Definition

Threshold Limit Values (TLV) are a set of workplace exposure limits recommended by the American Conference of Governmental Industrial Hygienists (ACGIH). TLVs are intended to guide and assist industrial hygienists, occupational health professionals, and employers in managing and controlling workplace exposures to various chemical substances and physical agents. Types of TLVs: ACGIH provides various types of TLVs, including Threshold Limit Value-Time-Weighted Average (TLV-TWA), Threshold Limit Value-Short-Term Exposure Limit (TLV-STEL), and Threshold Limit Value-Ceiling (TLV-C).

TLV-TWA: The TLV-TWA is the time-weighted average concentration of a substance to which most workers may be exposed during a typical workday.
TLV-STEL: The TLV-STEL is the concentration to which workers may be exposed for a short duration (usually 15 minutes) without experiencing adverse effects.
TLV-C: The TLV-C is the maximum allowable concentration that should not be exceeded at any time during a worker’s exposure.