hazardous substances within staff breathing zones as well as the air in surrounding areas of the workplace.

An analysis of the potential health risks of current and new workplace practices should also take place at frequent intervals in order to ensure that employees are protected at all times. Control strategies and safety measures such as fume extraction, dust extraction and LEV (Local Exhaust Ventilation) testing are highly recommended to help keep the workplace safe and in line with WELs and COSHH regulations.

Business owners are advised to pay keen attention to workplace exposure limits regulations, as certain levels of exposure can cause severe health risks which may even take years to appear. Abiding by the regulations of WELs can not only protect employees’ wellbeing, but it could also help to reduce the likelihood of lawsuits against the company for failure to limit the concentration of hazardous substances in the workplace.

To find information regarding workplace exposure limits, you can take a look at a substance or product’s Materials Safety Data Sheets (MSDS).

How Extraction Solutions can help with WELs

At Extraction Solutions, we specialise in the design, supply, installation and maintenance of dust and fume extraction systems. We help businesses across the country keep in line with the regulations of WELs by implementing effective control measures to remove hazardous substances and keep all workers safe within the working environment.

Our team can provide you with a bespoke fume extraction solution that best suits your workforce’s needs. To discuss your needs with one of our experts, give us a call today on 01909 512 148.