The effects of indoor intermittent sweet orange smell on human relaxation

Abstract

To reduce work stress in humans, this study investigates creating an indoor smellscape environment using an intermittent sweet orange odor-based approach. We used a cross-disciplinary analysis to characterize subjective feelings, physiological indicators, and cognitive levels. The results indicated that the intermittent sweet orange smellscape environment significantly improved the subjects' overall mood state and alleviated their total mood disorder (TMD) by 0.53, as well as boosting their preference for this particular environmental odor. Although ratings of symptoms did not differ significantly between control and smellscape conditions, the smellscape environment alleviated nasal discomfort. The intermittent sweet orange smellscape architectural environment increased Heart Rate Variability (HRV) and reduced Heart Rate (HR), suggesting that it reduced sympathetic nervous system activity and thus promoted relaxation. The results of this study indicate that while both continuous and intermittent exposure to the sweet orange smellscape promote relaxation in humans, intermittent exposure mitigates the deleterious effects of TVOCs. Moreover, intermittent odor release appears to also maintain perceived olfactory intensity and relieve olfactory fatigue caused by continuous smellscape environments. This study shows that the intermittent sweet orange smellscape environment is suitable for leisure and relaxation purposes, which provides a methodological foundation for a healthy building and presents a new perspective on using beneficial odors in indoor environments.