Let’s get into the weeds on the process of quantifying the relative strength of ambient air. Field olfactometry is a reliable method of measurement using a portable olfactometer, informally referred to as a “scentometer.” V&A recently used the Nasal Ranger® Field Olfactometer as part of a wastewater odor control evaluation. The Nasal Ranger “creates a calibrated series of discrete dilutions by mixing the odorous ambient air with odor-free (carbon) filtered air”1. The odor strength is quantified in terms of “Dilution-to-Threshold” (D/T) ratios, a measure of the number of dilutions required until the sample no longer has any detectable odor. Field olfactometers provide a scientific, repeatable method for determining background odor concentrations, investigating odor complaints and documenting the severity of specific events, prioritizing odor sources for detailed analysis, and verifying the assumptions used in odor dispersion modeling.
1 Nasal Ranger® Field Olfactometer Operation Manual, St. Croix Sensory, 2008.