Both characterization of odors via chemical analysis and sensory analysis have advantages and drawbacks. The classical chemical analysis provides information of some
compounds found in an odor. Rarely this chemical analysis covers all compounds of odors found at industrial facilities since it can be composed of hundreds of chemicals. No information on how the odor is perceived by humans is provided by the chemical analysis.
On the other hand, olfactometry does not provide information of the chemical composition of an odor but is focused on how it is perceived by the average human nose. This approach is using the sense of smell of panelists to define the concentration of an odor in odor-unit per cubic meter (o.u./m3).
The white paper "Olfactometry VS Chemical Analysis" presents the differences between the main approaches to quantifying odors: chemical and olfactometry analysis.