Comparison of odor detection thresholds for n-butanol and benzaldehyde determined with a dynamic dilution olfactometer and in room air

Abstract

The German Committee on Indoor Air Guide Values (AIR) has developed a concept of odor guide values (OGV) based on odor detection thresholds (ODT) to assess the plausibility of complaints about odor annoyance. ODT were determined directly at the nose with a dynamic dilution olfactometer. However, OGV will be used when a person is exposed to the odor in a room. This study aimed to assess the comparability of ODT determined with a dynamic dilution olfactometer according to the European Standard for Olfactometry EN 13725:2022 with ODT determined in room air under standardized conditions as described in the International Standard ISO 16000–30. ODT for n-butanol and benzaldehyde were determined by each method in 20 healthy, non-smoking volunteers (10 women/10 men, 19–50 years). Participants were screened for normal olfactory function and selected and trained in odor assessment compliant with EN 13725:2022. Comparability of log-transformed ODT values was assessed using Bland-Altman plot analysis. ODT values determined in room air were lower than by dynamic olfactometry. The bias for n-butanol was – 0.48 lg(ppb) (limits of agreement (LoA): – 1.13, + 0.18) and for benzaldehyde – 0.25 lg(ppb) (LoA: – 0.76, + 0.26). Measured differences were considered practically negligible for benzaldehyde, but not for n-butanol. Surface adsorption effects in the dilution system of the olfactometer and differences in the test procedures are discussed as possible causes for this discrepancy. Concluding, ODT determined with an olfactometer directly at the nose are suitable for deriving OGV and can be applied when a person is exposed to odors in room air.