Effect of wearing masks on odor detection and recognition

Background: The effect of wearing masks on olfaction remains unclear. Objectives: This study aimed to clarify the differences between the effects of no masks, surgical masks, and N95 respirator masks by conducting both identification and threshold olfaction tests. Methods: Young, healthy volunteers aged >= 18 years and < 30 years without awareness of apparent olfactory disorder were included. All participants filled out a questionnaire on olfaction and completed an acuity smell identification test (Open Essence test) and an olfactory threshold test (T&T olfactometry) while wearing no masks, surgical masks, or N95 respirator masks. Results: In the Open Essence tests, the no-mask group score was significantly higher than those of the surgical- and N95-mask groups. Using T&T olfactometry, the median-detection threshold of the no-mask group was significantly lower than that of the surgical-mask group, and the surgical-mask group threshold was significantly lower than that of the N95-mask group. Similar patterns were observed for the median-recognition threshold. Conclusions: Wearing masks, especially an N95 mask, reduces the ability to detect and identify odors. This disadvantage should be considered by professionals such as healthcare workers, who require proper olfaction to perform appropriate tasks.