Threshold Limit Value

Last updated: May 5, 2017

What Does Threshold Limit Value Mean?

Threshold Limit Value (TLV) is a registered and reserved term of the American Conference of Governmental Industrial Hygienists (ACGIH). It is an occupational exposure value recommended by ACGIH to which it is believed nearly all workers can be exposed for lifetime without affecting health. It is the maximum average concentration of a hazardous material floating in the workplace to which workers can be exposed during an eight-hour work day and 40-hour workweek, over a working lifetime, without experiencing significant adverse health concerns.

Safeopedia Explains Threshold Limit Value

Three types of TLVs for chemical substances are defined: Threshold Limit Value – Time Weighted

  • Average (TLV-TWA) is the average exposure on the basis of a 8h/day, 40h/week work schedule.
  • Threshold Limit Value – Short-Term Exposure Limit (TLV-STEL) is the spot exposure for duration of 15 minutes that cannot be repeated more than 4 times per day.
  • Threshold Limit Value – Ceiling Limit (TLV-C) is the absolute exposure limit that should not be exceeded at any time

TLV is a guideline and not a legal standard. It is determined on the basis of the available data and is revised annually. Only the specialists can interpret these values

There are other types of “Acceptable Exposure” Limits, such as:

  • Occupational Exposure Limits
  • Provisional Exposure Limits
  • Voluntary (Recommended) Exposure Limits
  • Regulatory Occupational Exposure Limits etc.

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