Olfactometric

Olfactometric refers to the measurement of odours using olfactometry, a technique in which human assessors evaluate odour concentration and intensity by exposure to controlled dilutions of a sample. The standard method is dynamic olfactometry, often conducted with an air-dilution olfactometer that blends odorous air with odour-free carrier air.

In dynamic olfactometry, a panel of trained assessors, typically six to eight or more, is exposed to a series of dilutions of the sample. The panel determines the dilution at which odour becomes detectable, and may also rate odour intensity relative to a reference odour. Results are expressed as odour concentration in odor units (OU), representing the dilution factor at threshold, or OU_E in some European standards, with higher values indicating stronger odour emissions.

The method is standardized in EN 13725 (Air quality – Determination of odour concentration by dynamic olfactometry). It emphasizes dose–response assessment, panel training, environmental control, sanitation, and blind testing. Field olfactometry adapts the approach for on-site measurement using portable devices, offering a more rapid, though often less controlled, alternative for certain applications.

Applications of olfactometric measurement include regulatory compliance, environmental monitoring, wastewater treatment, landfills, animal housing, and industrial odor control. Advantages include direct relevance to human perception and broad regulatory acceptance. Limitations involve panel-to-panel variability, substantial cost and time requirements, and sensitivity to environmental factors such as background odors, temperature, and humidity, which can influence results.