The well known methods that are used to measure the airborne pollutants cannot be used to evaluate odorants in the outdoor air. The German VDI-Guideline 3940 (Determination of Odorants in Ambient Air by Field Inspections) describe a method of measuring odorants in ambient air. The effect on human smell is directly measured with this method. A parameter measured is the “percentage odor time” and represent the frequency at which observers can recognize an odor in the outdoor air. Investigations that were done at dairy and cattle housing showed that representative results can be obtain with 10 plume measurements done during a year period to evaluate the distance at which the odor from a given livestock building can be recognized and “odor boundaries” can be defined. The odor boundaries measured are in general the same for the winter than for the summer. Different parameters have an influence on the intensity of substantial odor and they are: the topographic position of the livestock housing, the housing system, the fodder conservation and storage system and the manure system including the storage.

This publication is an practical example of application of the VDI 3940 for the determination of odor plume boundaries. The method and procedures used to evaluated the odor plume from a dairy and cattle housing are well presented and explained. This odor plume determination technique could be used for any livestock housing.
See: VDI 3940 31 p. Kommission Reinhaltung der Luft im VDI und DIN.