scope:

Purpose and Scope of Validity

This part, which is Part 1, of Guideline VDI 3882 describes an olfactometric method of investigation which can be used to assess inhaled samples having odorant concentrations above the odour threshold (suprathreshold concentrations) in relation to the sensation intensity they induce in human beings. For a given odorant concentration, this sensation intensi¬ ty is substantially dependent on the substance and/or mixture. This means that, as a result of assessing several suprathreshold concentration levels of a particular sample of odorant, hght can be thrown on the Variation in intensity as a characteristic of that sample. The investigation of the odour intensity of individual concentration levels using an olfactometer makes it possible to assess it under field conditions.

In the field of emission reduction, the determination of the intensity of an untreated waste provides guide values for the reduction in odorant concentration needed to keep below a certain odour intensity at the source. In this connection, the assessment will be all the more reliable, the less the untreated gas composition is altered by the reduction technique used (i.e. the reduction in concentration should be the same for all the substances in a waste gas), see Section 6.

The relationship between the odour intensity and the odorant concentration makes it possible to use inten¬ sity determinations carried out on clean gas samples and dispersion calculations for odorants [6] to make forecasts of the theoretically remaining odour intensi¬ ty in the field (ambient air). Perceptible interfering actions due to coergistic effects with other odorant immissions are not allowed for in this connection since they cannot be included in the calculations.

However, the determination of the Variation in inten¬ sity is not on its own sufficient to describe the nuisance potential of an odorant sample (cf Section 6).

The Standards set by this Guideline apply to odour intensity determinations carried out on the following samples :

a) emission samples obtained from a source of odour,

b) individual substances or specified mixtures of substances in neutral air,

c) Immission samples provided their odorant con¬ centration is high enough for an olfactometer to be used (see "Instrumental Minimum Concentra¬ tion" [1]).

If the odour intensity is not measured with an olfact¬ ometer but

- is assessed by field inspections to determine immissions, or

- is to be polled by questioning residents of a polluted area as part of odour nuisance measurements,