Odors in the environment

Olfactory sensation is the culmination of a series of chemical, physiological, memory and cognitive processes, all involved to varying degrees in the stimulation of the olfactory system, the coding of the olfactory message, its transmission, interpretation and restitution. Odor-related issues must therefore be tackled using a multidisciplinary approach, incorporating physical chemistry and neurophysiology, as well as sociology and statistics. In the environment, the study of odors emitted by an installation (e.g., an industrial facility) requires additional knowledge in fields as varied as atmospheric dispersion to describe odor transport phenomena, or industrial processes to characterize the odor molecule formation process or to recommend the most appropriate treatment system.

Legally, olfactory emissions are considered to be a form of air pollution, and manufacturers are now required to integrate this dimension into the management of their facilities, so as not to generate nuisances in the vicinity.

To meet this need, decision-makers need objective diagnostic information to help them choose the most appropriate treatment solutions. An environmental odor metrology system has therefore been developed. It is based on :

• measurements at source, to characterize the emitting environment. These are typically olfactometric measurements, sometimes accompanied by specific physico-chemical measurements;

• measurements in the receiving environment, with impact studies or crisis analyses. They enable us to quantify objectively the odors and nuisances experienced by neighboring populations.

The various themes addressed in this general presentation of the odor problem in the environment will then be detailed in a series of specific articles, written by specialists in the various disciplines concerned.