This review aimed to investigate the effects of vertical air temperature differences (VTD) for chair-seated persons, based on human subject tests in a laboratory, on thermal comfort, mental performance, and physiological responses. Recent studies have shown that the acceptable VTD range can be expanded from 3 k/m, as stipulated in ASHRAE Standard 55 (2017) and ISO 7730 (2005), up to 8 k/m. However, females with higher air velocities in the lower body parts and uncovered lower legs should have a narrow range. The VTD for the elderly should be less than 3 k/m because the elderly’s ability to perceive lower body thermal comfort decreases more than that of the young, and the blood pressure of the elderly increases significantly with lower body temperature. A smaller VTD is recommended, particularly in the winter. The effect of VTD on thermal comfort revealed that the preferred temperature of the lower body is several degrees (1.3-6.0°C) higher than that of the upper body. This means that the so-called “cool head and warm feet” condition induces thermal comfort. In addition, lower-body clothing provides less insulation than upper-body clothing, especially for females, and the physiological and morphological characteristics of humans, such as upright bipedal locomotion and a highly developed brain, might influence the thermal responses to VTD. It was shown that more comfortable VTD conditions (the so-called “cool head and warm feet” condition) may induce sleepiness and adversely reduce mental performance. These conclusions, however, may not apply to more complex and long-term (more than 3-hour) mental performance. When evaluating VTD physiologically, measurements of skin temperatures, including peripheral body sites, and blood pressure are essential for the elderly.

The objective of this study was to clarify the increase in SET* due to an outdoor campfire. Measurements were carried out at a public campsite located within Kasugai City, Aichi, Japan on the night of September 19, 2020. The campfires were constructed twice, using mainly pine firewood, at a fire pit there, and the thermal parameters around the campfire were measured. The campfires were found to raise the air temperature at a horizontal distance of 1.5 m from the flame and 1.1 m above the ground by a maximum of 3.5–3.9°C and the globe temperature by a maximum of 4.7–6.1°C. At a distance of 1.5 m from the flame, the campfires raised the plane radiation temperatures facing the campfire by 32.5–36.3°C. Since the radiation emitted from the campfire did not irradiate the back of the sensor, the plane radiation temperature on this side did not rise at all. Within a distance of 1.5 to 2.5 m from the flame, the campfire could provide occupants with a comfortable and acceptable thermal environment. At a distance of 1.5 m from the flame, the campfire raised the SET* by 4.8–6.7°C. The greater the distance from the flame, the smaller the rise in SET* due to the campfire. There was no thermal effect from the campfire flame at a distance of 4 m and above.

In this basic study related to the use of fragrances in offices and car cabins, the physiological effects of fragrances (odors) on cognitive performance were analyzed in association with their psychological effects. A visual search task simulating the acquisition of visual information while driving was used, and behavioral, physiological, and subjectively reported indices were analyzed to estimate the effects of odors while performing the task. To analyze physiological effects, an electrocardiogram (ECG) and an electroencephalogram (EEG) were recorded, and heart rate variability and EEG power (theta, alpha, beta) at Fpz were calculated. Analysis of covariance using the data before odor delivery as covariates was used to compare the changes in each index across the odor conditions. Linear mixed-effects models were used to analyze the relationships between the behavioral and physiological indices in association with the results of the subjective reports. The mental strain induced by the task appeared to be attenuated by the effect of odors modulating the autonomic nervous system, and prefrontal cortical activation and mental relaxation were achieved without a deterioration in performance. The results further indicated that the physiological effects of odors might be associated with psychological effects such as improving motivation and increasing general activation. In the context of cognitive task performance, the odor effects were not always sedative; rather, they modulated activity to a level appropriate to perform the task.