Odors count globally: an exploratory study on the number of conscious odor perceptions across 19 locations on five continents

Abstract

People around the world perceive odors in similar ways; however, it remains unclear whether they are equally aware of those present in the ambient air. Previous research on odor awareness has predominantly relied on self-report measures that may be prone to recall bias. To address this, we conducted a large-scale, global study to develop a comprehensive, multilevel model that would explain the variability in the frequency of conscious odor perception across geographic regions, measured through both self-declaration and behaviorally. Our model incorporates both individual and location-related factors to predict odor counts. The study involved specialized chemosensory laboratories in 19 locations across 18 countries and a full sample of 971 participants. Primary analyses were conducted on the full sample, with additional sensitivity analyses performed on a restricted subsample of 549 participants. For the first time at a global scale, we employed a behavioral measure of odor awareness based on odor counting performed 24 h after the testing session. Our results revealed that location accounted for 13.1% of the variability in odor counts, while individual participant characteristics explained an additional 4.4%. Self-assessed odor awareness significantly predicted the number of consciously perceived odors; however, age, gender, and chemosensory sensitivity were not associated with odor counts. This study provides the first global-scale exploration of variability in behavioral odor awareness.