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[HGPI Policy Column] (No.76) – From the Planetary Health Project “No. 19: Heat and Health – The Health Risks of Climate Change and Society’s Preparedness”

date : 8/7/2026

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[HGPI Policy Column] (No.76) – From the Planetary Health Project “No. 19: Heat and Health – The Health Risks of Climate Change and Society’s Preparedness”

<POINTS>

  • As climate change advances, the frequency of heatwaves and extreme heat is rising around the world. Heat has become a major public health issue, causing not only heatstroke but also a range of health impacts such as the worsening of cardiovascular and respiratory diseases.
  • Led by the WHO and the WMO, comprehensive heat countermeasures such as Heat-Health Action Plans (HHAPs) are being promoted. Countries are pursuing cross-sectoral efforts that combine early warning systems with the protection of vulnerable populations.
  • In Japan, while the operation of Heatstroke Alerts and the development of legislation have advanced, there is a need to strengthen comprehensive heat countermeasures, support for vulnerable populations, and measures tailored to regional characteristics.
  • Heat is closely linked not only to health but also to climate change, energy use, housing conditions, and health disparities. From a planetary health perspective, it is important to advance sustainable countermeasures through collaboration across multiple sectors.


Introduction

In recent years, Japan has repeatedly experienced record-breaking heat, and the number of people transported by ambulance due to heatstroke has been increasing. Heat is no longer merely a temporary weather anomaly; it has become a public health challenge with major impacts on people’s health and daily lives.

This trend is not unique to Japan. The World Meteorological Organization (WMO) reports that global average temperatures are likely to remain at record-high levels over the coming years, raising the risk of extreme heat events, including heatwaves. As climate change continues to advance at a rapid pace, concern about the health impacts of heat is growing worldwide.

Against this backdrop, the concept of “heat” warrants attention. Heat stress refers to a state in which the body is placed under physiological load by exposure to high-temperature environments. It has been shown to cause not only heatstroke but also a variety of health problems, including the worsening of cardiovascular and respiratory diseases, mental illness, and reduced labor productivity. In addition, heat has been reported to affect not only absenteeism but also presenteeism—reduced productivity while at work due to diminished concentration and efficiency. The International Labour Organization (ILO) reports that heat associated with climate change is an important occupational health issue that seriously affects workers’ health, safety, and productivity.

Moreover, population aging and the spread of non-communicable diseases (NCDs) are making people more susceptible to the adverse effects of heat. Beyond older adults and people with underlying conditions, those who refrain from using air conditioning out of concern over electricity costs, those living in homes with insufficient insulation, and workers engaged in outdoor or high-temperature tasks are also considered particularly vulnerable to heat. For these reasons, heat is not merely a meteorological phenomenon but a health issue deeply connected to social factors such as the living environment and economic circumstances.

Global Efforts to Address Heat

Internationally, the World Health Organization (WHO) promotes the development of Health National Adaptation Plans (HNAPs) as a health-sector adaptation strategy for responding to the diverse risks that climate change poses to health. An HNAP is a medium- to long-term national strategy that enables the health sector to work across domains to address a wide range of climate-related health risks, such as the spread of infectious diseases and changes in water and food security. In practice, some countries have developed independent HNAPs specific to the health sector, while others integrate health-sector adaptation measures within a whole-of-government National Adaptation Plan (NAP); the format varies by country. For the purposes of this column, such national plans are referred to as “National Health Adaptation Plans (HNAP-equivalent).” Among the risks addressed, heat is one of those for which action is especially urgent, and as a concrete implementation plan, countries are developing Heat-Health Action Plans (HHAPs) and building early warning systems. In 2008, the WHO Regional Office for Europe set out the basic concept of the HHAP—a comprehensive action plan for preventing heat-related health harm. Within HNAPs, heat is positioned as one of the principal climate-related health risks, and the HHAP is used as a representative adaptation measure for that risk. Today, HHAPs are being developed and introduced in coordination with climate change adaptation and health policies of each country and region.

In 2015, the WHO and the WMO jointly published “Heatwaves and health: guidance on warning-system development,” providing concrete guidance on developing early warning systems for heatwaves. In 2016, the WHO, the WMO, and the U.S. National Oceanic and Atmospheric Administration (NOAA) jointly established the Global Heat Health Information Network (GHHIN), which promotes technical support and information sharing among countries. This network remains active today under WMO and WHO leadership, strengthening the bridge between science and policy through the establishment of regional hubs (such as Southeast Asia and South Asia) and the provision of various tools. Furthermore, in 2026 the WHO Regional Office for Europe published the second edition of its HHAP guidance, presenting eight core elements for implementing effective heat countermeasures: (1) governance, (2) heat-health warning systems, (3) populations at increased risk, (4) communication, (5) health system resilience, (6) reducing heat exposure, (7) heat-health surveillance, and (8) monitoring, evaluation, and learning. These serve as a practical framework for planning, implementing, and continuously improving heat countermeasures.

Building on these international frameworks, countries around the world are undertaking efforts adapted to their own circumstances. In the United Kingdom, for example, the UK Health Security Agency (UKHSA) operates a Weather-Health Alerting System. This system issues alerts for high temperatures and other extreme weather that are expected to affect health. Action guidelines corresponding to each alert level are also in place so that relevant organizations—such as medical institutions, care facilities, and local governments—can take appropriate responses. Through such mechanisms, weather information is connected to concrete actions to protect health.

In France, the 2003 European heatwave resulted in a large number of casualties, prompting the strengthening of measures against heat-related health harm. Today, the National Heatwave Plan (Plan National Canicule) is updated annually, setting out the alert system for heatwaves and measures to protect vulnerable people such as older adults and patients with chronic diseases. To strengthen adaptation to heatwaves, improvements to the urban environment and enhancements to housing performance are also being pursued as part of climate change adaptation.

In India, against the backdrop of severe heatwave damage in recent years, heat countermeasures are being advanced. The Ministry of Health and Family Welfare has developed a National Action Plan on Heat-Related Illness to promote the prevention and early detection of heat-related illnesses and to strengthen response systems. In addition, the city of Ahmedabad has introduced a Heat Action Plan that includes an early warning system using weather forecasts, public awareness activities, training for health workers, and stronger coordination among relevant organizations. What these efforts have in common is that they do more than issue alerts—they build mechanisms that connect alerts to concrete actions.

Taking these national efforts into account, the state of development of the National Health Adaptation Plans (HNAP-equivalent) and Heat-Health Action Plans (HHAP-equivalent) in the G7 countries can be summarized as follows (Table 1). Although the names and positioning of the plans differ by country, they serve as concrete examples of implementation plans within their health-sector adaptation strategies.

 

Table 1. National Health Adaptation Plans (HNAP-equivalent) and Heat-Health Action Plans (HHAP-equivalent) in the G7 Countries

Country

National Health Adaptation Plan
(HNAP-equivalent)

Heat-Health Action Plan
(HHAP-equivalent)

Japan

Climate Change Adaptation Plan

Action Plan for Heatstroke Countermeasures

United States

HHS Climate Adaptation Plan

National Heat Strategy (led by NIHHIS, the National Integrated Heat Health Information System)

United Kingdom

National Adaptation Programme

Adverse Weather and Health Plan (operated by UKHSA)

France

National Climate Change Adaptation Plan (PNACC: Plan National d’Adaptation au Changement Climatique)

National Heatwave Plan (Plan National Canicule)

Germany

German Strategy for Adaptation to Climate Change (DAS: Deutsche Anpassungsstrategie an den Klimawandel)

Heat Protection Plan for Health (Hitzeschutzplan für Gesundheit)

Italy

National Climate Change Adaptation Plan (PNACC: Piano Nazionale di Adattamento ai Cambiamenti Climatici)

National Plan for the Prevention of the Health Effects of Heat (Piano operativo nazionale per la prevenzione degli effetti del caldo sulla salute)

Canada

National Adaptation Strategy / Health of Canadians in a Changing Climate

Heat Alert and Response Systems (HARS); no unified federal plan, led by provinces and municipalities

Note: “HNAP-equivalent” is not limited to formal, independent HNAPs; it is a convenient summary of the national-level plans and policies responsible for health-sector climate change adaptation in each country. Some countries have developed plans specific to the health sector, while others integrate the health sector within a whole-of-government National Adaptation Plan (NAP).

Note: In the federal states of Canada and Germany, it should be noted that planning is centered at the provincial/state and municipal levels rather than a unified national HHAP. Plan names in each country may also have been revised or renamed in recent years.

 

Efforts within Japan

In Japan too, the effects of climate change have driven an increase in extremely hot days and in the number of people transported by ambulance due to heatstroke, making heat countermeasures an important public health challenge. According to the Fire and Disaster Management Agency of the Ministry of Internal Affairs and Communications, the number of people transported by ambulance for heatstroke nationwide from May to September 2025 was 100,510—the highest since surveys began in 2008. In 2021, the “Action Plan for Heatstroke Countermeasures” was formulated, setting the goal of holding annual heatstroke deaths to 1,000 or fewer and shifting to a marked downward trend. In the same year, the Ministry of the Environment and the Japan Meteorological Agency began nationwide operation of the Heatstroke Alert in April, establishing a mechanism to raise heat awareness and call for vigilance against heatstroke when dangerous heat is forecasted. In 2023, the Climate Change Adaptation Act was amended, and in addition to conventional adaptation measures, the response to increasingly severe heatstroke was substantially strengthened. From 2024, operation of the Heatstroke Special Alert also began. Because the health impacts of heat extend not only to daily life but also to the workplace, the Ordinance on Industrial Safety and Health was amended in June 2025, requiring employers involved in work with heatstroke risk to establish reporting systems and to develop response procedures to prevent cases from becoming severe. Furthermore, in April 2026 the Japan Meteorological Agency defined days with a maximum temperature of 40°C or higher as “kokushobi” (extreme-heat days).

In parallel with government efforts, collaboration among companies and research institutions is also advancing. In 2026, the Industry-Government-Academia Consortium for Heatstroke Countermeasures led by the National Institute for Environmental Studies was established. The consortium aims to promote the sharing of technologies and knowledge on heatstroke countermeasures and to advance the social implementation of measures through collaboration among diverse actors.

Thus, while Japan has been strengthening its heat countermeasures in recent years, developing legislation and challenges in operationalizing alert systems remain. In particular, in aging societies such as Japan, heatstroke countermeasures for older adults are an important challenge. Older adults are considered to be at high risk of heatstroke because they become less able to perceive heat and their thermoregulatory function declines. It has also been pointed out that socially isolated people are more susceptible to the health impacts of heat, so strengthening support systems is important. Therefore, beyond individual awareness-raising, efforts that link with local communities and welfare services are needed. In Japan, the Action Plan for Heatstroke Countermeasures (now the implementation plan) can be positioned as the domestic heat countermeasure plan corresponding to the internationally promoted HHAP. However, the two differ in scope and structure in the following ways. First, Japan’s plan sets the reduction of heatstroke deaths and ambulance transports as its primary goals, centering on acute-phase harm prevention such as issuing alerts based on the Wet Bulb Globe Temperature (WBGT) and designating cooling shelters. By contrast, the HHAP presented by the WHO targets not only heatstroke but also the worsening of cardiovascular and respiratory diseases, impacts on mental health, and reduced labor productivity, and is designed as a framework that comprehensively incorporates the eight core elements noted earlier: governance, warning systems, support for vulnerable populations, communication, health system resilience, reducing heat exposure (urban planning, improved housing performance, etc.), surveillance, and monitoring, evaluation, and learning. Second, Japan’s plan centers on individual awareness-raising and management measures by employers; elements such as coordination with urban planning, housing policy, and energy policy, and individualized outreach to vulnerable populations, are still developing relative to the level that the HHAP calls for. Third, surveillance systems for continuously monitoring the overall health impacts of heat, and monitoring and evaluation mechanisms for assessing and improving the effectiveness of measures, are also expected to be further strengthened going forward. Compared with the internationally promoted HHAP, Japan is expected to further enhance comprehensive heat countermeasures spanning weather, health, welfare, and urban planning. In addition, although air-conditioner ownership is high, the problem of “energy poverty”—in which people refrain from using cooling due to rising electricity prices and an inclination towards economizing—has also been pointed out. Going forward, comprehensive heat countermeasures are needed that include not only the development of alert systems but also support for vulnerable populations and improvements to the living environment. It is also important to promote context-specific measures that take into account regional differences in climate and demographics.

Conclusion

As climate change advances, the health risks posed by heat are expected to further escalate. Yet heat is not only about heatstroke; it has wide-ranging impacts on health, society, and the economy—increased mortality risk, exacerbation of chronic diseases, effects on mental health, the living environment and energy poverty, and reduced labor productivity. Planetary health is a way of thinking that regards human health and the health of the planet as mutually interconnected. Heat is an example that illustrates how climate change affects people’s health. To respond to such challenges, it is important for multiple sectors such as environment, welfare, urban planning, and energy policy to collaborate and advance measures that comprehensively address the health impacts of heat. There is a need to build mechanisms, like those embodied in the WHO’s HHAP, in which multiple sectors work together to advance prevention, preparedness, response, and evaluation. It is also important to clearly position such HHAPs within the broader HNAP for health-sector climate change adaptation, aligning them with responses to climate-related health risks other than heat. At the same time, steadily advancing adaptation measures to protect health while also integrating mitigation measures that curb the progression of climate change itself is important for realizing a sustainable society.

 

References

 

Authors

Tomoka Shimatsu (Intern, Health and Global Policy Institute)
Aina Ozawa (Intern, Health and Global Policy Institute)
Mako Mihira (Intern, Health and Global Policy Institute)
Gail Co (Program Specialist, Health and Global Policy Institute)
Joji Sugawara (Vice President, Health and Global Policy Institute)

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