A general obligation to measure hazardous chemical agents and CMRs
Determine which products to measure in workplace air, and how often

Depending on the chemical agent, occupational exposure limit values may be set in the form of VLEP-8H or VLCT :

• Occupational exposure limit values-8h (OELV-8h) are designed to protect the medium- and long-term health of workers exposed to a chemical agent over a working lifetime (chronic poisoning). They represent the time-weighted average concentration of a chemical agent in the air of a worker's respiratory zone over the course of an 8-hour working day.

• Short-term exposure limit values (STELVs or STELVs) are designed to protect workers against the toxic effects of a chemical agent due to exposure peaks (irritation phenomena, for example). It is a limit value corresponding to exposure measured over a reference period of 15 minutes during the exposure peak, whatever its duration.

The various existing values are listed in this document...