Definition of workplace exposure limits

Updated February 21, 2017

Workplace exposure limits regulate the acceptable concentration of a hazardous substance in the workplace. These limits are set and enforced by competent national authorities. Each country defines its own limits, resulting in a lack of widely accepted worldwide standards. The goal is to maintain a safe environment for employees to work in while still being as productive as possible without risking their health.


Workplace exposure limits were designed with the intention of limiting workers to excessive exposure of toxic chemicals while on the job. Employers must ensure limits are not exceeded. Typically, limits incorporate safety margins to ensure overexposure does not occur. Hazardous substances include chemicals or products containing chemicals, dusts, vapours, gases and biological agents.


Exposure to a hazardous substance can happen to the human body through the following routes: breathing fumes, dust, gas or mist; skin contact; injection into the skin; or swallowing. Employers must provide safety training and/or equipment to protect employees from exposure.


There are several limit standards put in place to help guide employers and employees as to how dangerous certain hazards are, and how much exposure (if any) is safe. The most common limit standard classifications are Immediately Dangerous to Life and Health (IDLHs), Threshold Limit Values (TLVs) and Recommended Exposure Limits (RELs) developed by the National Institute for Occupational Safety and Health (NIOSH), and Permissible Exposure Limits (PELs) developed by the Occupational Safety and Health Administration (OSHA).


Workplace exposure limits give employees and employers an idea of what level of a particular chemical or toxin is safe, and when exposure becomes hazardous. However, there are some variables that might affect the limit level. For example, if you are a healthy adult, the limits established are reliable. However, if you are an older adult, a young person or in poor health, the limits established might still be dangerous for you, and you should use caution when working with or near hazardous materials, even though the exposure falls within the guidelines established by OSHA.

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About the Author

Chris Newton has worked as a professional writer since 2001. He spent two years writing software specifications then spent three years as a technical writer for Microsoft before turning to copywriting for software and e-commerce companies. He holds a Bachelor of Arts in English and creative writing from the University of Colorado.