In this report, the following findings were obtained as a result of evaluating the relationship between the incidence of heat disorders among the elderly and climatic factors in Tokyo from 2010 to 2015. Elderly people are vulnerable to heat, and heat disorders tends to become more severe. In addition, there are many onsets during daily life, and there is a high possibility that the climatic environment of the residential area will affect it. In 2010, 2011 and 2015, the incidence rate of heat disorders among the elderly was relatively high in Tokyo’s wards and low in Tama municipalities, and the correlation with the accumulation of daily maximum WBGT was higher than that of the daily maximum temperature. In the coastal areas of Tokyo, the daily maximum temperature is lower than that of inland areas, but sometimes the daily maximum WBGT is close and the incidence rate of heat disorders among the elderly is similar to that of inland areas. As a climatic factor for the incidence of heat disorders among the elderly in Tokyo, it was suggested that a phenomenon called a muggy island, in which WBGT is high in the city center, is involved.

In order to prevent heat stroke during bathing, it is effective to use a thermal model of the human body that can appropriately predict the increase in core temperature during bathing under various temperature conditions. In this study, we developed an improved version of the existing Two-node model by dividing the core layer into two parts, and showed the validity of the improved model by comparing the results of the calculation by the model with those of a 10-minute bathing experiment for six male and six female subjects under six conditions: two levels of water temperature (40°C and 42°C) and three seasons (summer 30°C, fall 24°C, and winter 18°C). The error between the measured rectal temperature and the calculated core temperature was 0.15°C in the conventional Two-node model, but improved to 0.11°C in the proposed version of the model. When limited to the 40°C water temperature condition in winter, the error was greatly improved from 0.21°C to 0.10°C. These results indicate that the proposed version of the model, which divides the core layer of Two-node model into two parts, can appropriately predict the rise in core temperature during bathing.

To evaluate the long-term relationship between climate change and plant phenology in spring, record mining of cherry flowering phenology before the Japan Meteorological Agency began recording phenological observations is an important task. We retrieved records of flowering phenology during the Meiji and Taisho eras from the diary of Atomi Kakei, a Japanese educator (1840−1926) and then evaluated the data quality and systematic errors. We were able to retrieve 22 years of flowering dates and 33 years of full-bloom dates across the period from 1873 to 1924. The flowering and full-bloom dates retrieved from this period were about 10 days later than those at present. The records of cherry flowering phenology in the diary may be considered to contain systematic errors of at least a few days caused by the differences of observation points and persons, discrete observation days, and differences of cherry species and individual trees but our findings indicated that diary records of the phenology of cherry flowering is useful for determining the phenological effects of climate change.

We statistically investigated relationships between the mortality of cardiovascular diseases and meteorological conditions in Tokyo 23 wards, Nagoya City, and Osaka City during 15 years in 2005~2019. The generalized additive model evaluated a mortality risk for meteorological parameter changes. The results provided that the mortality of many diseases indicated nonlinear effects for a daily minimum temperature with positive extreme values in both strong cold and hot conditions. However, the air pressure linearly related to mortality of many diseases. Whereas arrhythmia and heart failure mortalities were insignificantly sensitive to daily maximum temperature under both cold and hot conditions, hemorrhagic cerebral diseases and cerebral infarction were sensitive to daily maximum temperature under cold conditions; these showed a different mortality curve to temperature from a U- or V-shapes. Moreover, a mortality risk of arrhythmia and heart failure increased with higher pressure, and that of hemorrhagic cerebral diseases increased with lower pressure. Since mortality sensitivities to meteorological factors differ depending on the type of disease, it is necessary to analyze the disease separately.

The number of indoor heatstroke cases aged 60 years or older categorized the "Residential" in the ambulance transport data was aggregated by perception time to investigate the characteristics of temporal changes in the number of indoor heatstroke cases based on the operation status of air conditioner. Simultaneously, association between the severity of indoor heatstroke, categorized as "mild" and "moderate or severe" and use of air conditioner was investigated using the ambulance transport data (June to October 2013 - 2019) provided by the Toyohashi Fire Department, Aichi Prefecture, Japan. The obtained results showed that 1) the number of ambulance transports due to indoor heatstroke, in which the air conditioner was recorded as "OFF" in the transport data, was found to increase sharply from 7:00 a.m., peaking at 9:00 a.m. and 1:00 p.m. Moreover, more patients were diagnosed with "moderate or severe" in the morning than in the afternoon. The high number of cases of indoor heatstroke in the morning was attributed to the possibility of heatstroke occurring during the night or while sleeping, as well as to the delay in calling for emergency medical services. 2) There was a significant association between air conditioner operation status and severity of indoor heatstroke. The use of air conditioner may reduce the probability of moderate or severe heatstroke by an average of 26 points compared to when the air conditioner was OFF.