MEXT’s Health and Hygiene Information Websitefor Schools for Foreign Students

Prevention of Heat-Related Illness in School Activities


The Education Policy Bureau and the Elementary and Secondary Education Bureau of the MEXT had issued the notification as an attachment on April 28, 2023.
We do appreciate if you can use this material as an appropriate reference source to assess heat-related illness risks optimally so as to prevent heat stroke in school educational activities.

The Office for a Professional Platform of Health and Hygiene Environment in
Schools for Foreign Students provided by MEXT (mediPhone, Inc)
Tel: 050-3187-8114 (Multilingual consultation service)


Tentative translation

This notification summarizes precautions to prevent heat-related illness in school educational activities. Heat-related illness can occur even in a period with a moderate temperature (25°C to 30°C), thereby, all related parties should take appropriate actions to avoid health hazard for elementary, junior high, and high school students.

Preventing Heat-Related Illness in School Educational Activities

Kanako Asato
The director of the Gender Equality, Cohesive Society Learning and Safety Division of
the Education Policy Bureau, MEXT

Yuichi Tokiwagi
The director of the School Curriculum Division of the Elementary and
Secondary Education Bureau, MEXT

We appreciate your continuous efforts for reducing heat-related illness risks to prevent heat stroke in each school every year. Unfortunately, there were more than 3,142 heatstroke cases under the control of schools in 2022 school year. Considering a recent climate change and an incidence of heat illness, we must initiate taking appropriate measures even in a period with moderate temperature (25°C to 30°C) and properly assess potential heat-related illness risks using Wet Bulb Globe Temperature (WBGT).

In this school year, schools will plan and conduct a wider range of activities than those in last year. We summarize precautions to remind each school and school owners/administrators about them. We do hope you will take appropriate actions to prevent heat-related illness.

We wish to add that we have been sharing this information with the Japan Medical Association so that they can respond to you, school owners/administrators when you seek their help about heat-related illness.

"The Act of Partial Amendment to Climate Change Adaptation Act and the Environmental Restoration and Conservation Agency Act" was established on April 28 2023 at the 211th ordinary session of the Diet (this will come into force on the day specified by Cabinet Order within a year after promulgation, excluding the provisions of Heat Illness Prevention Action Plan.).

We will announce additional information on heat illness prevention measures based on the Act soon.


1.Maintenance of an Optimal Environment to Prevent Heat-Related Illness

Heat-related illness has a potential risk of being life-threatening, though it is preventable by maintaining an optimal environment. Please pay attention to the following points and encourage all related parties to prevent heat-related illness in students.

  • Encourage students to drink adequate volume of fluids before starting activities, and promote fluid and salt intake as needed.
  • Promote students to hydrate themselves and consume salt during and after activities.
  • If symptoms suggesting of any heat exhaustion/stroke symptoms are noted, please take appropriate measures such as fluid and salt replenishment, reducing body temperature, transferring to the hospital as quickly as feasible.
  • Most cases of heat-related illness under the control of the school were observed during physical education or sports activities. While, some cases had occurred in non-sports club activities and indoor class activities, and when students were traveling to and from school. Moreover, heat exhaustion is likely to develop when individuals fail to calibrate heat tolerance, such as in early seasons with increasing temperature or on the days drastically getting hotter, or in weather conditions with moderate temperature (25°C to 30°C) but much humidity and weather with other risk factors. Considering these facts mentioned above, regardless of the extent of school curriculum, please take appropriate measures early to prevent heat-related illness.
  • Air-conditioning systems have been increasingly installed in school facilities. Each school should use such systems; in addition, consider the variability in air-conditioning equipment between classrooms, special-purpose classrooms, and a gymnasium. Depending on installation/non-installation of air-conditioners in activity locations, activities have to be planned.
  • Combination of enhancing air-conditioning, heat-insulating properties, airtightness and necessary ventilations is effective for improving an indoor environment. While referring to "Examples of establishing eco-schools" (March 2020), please take measures such as using sunshades to protect students from the sunlight to facilitate an optimally ventilated environment.
  • Children left on school bus are likely to suffer from heat-related illness, resulting in life-threatening condition. Preschools must pay careful attention to such a potential risk of heat illness events and ensure monitoring where children are located, to prevent leaving children inside the school bus. As an outcome, Japanese government has supported schools to install safety systems in the school bus as a device to prevent human error through 2022 via a second supplementary budget. Preschools are recommended to have completed installation of safety devices by the end of June as much as possible. In addition, prior to completion of installation of the safety devices, please make sure to take all necessary preventative actions such as preparing and using a children's boarding checklist in school bus to ensure that no child is left inside a school bus.
  • For wearing a mask in a school, COVID-19 Infection Control Manuals and Guidelines for Schools describes that "In school educational activities, students, teachers, and staff basically do not need wear masks" and "Infants are not required to wear masks." Accordingly, each school should respond to each cases properly from the viewpoint of heat illness prevention.

2.Making Judgements to Conduct/Suspend School Activities

Anticipating suspension of activities in scorching weather to prevent heat illness, each school is recommended to specify the suspension criteria and an evaluator in a crisis management manual beforehand and share the information among school staff/teachers. To assess the risk of heat illness, Wet Bulb Globe Temperature (WBGT), one of the indices representing the heat stress, should be available.

You can check measured and estimated WBGT indices in each region on "Heat Illness Prevention Information" presented by the Ministry of the Environment. This information website also updates the Heat Stroke Alert issued by the Ministry of the Environment and Japan Meteorological Agency ("Heat Stroke Alert" is information that calls attention to dangerous heat and encourages people to take actions to prevent heat illness when the risk of heat illness is predicted to be extremely high (when the WBGT heat stress index forecast is over 33). This information release was started on April 26 2023.)

Also, the Ministry of the Environment and the Ministry of Education, Culture, Sports, Science and Technology prepared "Guidance About Developing a Guideline for Heat Illness Measures in Schools" together in May 2021, which helps school owners/administrators such as local boards of education to formulate and revise guidelines on heat illness measures for schools.

Please refer to the information and make judgements appropriately to conduct/suspend school activities.

3.Instructions as to Heat Illness Prevention among Students

To prevent heat-related illness, schools should give adequate instructions to students depending on their growth and development levels so as to allow them to regulate their health condition by themselves.

Please note the following points of instructions to students and also refer to "School Security Materials; Safety Education in Schools Fostering 'the Power to Live'" (revised by the Ministry of Education, Culture, Sports, Science and Technology in March 2019).

  • Wear a hat/cap and dress lightly during hot weather
  • Stay hydrated during exercise and take breaks
  • Check own health condition before exercise
  • Communicate among students to stay hydrated, and please call the attention of school staff/teachers immediately while feeling any health abnormalities

4.Managing Summer Vacation

Schools should appropriately determine a period of summer vacation in accordance with related provisions specified in reference document No. 2, referring to (1) and (2) as follows.

(1)Each school owner/administrator and school should decide to extend a summer vacation period or plan temporary holidays in summer as well as to shorten the period of winter vacation and the end/start of a school year vacation as needed, based on weather conditions and installation/non-installation of air-conditioners in school facilities (classrooms, special-purpose classrooms, and a gymnasium) upon due consideration to ensure the ‘health status’ of students.
At that time, use reference materials described in "reference items" at the end of this notification to make judgements based on school and local situation.

(2)Please take into consideration that "Under an emergency disaster and other urgent situation" specified in Article 63 of the Enforcement Regulations of the School Education Law (1947 Ordinance of the Ministry of Education No.11) include any cases requiring responses to prevent heat-related illness.

[Reference items]

○ The Ministry of the Environment
・"Heat Illness Prevention Information" website

・"Heat Illness Environmental Health Manual 2022" (revised in March 2022 by the Ministry of the Environment)

・Launching "Heat Stroke Alerts" in fiscal year 2023

・The cabinet decision on the bill to partially amend the Climate Change Adaptation Act and the Act on the Environmental Restoration and Conservation Agency

・Guidelines to assess and review "Crisis Management Manual" in schools

・Formulation of "Guidance About Developing a Guideline for Heat Illness Measures in Schools "

・School Security Materials: Safety Education in Schools Fostering "the Power to Live" (revised in March 2019)

・Support programs on safety and security measure for children (subsidies for school bus repair)

・Examples of establishing eco-schools

○ Japan Sport Council
・Heat illness prevention (Accident prevention measures in schools)