https://doi.org/10.1351/goldbook.16084
- Intensity, where the detection threshold level is defined as the lower limit of the perceived intensity range (by convention, the lowest concentration that can be detected in \(\pu{50\%}\) of the cases in which it is present).
- Quality, where the recognition threshold level is defined as the lowest concentration at which the sensory effect can be recognized correctly in \(\pu{50\%}\) of the cases.
- Acceptability and annoyance, where the nuisance threshold level is defined as the concentration at which not more than a small proportion of the population, less than \(\pu{5\%}\), experiences annoyance for a small part of the time, less than \(\pu{2\%}\).
Note: Since annoyance will be influenced by a number of factors, a nuisance threshold level cannot be set on the basis of concentration alone.