Due to the construction of airtight housing, which has been developed to conserve energy in order to prevent global warming, and heat island phenomena caused by urbanization, it has become commonplace for families living in modern homes in Japan to own one or more air-conditioners. At offices, a lot of electronic equipment releases heat all day long. It is not uncommon for relative humidity levels to fall below 20% in air-conditioned rooms, which can cause the occupants’ facial skin to become dry. Severe skin drying can occur in people with reduced skin barrier function, e.g., those with atopic dermatitis, middle-aged women, the elderly, etc. Although conventional humidifiers have been used to moderate skin dryness in air-conditioned rooms, some problems have arisen, such as thermal dissatisfaction caused by increases in humidity during summer; dew condensation on windows during winter; the growth of bacteria in water for humidification; and debate regarding the optimal placement of air-conditioning units in terms of effectiveness and safety, etc. In recent years, the generation of nanosized particles and ions using electrospray techniques has been successfully employed to create indoor water vapor via the Peltier effect; i.e., the “mist” described in the present paper. In addition, home appliance and cosmetic companies have started to incorporate mist generators in health/beauty equipment. The nanosized droplets emitted from such equipment are expected to penetrate into the stratum corneum and improve its moisture content. However, little data about the biophysical and physiological effects of such droplets have been reported. A new type of air-conditioner containing a mist generator has recently been tested during summer and winter to examine whether it could contribute to moisturizing and softening skin without increasing ambient humidity. The present paper reviews recent studies regarding the effects of mist on the biophysical and biomechanical properties of skin.

We investigated how differences of topographical and geographical environment influence on the summer heat stress, by using the air temperature and two heat stress indices (MDI and ESI). Our meteorological observations were conducted in seven sites of inland, plain, coast, and island regions. A heat stress evaluation with air temperature exhibited a higher appearance of the heat hazard in order of inland, plain, coast, and island regions. The excess heating of atmosphere was possibly observed in more urbanized region. On the other hand, a heat stress evaluation with MDI showed a different result from the air temperature, which was a higher appearance of the severe warning hazard in order of plain, inland, coast, and island regions. The high stress in plains was thought to be due to an exposure of humid air such as a sea breeze penetration. The additional evaluation by ESI which includes solar radiation effects indicated the further different result from the above index results; an appearance of the severe warning hazard in coastal and island regions, where less clouds cover, increased compared to a use of MDI, and it increased a heatstroke risk in these regions. On the other hand, appearances of the severe warning hazard in inland regions decreased due to the insolation decrease.

The heat during the Tokyo 2020 Summer Olympics will presumably be especially demanding for marathon runners. Therefore, the present study measured WBGT over the same three days in 2015 which correspond with the event in 2020. By using a road bike with mounted environmental thermometers, a run-through of the scheduled course from start to finish at a speed of 20 km/hr was simulated. Simulation conditions which included the speed of the marathon runners along with WBGT exposure that they could expect were examined to assess the related risk of heat stroke. The mean WBGT over the entire course on the road-bike was 30.4°C and thus higher than 30°C on July 26, and 29.6°C on August 4 and 26.9°C on August 9. The mean dry-bulb temperatures were 36.9°C on July 26, 34.5°C on August 4, and 32.4°C on August 9. The mean WBGT values obtained from concurrent stationary measurements at five locations along the course were just 0.2±0.1°C (range 0.1 to 0.3°C) higher than the mean values obtained from the moving road-bike measurements. These WBGT values indicate that athletes are exposed to a higher temperature while running than that commonly expected, which, along with the additional burden of body-temperature elevation occurring during an over 2-hour long marathon, sufficient training and acclimation under summer heat will be necessary to avoid heat stroke and permit a high level of performance. In this study, we set start time for marathon at 8:30, but think the start time to have to shift early in the morning. Furthermore, we install much mist showers in the marathon course route and think that it is necessary to make use for the physical cooling of the marathon runner.

Persons with spinal cord injuries suffer from disorder of thermoregulation including defective sweating and vasomotor disturbance over most of the body. As we expect sustained physical activity to be one of the methods to alleviate burden on the body against heat stress and to reduce dependency on cooling and heating equipment of persons with spinal cord injuries, a 24 or 42-month longitudinal survey was conducted on three persons with spinal cord injuries (each with cervical spinal cord injury, thoracic cord injury and lumbar cord injury) to understand the relationship between sustained physical activity and changes in adaptability to thermal environment. As a result of measuring axillary temperature upon awakening, the level of axillary temperature tended to increase for the person with cervical spinal cord injury, and axillary temperature tended to converge to a narrow temperature range for the person with lumbar cord injury. Furthermore, response to adapt to room temperature began to appear in the skin temperature on the paralyzed segment for persons with cervical spinal cord injury and lumbar cord injury, based on experiments in an artificial climate chamber. This survey indicated that sustained physical activity might improve the adaptability to thermal environment for persons with spinal cord injuries.