Workplace Exposure Limits

Workplace Exposure Limits

Hazardous substances include dust, fumes, chemicals, vapours, mists, nanotechnology, gases, biological agents and germs that cause disease.

Where substances are classified as carcinogens, mutagens or asthmagens, in order to comply with the Control of Substances Hazardous to Health Regulations 2002 exposure must be controlled to as low as reasonably possible.

Workplace exposure limits are occupational exposure limits approved by the HSE.  Thousands of substances are used at work but approximately 500 substances have WELs.  

There are two time frames when calculating WELs;

Time Weighted Average (TWA) - represents the average exposure over an extended period of time(usually 8 hours)

Short Term Exposure Limit (STEL) - represents the maximum permissible exposure over a short period (usually 15 minutes)

Examples of substances with WELs in place are;

Lead - toxic metal used in various industrial processes
Carbon Monoxide - a poisonous gas produced by incomplete combustion.
Welding Fumes - these can contain various substances such as iron oxide, manganese and chromium

There are also many substances with exposure limits due to the chemicals they contain. Check the Safety Data Sheet to be sure the substances used do not have exposure levels in place.