ACGIH Threshold Limit Values (TLV)

TLVs are not regulations. The ACGIH is a scientific body, and its values are recommendations, reviewed and updated far more frequently than statutory limits. Because they track current toxicology, TLVs are often stricter than the corresponding legal limit and are widely treated as best practice. The specific values are given in the limit table on this page.

Industrial hygienists, occupational-health professionals, and safety managers use TLVs as the benchmark for protecting workers, particularly where the enforceable limit is dated or absent. Many organizations adopt TLVs voluntarily as an internal exposure ceiling, and regulators, insurers, and courts in various jurisdictions reference them as the recognized state of the science. They apply across the same industries as legal limits (manufacturing, chemicals, construction, mining, laboratories, and beyond), wherever airborne hazards are managed to a health-based rather than merely a legal standard.

Because TLVs share the TWA, STEL, and ceiling framework of enforceable limits, they are assessed with the same measurement approach: personal sampling in the breathing zone over the relevant averaging period, compared against the values in the limit table on this page. Real-time gas monitors capture the concentration profile of vapors and gases through a shift, while dust and mist exposures are measured with size-selective samplers or direct-reading aerosol monitors. As with any occupational panel, no single device covers every substance, so instruments are combined to match the hazards present, and area monitors supplement personal sampling to locate sources.