Odor and Irritation Thresholds for Ammonia: A Comparison between Static and Dynamic Olfactometry

Abstract

Odor and lateralization (irritation) thresholds (LTs) for ammonia vapor were measured using static and dynamic olfactometry. The purpose of the study was to explore the test-retest reliability and comparability of dynamic olfactometry methodology, generally used to determine odor thresholds following European Committee for Standardization guidelines in the context of odor regulations to outside emissions, with static olfactometry. Within a 2-week period, odor and LTs for ammonia were obtained twice for each method for 24 females. No significant differences between methods were found: mean odor detection thresholds (ODTs) were 2.6 parts per million (ppm) for either method (P = 0.96), and mean LTs were 31.7 and 60.9 ppm for the static and dynamic method, respectively (P = 0.07). Test-retest reliability was higher for the dynamic than for the static method (r = 0.61 vs. 0.14 for ODTs and r = 0.86 vs. 0.45 for LTs). The choice of optimal method for any application, however, depends not only on psychometric factors but also on practical factors such as physicochemical properties of the compound, availability of equipment and expertise, task efficiency, and costs.

Two Rapid Odor Threshold Methods Compared to a Modified Method of Constant Stimuli

“…Both test-retest correlations (0.88 for staircase, 0.43 for FC-AML) are well within the ranges reported for comparable tests of other compounds (e.g., Cain and Gent 1991;Doty et al 1995;Lötsch et al 2004;Smeets et al 2007). In addition, we can ask whether validity, defined as correlation with MCS thresholds, approaches the theoretical limits imposed by reliability.…”

Interactions between the chemical senses: Trigeminal function in patients with olfactory loss

“…There are, however, techniques available that allow for assessment of trigeminal chemosensory function in normosmic controls. These include (a) methods that strongly depend on trigeminal stimulation (e.g., lateralization tasks, breathing responses; Kendal-Reed et al, 1998;Hummel et al, 2003), (b) tests where subjects are trained to focus trigeminal sensations (e.g., psychophysical thresholds; Frasnelli and Hummel, 2005;Dalton et al, 2006;Smeets et al, 2007) and (c) techniques where relatively selective trigeminal stimulants are applied (e.g., gaseous carbon dioxide; Fröhlich, 1851;Stevens et al, 1982).…”

A comparison of sniff bottle staircase and olfactometer-based threshold tests

“…Olfactometers have, in general, been limited to laboratory work, but few attempts have been made to incorporate olfactometers in threshold measurement at all (Johnson & Sobel, 2007). The most popular olfactometer threshold test typically implements the method of ascending limits (Smeets et al, 2007), but as a method of psychophysics, it is longer and more complicated to implement than the popular and wellestablished staircase method (Doty, 1991b). As a result, olfactometer threshold measures have rarely been used in large population studies or widespread clinical applications, despite staircase procedures being somewhat laborious (Doty, 1991a;Johnson & Sobel, 2007).…”