threshold limit value–ceiling

initialism: TLV-C
https://doi.org/10.1351/goldbook.16137
As defined by ACGIH, concentration of a potentially toxic substance that should not be exceeded during any part of the working exposure.
Source:
PAC, 2007, 79, 1153. (Glossary of terms used in toxicology, 2nd edition (IUPAC Recommendations 2007)) on page 1321 [Terms] [Paper]