Olfactometric analysis or odor measurement by sensory analysis

The olfactometric analyses presented here apply to odors of industrial origin that may cause a nuisance to local residents.

The aim of olfactometric analyses is to measure various distinguishable quantities, depending on whether they enable odors to be quantified, qualified or associated with a pleasant or unpleasant character (the notion of hedonism). In other words, we need to answer the following questions: "Is there a smell, and if so, how much? What is its nature? Does it appear pleasant or unpleasant to people living near the emitting site?

The analyses carried out take into account the specific nature of the quantities measured, namely that odour and the olfactory discomfort it may cause are the result of the interaction of chemical molecules with an olfactory system: the use of human noses to carry out olfactometric analyses therefore makes it possible to account for the coupling between molecules and the olfactory mucosa, as well as the processing of information in the brain. At the same time, conventional physico-chemical measurements provide information on the composition of odorous air, but never on the "smell" itself.

In addition, olfactometric analyses take into account the great sensitivity of the human olfactory system, which can perceive chemical signals corresponding to molecular concentrations so low that conventional chemical analyzers fail to detect them. They also make it possible to take into account the properties of the olfactory mucosa in relation to mixtures of odorant molecules; indeed, when the mucosa is subjected to a mixture of molecules, there may be inhibition or exacerbation of odor signals that would have been obtained from molecules taken in isolation.

The aim of this document is to present firstly the quantities measured and the methods used for this purpose, and then the common applications for each of the methods.