The average ambient temperature in the world has continuously risen since the Industrial Revolution. In the 21st century, we are exposed to high ambient temperature and COVID-19. We are trying to find answers of how to live in the 21st century by studying thermal physiology.
We have been elucidated heat acclimation by cellular and molecular biological methods. We found that water channels, gas mediators, heat shock proteins (HSPs), thermo-sensor, and immunoglobulins are regulated by heat. Interestingly, these molecules are involved in the resistance and permissiveness to various external factors such as heat.
In this study, a relationship between seasonal influenza outbreaks and weather or climate was analyzed for three regions in Okayama Prefecture. The start and peak of influenza outbreaks were independent of severe or warm regional climates. While magnitudes of monthly mean temperature (mean bias) were not so clear for the levels of influenza outbreak, weekly levels related to some extent to weekly mean temperatures. Region- and year-related differences of weekly mean vapor pressure were smaller than temperature. For example, approximately 6 hPa of the weekly mean vapor pressure was good indicator for the level 2 of outbreak regardless of regional and annual climates; this value of vapor pressure corresponded to conditions of 60~70% for hourly virus survival rate and 70~80% for virus transmission rate which have been indicated in the previous research.
This study examined whether the modification of an asphalt-paved road can mitigate pedestrians' heat stress in summer. The five test sections, i.e., the dense-graded, permeable, heat reflective, water-retaining asphalts and the lawn as a comparison material, were constructed with each having an area of 5 m × 5 m at a test field in Toyota city, Japan. The quantities observed at each test section were the vertical temperature distribution including air, surface and underground temperatures, downward/upward longwave radiation fluxes, downward/upward shortwave radiation fluxes, and evaporation rate, besides the air temperature and humidity, wind velocity and direction, precipitation, and global solar radiation at the representative point, and water content of the two small specimens of permeable and water-retaining pavers.
The surface temperature was the lowest on the lawn with the albedo of approx. 0.2, and the second lowest on the heat reflective pavement with the highest albedo of approx. 0.3. The water-retaining pavement had the slightly higher surface temperature than the heat reflective pavement and the albedo close to the lawn. This means the evaporative cooling reduced the surface temperature of the lawn and the water-retaining pavement. In contrast to the heat reflective pavement, the dense-graded and permeable pavements had the obviously higher surface temperatures with the lower albedos of less than 0.1, and the lower reflective solar radiation. Eventually, according to the calculation of the thermal index OET (Occupied effective temperature) which was newly derived, the effect of all-wave radiation on pedestrians was the highest on the heat reflective pavement, the second lowest on the water-retaining pavement, and the lowest on the lawn. The water-retaining pavement could be effective for reducing the human heat stress since the pavement made the evaporative cooling effect last longer than the lawn even if the sunny weather continued.
A wet-bulb globe temperature (WBGT) of greater than 28°C reportedly increases the incidence of heat stroke; however, it is difficult to apply WBGT in common household settings owing to the complexity of calculation. Thus, when making assessments, it is preferable to employ usual room temperature, which is simpler and easier to apply. The ideal usual indoor temperature for preventing heat stroke remains to be clarified─despite the recommended room temperature of 28°C set by Japan’s Ministry of the Environment; that temperature was actually decided to help mitigate global warming. The present investigation was a single-hospital-based prospective observational study to determine the ideal room temperature to prevent heat stroke indoors. It did so by clarifying the proportion of hours of the day with WBGT ≥ 28°C in the rooms of patients aged ≥65 years receiving home-visit nursing care who were prone to heat stroke. In all, 59 patients were enrolled (three patients dropped out). To calculate WBGT, electrical sensors under control of the Internet of Things were installed to monitor the indoor temperature and humidity of each participant’s bedroom every 5 minutes for 14 days. The proportion of hours of the day with WBGT ≥28°C was 0% with a room temperature under 26°C, 18.4% with that of 26°C-27°C, 38.9% with that 27°C-28°C and over 68.0% with that over 28°C. This finding suggests that the recommended room temperature to prevent heat stroke in older patients is under 26°C.