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Understand requirements for occupational exposure limits (OELs)
OELs are regulatory values which indicate levels of airborne exposure that are considered safe for a chemical substance in a workplace.
For airborne exposures, there are three types of limits in common use:
- The time-weighted average (TWA) exposure limit - the maximum average concentration of a chemical in air for a normal 8-hour working day and 40-hour week.
- The short-term exposure limit (STEL) - the maximum average concentration to which workers can be exposed for a short period (usually 15 minutes).
- The ceiling value - the concentration that should not be exceeded at any time.
In addition, biological exposure indices (BEIs) represent the concentration of chemicals in the body that would correspond to inhalation exposure at a specific concentration in air.
Relevant tools
Below is a list of tools relevant for implementing this topic :
- ILO: A 5 step guide for employers, workers and their representatives on conducting workplace risk assessments (2014)
- ILO: Exposure to hazardous chemicals at work and resulting health impacts - A global review (2021)
- ILO: Code of practice - Safety in the use of chemicals at work (1993)
- ILO/WHO: Outline for the development of national programmes for elimination of asbestos-related diseases (2007/2014)
- OECD: eChemPortal