discomfort threshold

in atmospheric chemistry
https://doi.org/10.1351/goldbook.D01777
The lowest value (e.g. concentration of an impurity, etc.) at which a sensation of discomfort is perceived; a measure which varies from person to person.
Source:
PAC, 1990, 62, 2167. (Glossary of atmospheric chemistry terms (Recommendations 1990)) on page 2185 [Terms] [Paper]