The concentration that must not be exceeded is known as what?

• A. TLV-TWA
• B. STEL
• C. TLV-C
• D. PEL

Answer: (C)

The term for the concentration that must not be exceeded is the Permissible Exposure Limit (PEL). PEL is a regulatory standard set by agencies like OSHA and delineates the maximum amount of a hazardous substance that a worker can be exposed to during a specific time frame, typically an 8-hour workday or 40-hour workweek. PELs are crucial for ensuring workplace safety, as they are based on extensive research regarding the potential health effects of various harmful substances.

Other terms listed, while related to exposure limits, have different meanings and applications. TLV-TWA refers to the Threshold Limit Value-Time Weighted Average, which averages exposure over a work shift but does not specifically indicate an absolute limit. STEL, or Short-Term Exposure Limit, sets a maximum exposure limit over a short period (usually 15 minutes) but does not cover long-term exposure. TLV-C stands for Threshold Limit Value-Ceiling, indicating concentrations that should not be exceeded at any time but does not provide a comprehensive guideline like PEL does in terms of general allowable exposure over a longer period.