【Table of contents】

  1. How to prevent heatstroke
  • 6 Points to prevent heatstroke
  • About wearing a mask in the summer
  1. Useful tips for heatstroke prevention

1.How to prevent heatstroke                                                     

Here are some points to prevent heatstroke.

For more information on the symptoms of heatstroke and how to deal with it, see「1-2 Heatstroke」.

The basics in preventing a heatstroke in daily life is suppressing dehydration and rising body temperature. To do so, it is important to avoid heat and stay hydrated.  

We have summarized the precautions, so let’s check them out together.

<6 Points to prevent heatstroke>

1)Avoid the heat!

 Dividing into 3 factors 「Action」「Home」「Clothing」, we will explain how to avoid the heat.


  1. Do not overdo it on a hot day
  2. Walk in the shade
  3. Take refuge in a cool place
  4. Take a break, do not work too hard, do not over do it 
  5. Use the weather forecast as a reference to consider the date of going out and event, avoiding hot days and times 



  1. Take advantage of air flow
  2. Block the sunlight from the window
  3. Use air conditioning equipment such as air conditioners and electric fans
  4. Use heat of vaporization(Sprinkle water in the evening)
  5. Block heat from outside


  1. Wear loose clothing
  2. Loosen collar for air vent 
  3. Utilize sweat absorbing・quick-drying or light・cool suits
  4. Avoid black materials that absorb radiant heat under the sun
  5. Use a parasol or a hat (Take off a hat occasionally to evaporate the sweat) 

2)Stay hydrated!

On hot days, we are sweating unknowingly. Even if you are working out or not, make sure to stay hydrated.

Humans do not feel thirsty when they are lightly dehydrated. Therefore, it is important to be hydrated before being thirsty or going to hot places. However, alcohol should be avoided. Alcohol will increase the amount of urine and excrete water in the body. 

1 Daily intake of water is recommended to be 1.2ℓ. Amount of water should match your amount of sweat. Therefore, if you are sweating heavily, supply water and salt.

You will be sweating during a bath and sleep, so drinking water after waking up and before and after taking a bath would be recommended to prevent overheating. . 

3)Be careful of hot days!

Heat stroke usually occurs from around May before the rainy season every year and attend to occur frequently from late July to early August after the rainy season.

Heat stroke is likely to be experienced when “you spend outdoors on a day when it becomes suddenly hot” or “travel from cool area to warm area”. To be able to sweat well, you need to 

adjust to the heat. Be careful on the following days and do not over do it.


『Source:Ministry of the Environment「Heat stroke environmental manual 2018」』

Be careful of these days
Starting to get hotSuddenly gets hotDay after a tropical night

4)Build your body for the heat!

Heat stroke is more likely to occur when your body is not used to the heat. As hot weather continues, your body gets accustomed to the heat. This is called heat adaptation. To obtain heat adaptation, you need to continue exercising (such as walking) for 30 minutes every day under “slightly hot environment” and “slightly straining yourself”.

Get into the habit of sweating from a daily walk, so that your body can overcome the summer heat.


5)Consider your physical strength and physical condition!

The cause of heat stroke can be affected by the physical condition of the day.  For example, if you are dehydrated or in bad health conditions, such as without meals, you should avoid going to a hot environment. If you have a cold, diarrhea, or hangover, you should be careful as you may be dehydrated. If you are obese, a child or the elderly, have decreased cardiopulmonary or renal function, or taking medication that affects autonomic nervous and circulatory function, be aware that you are more likely to have a heat stroke.

『Source:Ministry of the Environment「Heat stroke environmental manual 2018」』

Check columns for before working out and going to work
Is work or exercise commensurate with physical strength?
Are you already adapted to the heat?(After 3 days under hot environment)
Do you have any history of heat stroke?
Are you obese?
Are you taking any medication for chronic disease such as high blood pressure?
Did you sleep enough?
Did you consume an excessive amount of alcohol?
Are you hungover? 
Did you eat breakfast?
Are you feeling well?
Are you not dehydrated?

6)Watch out for each other in group activities!

Preventing heat stroke requires not only individual efforts, but also consideration of people around them. For example, if you work outside, taking a break frequently, replacing a worker to shorten the activity time per person is necessary.

It is especially important to protect the pace according to physical strength and health of the individual and not to over do it.https://3.bp.blogspot.com/-Qmda7JG63SY/WPsEENnqzKI/AAAAAAABD1o/lAiyCAkP_fcycSs_n4CLM09Nar1Bb_xWwCLcB/s800/sports_ouen_soccer.png

<About wearing a mask in the summer>

Masks are necessary from the viewpoint of preventing the spread of infectious diseases, but we must be careful when wearing them in the summer.Take note of the following points to prevent heat stroke.

    Be careful of wearing a mask in high temperature and humidity! Beware of your physical condition!https://4.bp.blogspot.com/-Gob19MXY9gM/UQJe7kIOrcI/AAAAAAAALJU/SemkME2AjZ8/s1600/checkbox_checked.png

    If you have enough distance with people outdoors(over 2m), take your mask off!https://4.bp.blogspot.com/-Gob19MXY9gM/UQJe7kIOrcI/AAAAAAAALJU/SemkME2AjZ8/s1600/checkbox_checked.png

    When you are wearing a mask, avoid burdened work and exercise, and keep enough distance with people and take off your mask and take a break! https://4.bp.blogspot.com/-Gob19MXY9gM/UQJe7kIOrcI/AAAAAAAALJU/SemkME2AjZ8/s1600/checkbox_checked.png


2.Useful tips for heatstroke prevention                                                    

We have explained points to prevent heat stroke, but this is the practical part. We have compiled the lists of heat stroke prevention that you can do yourself, so give it a try! 

    Check weather information and government reminders!https://4.bp.blogspot.com/-Gob19MXY9gM/UQJe7kIOrcI/AAAAAAAALJU/SemkME2AjZ8/s1600/checkbox_checked.png

High temperature caution information

When tomorrow or today’s highest temperature is expected to be higher than 35℃, there will be an announcement.

  • Japan Meteorological Agency 「High Temperature Caution Information」


Heat Index(WBGT)Ministry of the Environment

The heat index was proposed in the United States in 1954 for the purpose of preventing heat stroke. It is an index of temperature that uses 「temperature」「humidity」「radiant heat」 which affects human heat balance. Among them, humidity is the most important index. This is because sweat is hard to vaporize in places with high humidity, and the body’s ability to release heat is reduced, making it easier to cause heat stroke.

The units are shown in the same degrees as temperature in Celsius(℃). However, its value is different from the temperature. If heat index is over 28℃, the study has shown that more people are likely to have heat stroke.

It is possible to check the heat index for three days on the day, the next day, and day after tomorrow. You can also search in English, Chinese, and Korean.

  • Ministry of the Environment「Heat Stroke Prevention Information Site」

    Use the air conditioner wisely!https://4.bp.blogspot.com/-Gob19MXY9gM/UQJe7kIOrcI/AAAAAAAALJU/SemkME2AjZ8/s1600/checkbox_checked.png

Point① Temperature Setting

Aim at 28℃ room temperature when using the cooling. If the room temperature is low(below 24℃), and there is a huge difference between outside temperature and room temperature, it will be a burden on the body when entering and leaving the room. When you get home and feel that room is hotter than outside, open the window first to ventilate the room. Also, using sederes and green curtains can suppress the rise of the room temperature.

Point② Airflow

If you consider the air flow and air volume of the air conditioner, using a fan together, it will feel cooler even at the same temperature.


Point③ Sun’s rays

Cutting off the sunlight entering through windows by curtains, etc, and use the air conditioner effectively.

《How to use the air conditioner effectively》

  • Put into the effort of air flow that cold air does not hit the person directly for a long time.
  • Adjust the wind direction looper up to in the horizontal direction to circulate the cold air from top to bottom. 
  • If you feel a little hot, make the air volume stronger or use a fan rather than lowering the set temperature. 
  • If you are bothered by the wind, apply the wind of the fan to the wall or ceiling and use the bouncing of the air to soften the wind.
  • Clean the filter once every two weeks so that the function of the air conditioner does not decrease.https://3.bp.blogspot.com/-zCTm58V7_6s/UnXnNilafnI/AAAAAAAAaKM/aYWdhU_KUrI/s800/kaden_airconditioner.png

Utilize heat stroke prevention goods!https://4.bp.blogspot.com/-Gob19MXY9gM/UQJe7kIOrcI/AAAAAAAALJU/SemkME2AjZ8/s1600/checkbox_checked.png

There are many products that can reduce heats, and prevent heat stroke. It is also important to prepare in case of an emergency.


  • Salt candy
  • Cooling goods
  • Oral resuient solution 

・Contents above are created with references to sources shown below. If there is a change in the contents of the reference source, it may take some time to be reflected on to the site. Thank you for your understanding.


・Ministry of the Environment「Heat Stroke Prevention Information Site」


・Ministry of the Environment 「Heat Stroke Environmental Manual 2018」


・Japan Meteorological Agency 「To Protect Yourself from Heat Stroke」