Olfactometrie

Olfactometry is the scientific method used to quantify odor intensity by means of human sensory assessment under controlled conditions. It is commonly employed to evaluate odors from industrial, agricultural, or environmental sources and to compare emission strengths between sites or treatment stages.

The standard approach is dynamic olfactometry, which uses an olfactometer to dilute a sample of odorous air with odorless reference air at defined ratios. A trained panel of sniffers is exposed to the dilutions in a controlled environment, and they indicate whether odor is detectable. The odor concentration of the sample is derived from the dilution level at which the odor becomes detectable by a specified proportion of the panel, typically 50%.

Results are reported in odor concentration units, most often as odor units per cubic meter (ou_E/m3). The method relies on a reference odorant, commonly n-butanol, for calibration and consistency across laboratories. The European standard EN 13725 and related procedures govern equipment, panel selection, calibration, environmental conditions, and data analysis.

Applications of olfactometry include regulatory compliance, odor impact assessment, and permit-related monitoring for wastewater treatment plants, landfills, farming operations, and odor-intensive industries. While instrumental and field-based methods exist, dynamic olfactometry remains the reference technique for determining odour concentration because it directly captures human odor perception, which is central to regulatory and community impact considerations.