Due to the impacts of global climate change, summers in Japan are gradually becoming hotter, resulting in the number of heat stroke fatalities in Japan exceeding 1,000 every year. Considering these circumstances, the 211th Ordinary Diet session enacted “the Act to Partially Amend the Climate Change Adaptation Act and the Act on the Environmental Restoration and Conservation Agency, Independent Administrative Agency” (Act No. 23 of 2023, hereinafter referred to as the “the Revised Climate Change Adaptation Act”). This law became fully enforced beginning in April 2024. These amendments were intended to further enhance measures against heat illness in anticipation of possible extremely high temperatures in future summers. The Revised Climate Change Adaptation Law (1) requires the government to establish an action plan incorporating heat illness countermeasures, (2) places Heat Stroke Alert in the law and creates a new Special Heat Stroke Alert, (3) introduces a system allowing municipal mayors to designate “Cooling Shelters” (heat evacuation facilities), (4) creates a system to empower designated organizations to promote heat illness countermeasures, and (5) adds additional duties related to heat illness countermeasures to The Environmental Restoration and Conservation Agency.

Due to the effects of global warming, Saitama Prefecture faces challenges related to extreme summer heat and heatstroke, with a record high of 41.1°C recorded in 2018—the highest in Japan. In recent years, the number of extremely hot days has continued to increase, and the prefecture ranks among the highest nationwide for emergency heatstroke cases. In response, the Saitama Climate Change Adaptation Center (the Prefectural Adaptation Center) has promoted research and awareness campaigns on heatstroke as part of its broader climate change adaptation efforts. The Center fulfills two main roles: collecting, organizing, and analyzing climate-related data, and providing information to local governments and residents. As a unique initiative, Saitama has also jointly established regional climate adaptation centers with municipalities, with 17 cities and towns participating as of April 2025. On the Kanto Plain, sea breeze patterns contribute to heat environment complexity. Particularly in the central region, which lies downwind of central Tokyo, high temperatures often persist in the afternoon. To monitor these regional variations, the Center developed IoT-based heat index sensors that enable real-time monitoring across multiple locations. Data analysis revealed that the northern part of the prefecture tends to experience longer durations with heat indices above 28°C compared to the south. Local governments are also taking action. For example, Kumagaya City uses digital signage for public outreach, and Fukaya City is collaborating with agri-tech companies. The Center also works with the prefectural health department to intensify public communication during heat alerts. Despite an increase in extremely hot days in 2024, the number of heatstroke-related emergency transports declined compared to that of the previous year, highlighting the impact of these initiatives. The Center will continue to work with relevant agencies to strengthen heat-adaptation measures.

Since 2006, the Heatstroke Committee of the Japanese Association for Acute Medicine has conducted nationwide surveys on severe heatstroke, contributing to our understanding of actual conditions and ability to promote effective countermeasures. In 2015, the committee published the “2015 Heatstroke Management Guideline (G2015)” based on Clinical Questions (CQ), providing specific guidance for clinical practice with a Grade Ⅰ to Grade III severity classification system primarily focusing on symptoms. After approximately 10 years, due to climate change-associated increasing incidence of heatstroke and the accumulation of new evidence, the committee deemed it necessary to update the guideline, resulting in the development of the “2024 Heatstroke Management Guideline (G2024).” G2024 refers to the Minds Guideline Development Manual 2020 and adopts the GRADE system. For CQs lacking sufficient recommendations, topics were categorized as Future Research Questions (FRQ) or Background Questions (BQ), clarifying what is currently known and unknown in heatstroke management. Primary updates in G2024 include clarification of the concept of active cooling, introduction of a Grade IV severity classification, establishment of the quick Grade IV (qGrade IV) concept, and a focus on detailed diagnostic and treatment algorithms. Temperature management methods were divided into “Active Cooling” and “Passive Cooling.” Active Cooling includes immersion in cold water, evaporative cooling, and extracorporeal membrane oxygenation (ECMO), and Passive Cooling includes cooling infusions and resting in cool environments suitable for milder cases. The new classification subdivides the former Grade III into more detailed categories, and defines Grade IV as the most severe, with a core body temperature of ≥40.0°C and impaired consciousness (Glasgow Coma Scale ≤8). Early comprehensive treatment, including Active Cooling, is strongly recommended for patients with Grade IV heat stroke. Data from the Heatstroke Surveillance System (HsS) indicate that the in-hospital mortality rate for patients with Grade IV heat stroke is 23.5%, with an odds ratio of 4.5 for mortality compared to those with Grade III (95% confidence interval: 3.24–6.30). For situations where core body temperature measurement is challenging, G2024 introduces qGrade IV criteria: a surface temperature of ≥40.0°C or obvious heat sensation combined with severely impaired consciousness (GCS ≤8 or Japan Coma Scale ≥100). These guidelines emphasize the need for rapid transportation to advanced emergency medical facilities in such cases. G2024 provides clear treatment protocols based on severity assessment and strongly recommends immediate treatment, including Active Cooling, for qGrade IV and Grade IV cases. The guidelines establish 10 CQs, 7 FRQs, and 7 BQs, but few topics currently include definitive recommendations. The field currently lacks high-quality research, including randomized controlled trials. Therefore, further studies are urgently required.

[Objectives] This study was performed to elucidate the daily maximum WBGT values for each prefecture that correspond to the number of people transported to hospitals for heatstroke and to evaluate regional, seasonal, and age differences in heatstroke occurrence by defining heatstroke occurrence probability (Px). [Methods] Px was defined as the ratio of the number of days when the number of heatstroke emergency transport patients per million people was x or more to the total number of days in the relevant category, which was divided into categories of 1ºC for the daily maximum WBGT. The daily　maximum WBGT when Px is 50% (Wx) can be considered as the threshold value for the number of emergency heatstroke transport patients per million people. Px was calculated for each month and age group under the following four conditions: x = 1, 2, 5, and 10. Furthermore, we created three types of regression models for Px using binary logistic regression analysis (an all-ages, all-period model; an all-ages, monthly model; and an age-specific, monthly model) and verified the validity of the regression models using indices of negative predictive value, positive predictive value, and area under the curve. Finally, we evaluated regional differences in heatstroke risk using Wx by prefecture. [Results] When Px for Tokyo was calculated by month or age group, and the daily WBGT maxima were analyzed when they were 50% or higher, the highest maxima were found in the following orders: September>June to August>May; and adults>children>the elderly. When a regression model was created, the positive predictive value of the monthly and age-specific models was sometimes 0% owing to data imbalance; however, the Wx obtained from the all-age, all-period model and the all-age, monthly model was considered valid. Finally, when Wx was evaluated by prefecture, Wx was clearly lower in relatively cold regions. [Conclusion] Px and Wx values revealed that regional differences and seasonal variations in daily maximum WBGT should be taken into account during heatstroke emergency transport, and age should also be taken into account if analysis is limited to the elderly. In recent years, some local governments have built systems that automatically issue warnings based on WBGT measurements. The results of this study may be useful for local governments when setting warning criteria.

Wet Bulb Globe Temperature (WBGT) is widely used in fields of labor, sports, school education, and general living environments as an informative parameter for preventing heat disorder. A WBGT measuring device is required to obtain this value. In general, in living environments where heat disorder often occurs, WBGT measuring devices are almost unavailable. In 2008, the Japanese Society of Biometeorology developed and released a “Simplified WBGT estimation chart for indoor environments” as a tool for estimating WBGT based on air temperature and relative humidity. This estimation chart has been widely used, but it underestimates WBGT in environments with sunlight and overestimates this value in indoor environments without sunlight. A risk of misuse has also been found in that the range of applicability of the simplified estimation chart is not clearly stated. A revised estimation chart, which can only be applied to indoor environments without sunlight, has thus been developed based on heat balance theory and released in 2022. This revised estimation chart was able to make very accurate estimations in indoor environments without sunlight as assessed by comparing it with actual WBGT measurements. The revised version of the estimation chart is extremely useful for countermeasures against heat disorder in indoor environments where heat disorder is common.

We analyzed the occurrence of heat stroke in workplace in Hokkaido, using heat stroke cases from the Hokkaido Labor Bureau from 2017 to 2024. During this period, 510 cases of heat stroke occurred in workplaces in Hokkaido, 63% of which occurred outdoors. Since there are two peaks in the number of heatstroke cases outdoors, at 11:00 and between 14:00 and 15:00, taking a short rest around 14:00 is suggested as a countermeasure. When the outside temperature exceeds 26°C, several people may suffer heat stroke in a single day. The most frequently mentioned terms in the text on the occurrence of heat stroke during work were terms related to "mowing" outdoors and "factory" and "plastic greenhouse" indoors. It is necessary to raise awareness of heat stroke prevention among construction and manufacturing workers, and among those working in agriculture and forestry. We also reviewed research on fan-equipped work clothes and summarized findings to date on their efficacy. In an experiment with 12 construction workers in a standardized thermal environment in an artificial climate room, physiological and psychological responses were compared between conditions in which ventilated working-jacket (VWJ) was worn over a long-sleeved T-shirt and those in which only a long-sleeved T-shirt was worn. At 34°C, mean skin temperature and clothing sweat content were significantly lower when VWJ were worn. In an outdoor field test of seven construction workers at a construction site in Tokyo, mean skin temperature was significantly lower for workers wearing VWJ than for those who wore only long-sleeved T-shirts in the same air temperature. The relationship between thermal and comfort sensations was significantly stronger among those wearing VWJ. These studies revealed that drinking water intake among construction workers was much lower than that among athletes during sports and that wearing VWJs at construction sites effectively reduced the dehydration rate. Provision of an appropriate volume of drinking water and mandating VWJ use effectively reduces the risk of heatstroke. These results suggest that wearing VWJs may be effective in WBGTs within 23–28 °C.

By evaluating heatstroke occurrence and examples of accidents under school supervision, this study explores the prevention of heatstroke in schools by implementing tangible and intangible countermeasures and explaining good practices across Japan based on the “Guide to Creating Guidelines for Heatstroke Countermeasures in Schools” Countermeasures against heatstroke in schools have progressed to a certain extent. However, given the highmobility of teachers and students, it is necessary to continue taking measures to keep up with the current levels.

Objective: We reviewed the public health policies of major countries regarding heatstroke and heat-related illnesses, focusing on the content of each country and region's plans, and considering distinctive initiatives and their applicability to Japan. Methods: We examined the content of Heat Health Action Plans (HHAPs) and related plans as well as academic papers published on the Global Heat Health Information Network and websites of national and local governments in 17 G20 member countries. We reviewed each country's policies based on the eight core elements of HHAPs proposed by the World Health Organization Regional Office for Europe. Results: while many countries have implemented measures, including establishing early warning systems, criteria and indicators vary by country. For example, each province in Canada has its own set of weather parameters and thresholds for issuing warnings. In Italy, warnings are sent to individuals through smartphone applications. In Australia, regulations are in place for housing design, and in China, Canada, Australia, and other countries, community building is promoted among older people living alone. Conclusion: We found that some countries have implemented effective early warning systems and measures that consider high-risk environments and populations including homes and older people.

Objectives: Primary care plays a crucial role in preventing the exacerbation of non-communicable diseases and managing them effectively. Ambulatory care sensitive conditions (ACSCs) are defined as conditions where hospitalizations can be avoided through appropriate ambulatory care. Although health insurance reimbursement schemes in primary care include a “fee for a comprehensive review on care for outpatients,” the impact of this financial incentive on healthcare outcomes remains unclear. The present study aimed to determine whether this fee schedule was associated with reduction in hospitalizations due to ACSCs primarily treated in clinics. Methods: This study included patients who were i) aged 65 years or older, ii) diagnosed with and treated for heart failure, hypertension, diabetes, or hyperlipidemia, and iii) reimbursed for “fee for medication for the specific lifestyle-related diseases” for three consecutive months from the first follow-up examination in a clinic. We conducted a one-to-four propensity score matching between patients with and without the “fee for a comprehensive review on care for outpatients.” The primary outcome was hospitalizations related to chronic ACSCs that could be prevented with appropriate ambulatory care. Results: The propensity score matched cohort included 5,188 patients with the fee and 1,297 patients without the fee. No significant difference was observed in hospitalizations related to chronic ACSCs (1.4% vs. 1.7%, p=0.472) between the two groups. Conclusion: The incentive scheme was not associated with hospitalizations related to chronic ACSCs among older outpatients with stable conditions who received treatment for either heart failure, hypertension, diabetes, or hyperlipidemia in clinics.

This study aims to examine the individuals' dietary behavior, dietary knowledge and socio-economic factors that influence the longitudinal change in vegetable intake. Data from health and nutrition surveys in Nishinoshima town, a remote island in Shimane prefecture, at the time of formulating health promotion plan (2014) and the mid-term evaluation (2021) were used. A total of 135 men and women aged 20s to 70s who responded to both surveys were included in the analysis. Paired statistical tests were used to compare the characteristics and vegetable intake of the subjects at the two time points. A multiple regression analysis was used to examine the factors that influenced the changes in vegetable intake between 2014 and 2021. A significant reduction in vegetable intake was observed between 2014 and 2021. A multiple regression analysis showed that changes in ‘family composition (from living together to living alone)’ and ‘frequency of a well-balanced diet (combination of staple food, main, and side disdishes)ʼ were significantly associated with changes in vegetable intake. A longitudinal study using health and nutrition survey data in the town sug-gested that individual dietary behavior and socio-economic factor influence the changes in vegetable intake.

Objective: The aim of this study was to examine the detailed instrumentation, equipment, and use associated with falls among community-dwelling older adults. Additionally, the study aimed to assess the injury rates by instrumentation, equipment, and use according to the characteristics of the injured individuals, and to identify the instrumentation, equipment, and use that cause severe injury. Methods: We analyzed individuals aged 65 years and older who fell on their property and required emergency medical transport to a hospital in 2019. We calculated injury rates and 95% confidence intervals per 100,000 person-years for each age group (classified as 65-74, 75-84, and 85 years and older) and sex for each type of instrumentation, equipment, and use, as well as the number of moderate or severe injuries and their percentages. Instrumentation and equipment associated with falls were categorized using the ICD-10 and subdivided according to conditions of use. Logistic regression analysis was conducted to identify instrumentation, equipment, and use attributable to moderate or severe injuries, adjusting for sex and age group with the floor as a reference. Results: A total of 4,421 patients were included. Patients were categorized according to 44 different types of instrumentation, equipment, and use associated with falls. A total of 2,154 cases (48.7%) were classified as moderate or severe. Older adults had higher fall injury rates on floors (injury rates, 450.9; 95% CI: 434.5-467.9), stairs (76.6; 69.9-83.8), beds (25.5; 21.7-29.8), steps (21.2; 17.7-25.1), and toilets (14.5; 11.6-17.8), with variations based on instrumentation, equipment, and use as well as sex and age group. Logistic regression analysis revealed that the odds ratio for moderate or severe injuries was higher for falls occurring onthe roof (odds ratio, 8.95; 95% CI: 1.52-169.40). Conclusion: Fall injury rates and the characteristics of the injured individuals among community-dwelling older adults differ based on the instrumentation, equipment, and use associated with falls. The implementation of measures to mitigate external factors associated with this risk are necessary.