TLVs and BEIs are health-based values established by committees that review existing published and peer-reviewed literature in various scientific disciplines (e.g., industrial hygiene, toxicology, occupational medicine, and epidemiology).

TLVs ® for aerosols are usually established in terms of mass of the chemical substance in air by volume. These TLVs ® are expressed in mg/m 3. TLVs ® for gases and vapors are established in terms of parts of vapor or gas per million parts of contaminated air by volume (ppm), but may also be expressed in mg/m 3.

This section has been established to help educate industry, government, and the public on what TLVs and BEIs are, and how TLVs and BEIs may best be used.

The Threshold Limit Value for Chemical Substances (TLV®-CS) Committee is appointed by the Board of Directors of ACGIH® to develop occupational exposure guidelines for chemical substances. The issuance of Threshold Limit Values (TLVs®) and their supporting Documentation is …

TLV ® categories used in this section include the following: Threshold Limit Value–Time-Weighted Average (TLV–TWA). The time-weighted average exposure for an 8-hour workday and 40-hour workweek. Threshold Limit Value–Ceiling (TLV–C). Exposure limit that should not be exceeded even instantaneously. Physical and Chemical Factors

ACGIH is a 501(c)(3) charitable scientific organization that advances occupational and environmental health. Examples of this include our annual editions of the TLVs and BEIs book and work practice guides in ACGIH’s Signature Publications. ACGIH’s key mission is – To Protect Workers Around the World. ACGIH is fighting for you!

The TLV-CS Committee consists of three technical subcommittees: • Particulate and Inorganic Compounds (PIC). • Hydrogen, Oxygen, and Carbon Compounds (HOC).

Cincinnati, Ohio — January 7, 2021 — ACGIH announced that its Board of Directors ratified the 2021 Threshold Limit Values (TLVs) for Chemical Substances and Physical Agents and Biological Exposure Indices (BEIs).

Provided below is an overview of the ACGIH ® TLV ® /BEI ® Development Process. Additional information is available on the ACGIH website . Please also refer to the Process Flowchart at the bottom of this page.

ACGIH Data Hub – 2025. Data Hub provides ACGIH Subscribers unlimited access to TLVs, BEIs, and corresponding scientific Documentation. To enroll as an ACGIH subscriber, click here.