scope:

Purpose and Scope of Validity

Part 2 of Guideline VDI 3882 describes an olfacto¬ metric method of evaluating the hedonic tone of odorous samples with above-threshold odorant concentrations according to the sensation scale "pleasant - unpleasant". The hedonic tone of an odour is contingent on the nature or mixture of the odorous substance or substances, on the odorant concentration - and hence on the perceived intensity of the odour - and on the background experience of the individual person. This means that, by evaluating several above-threshold stages of concentration of a specific odorous sample, it is possible to plot the hedonic odour tone as a characteristic curve of the sample under investigation.

The hedonic tone of an odour must not be confused with its quality (fragrant, pungent, stale, or smelhng like . . .).

In conjunction with the methods recommended in GuideUne VDI 3881 Parts 1 to 4 and GuideUne VDI 3882 Part 1 [1 to 5] for determining odorant concentration (odour threshold) and odour intensity, the additional determination of the hedonic odour tone of an emission sample frequently permits an assessment of its nuisance effect under ambient air conditions, though a conclusive assessment of the actual degree of nuisance is not possible with olfacto¬ metric methods alone. In such cases where it is necessary to ascertain the nuisance effect, additional sociological methods (e.g. neighbourhood surveys) can be helpful [6; 7].

This Guideline is vahd for the determination of the hedonic odour tone of the following types of sample :

a) emission samples from a source of smell,

b) Single substances or defined mixtures in a neutral gas,

c) ambient air samples, insofar as their odorant concentration is high enough for detection by the olfactometer (see [1] and [4] "Instrumental mini¬ mum concentration ").