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Heat stroke measures

Last update date August 14, 2020

Let's be careful about heat stroke

At this time that is the hottest in one year, attention is necessary for heat stroke regardless of the night and day.
"New lifestyle" accompanied with appearance of new coronavirus infectious disease is shown and we will spend under the different living environment this summer until now, but will keep in mind for the heat stroke prevention more than before while preventing enough infectious diseases.
It is heat stroke that may be life-threatening when symptom gets worse, but can prevent by appropriate prophylaxis.

Point of heat stroke preventive action in "new lifestyle"

○ It might become at increased risk of heat stroke when we wear mask while temperature, humidity of the summer is high.
 Therefore, we take off mask in consideration of risk of heat stroke when we can secure enough distance (at least 2m or more) with people outdoors
○ When we wear mask, we avoid work and campaign for strong load and will keep hydration in mind diligently even if not thirsty
  u. In addition, it is necessary we take off mask appropriately at place to be able to take distance with neighboring people enough, and to take a break.
○ It is necessary to secure ventilation by ventilation fan and window opening even in air conditioner to prevent new coronavirus infectious disease.
  In this case as indoor temperature rises, let's coordinate temperature setting of air-conditioner for the heat stroke prevention diligently.
○ The everyday temperature measurement, healthy check are effective as well as new coronavirus infectious disease in preventing heat stroke.
  When we felt that we are ill-conditioned, we will take a rest at home without overdoing it.
○ We will do elderly person, child, watch, calling to person with a disability that are easy to suffer from heat stroke while avoiding 3 dense (crowd, closeness, sealing).
Heat stroke preventive action (flyer A4 one side) of Ministry of the Environment, Ministry of Health, Labour and Welfare making 2020 (PDF: 719KB)
Heat stroke preventive action (flyer A4 both sides) in Ministry of the Environment, Ministry of Health, Labour and Welfare making "new lifestyle" (PDF: 809KB)
About point to keep in mind of taking an action preventive heat stroke of Ministry of the Environment, Ministry of Health, Labour and Welfare making 2020 (material for details) (PDF: 113KB)

About precedent conduct of "heat stroke caution alert" (trial)

Ministry of the Environment and the Meteorological Agency carry out announcement of "heat stroke caution alert" (trial) as contribute to heat stroke prophylaxis, is effective, disseminating information newly in Tokyo and 8 prefectures (Tokyo, Ibaraki, Tochigi, Gunma, Saitama, Chiba, Kanagawa, Yamanashi, Nagano) of the Kanto Koshin district from July 1, 2020 to October 28, the same year.
"Heat stroke caution alert" (trial) is some point in the prefecture, and heat index (WBGT) is announced at around 17:00 of the day before and around 5:00 a.m. on that day when thing more than 33 degrees Celsius is predicted. As we deliver "extreme high temperature forecast" of disaster prevention information E-mail in standard same as heat stroke caution alert, in Yokohama-shi, we can obtain information quickly by registering here.
In addition, we have "friend addition" of LINE official account of Ministry of the Environment and can obtain information in LINE. When alert was announced, I would like thorough heat stroke prophylaxis more than usual that we usually carry out.

The details about "heat stroke caution alert" (trial) this (the outside site) (Ministry of the Environment website)
Preventive action (PDF: 244KB) at the time of Ministry of the Environment, the Meteorological Agency making heat stroke caution alert announcement
Delivery item of disaster prevention information E-mail is this place
About information distribution of heat stroke caution alert (trial) utilizing LINE application this (the outside site) (Ministry of the Environment press release material)

The heat stroke prevention point from before

Supply of 1 moisture, salt "will take moisture even if we do not feel drought"

●Let's take moisture diligently
⇒When we felt drought, internal moisture has been already short. Let's take moisture diligently even if we do not feel drought.

●When we sweated a lot, let's take moderate salt
⇒Salinity of body falls down when we drink only water and tea as 2-3 grams of salt per 1 liter is included in sweat when we broke a lot of sweats and may cause muscle cramp.
We take appropriate quantities of salt including sports drinks, and let's do.
If it is sports drinks containing ion drink and 40-80 milligrams of sodium (in 100 ml), we can take appropriate quantities of salt with moisture.

●Quantity to drink in once will make around one cup of glass (150-200 ml)
⇒We subdivide appropriate amount, and let's drink without drinking lot at a time.

●Even if I am in the room where air-conditioner worked for and do not sweat, moisture of body is lost
⇒We do not feel relieved when we turn on air-conditioner and will supply moisture.
In addition, let's mind family.

●Moisture is not enough only by taking alcoholic beverage including beer
⇒As alcoholic beverage raises diuretic effect, moisture might be lost more and more by body.
Let's supply not only alcohol but also moisture properly.

"Let's have attention to 2 clothes to clothes which can miss heat outside"
●Let's keep air permeable good clothes in mind
⇒As size of the neck is part with much release of heat, it will prevent you from tightening.

●Let's devise with imminent thing to prevent rise in temperature
⇒Used ice pack and bamboo blind, round fan, and squeezed around neck coolly; get wet, and wind up towel, and let's devise.

●We absorb sweat, and let's wear clothes of air permeable good material
⇒Material chooses cotton or hemp, and color will choose whitish color not black, too.

●Let's avoid direct rays of the sun when going out
⇒Temperature under outdoor hot weather becomes higher than temperature of weather forecast. When we appear outdoors, we put on hat and will place parasol.

"We make ventilation better, and let's temperature-control invention to spend coolly in three rooms using air-conditioners"
●Let's put thermometer, hygrometer which we are easy to look at in room
⇒We put thermometer, hygrometer and will check diligently.

●Let's shut out direct rays of the sun with bamboo blind and curtain
⇒Because effect of air-conditioner may get worse by solar light to enter at window even if we use air-conditioner, let's cut off direct rays of the sun with curtains.

●Let's use electric fan and air-conditioner
⇒On temperature and humid day, impossible power saving will use electric fan and air-conditioner moderately without doing.

●Let's make ventilation better
⇒We open window and door facing each other, and let's spend without shutting up room when we do not use air-conditioner.

●Let's sprinkle in the evening
⇒Temperature falls to take heat around the surface of the earth. It will be good to perform using the second use water such as rainwater or the remainder water of bath.

Health care of around 4th "will be sweaty by moderate exercise"
●It is important to usually sweat
⇒We take a lot of moisture and raise diuretic effect and can regulate temperature by writing sweat more and more.

●Let's exercise routinely
⇒We exercise, and let's increase muscles to increase internal fluid volumes. It is important to supply with moisture, salt well before exercising.

●Poor physical condition is to watch out
⇒Let's be careful to become easy to suffer from heat stroke at the time of lack of sleep and hangover, poor physical condition including slight cold.

●WBGT level will have reference, too
⇒WBGT level is index of heat calculated by temperature, humidity, radiation (emission) heat,
The standard value depending on the degree of exercise and work is set.
Observation level and expected numbers are published in homepage (heat stroke prevention information site) (the outside site) of Ministry of the Environment.

Heat stroke that Part 5 is working on occurs frequently
●When we play sports indoors, let's supply with ventilation and moisture, salt
⇒We open window and door indoors, and let's make ventilation better. In addition, let's supply moisture, salt lost by exercise.

●There is big difference in heat tolerance by individual.
⇒When when is tired, need more sleep, such as a cold when is ill-conditioned, let's stop exercising forcibly.

Symptom of heat stroke

Disease severity


Slight illness

Dizziness, muscular pain, mass sweat※

Medium grade symptom

Headache, feeling unpleasantness, nausea, vomiting, lassitude, despondency


Motor deficit, hyperthermy of disturbance of consciousness, convulsions, hands and feet

※ As there is not sweat if heat stroke becomes severe and becomes dry skin, what we do not judge only from sweat is important

Emergency measure

●Evacuation to cool environment
⇒Let's rest quietly in bed at good place of ventilation in the room where air-conditioner worked for or the shade.

●Stripping and cooling
⇒Let's do invention to lower temperature by cooling with ice pack sending wind to bathe in water which takes off clothes, and misses heat.

●It supplies with moisture, salt
⇒Let's refrain from impossible intakes to be in danger of aspiration on vomiting.
Alcohol, caffeine add to volume of urine, and let's wait as dewatering may advance.
Oral supplementary water liquid (thing which dissolved salt and glucose in water) and sports drinks which we can supply with salt lost for sweat are most suitable.
It becomes indication of conveyance to medical institution not to be able to drink water by oneself.
Let's cope early before not becoming seriously ill.

Let's be careful about such points

Let's mind change of everyday physical condition
It becomes a factor that custom for physical condition and heat of the day causes heat stroke. We will usually mind change of oneself and neighboring physical condition.

Elderly person and child, person with a disability, child with a disability require attention in particular

●It is elderly people of patients with heat stroke quite with half 65 years or over.
⇒As elderly person has decreased sensory function for heat and water deficit, and adjustment function decreases because we correspond to heat, attention is necessary.

●Consideration to where it is difficult to report poor physical condition including small child is necessary.
⇒As for the small child, adjustment function of temperature has not developed enough yet, and it is said that it is difficult to report poor physical condition.
It is important to mind change of rather famous child.

When when we were at a loss, we were in trouble

●Emergency consultation center
#When 7119 is not connected; ... 045-232-7119
●We want to look for emergency care engine
Information for consultation, emergency care engine at the time of sudden illness

Heat stroke measures material in the summer event

In late years there is concern about influence on health because days that come to have 30 degrees Celsius or more temperature increase, and we see in the long term, and there is temperature in upward trend through the year.
We made leaflet which gathered up prophylaxis to hold safely based on heat stroke in particular being easy to occur at event in the summer the outdoors. Please inflect in conjunction with check list.
●Heat stroke measures leaflet for the summer event holding
Heat stroke measures leaflet for companies
Downloading this (PDF: 746KB)

●Heat stroke measures check lists such as the summer events at the time of holding
Heat stroke prevention check list (Fire Bureau making)
Downloading this (PDF: 864KB)

Collection of links

[Yokohama institute for health]
Let's prevent heat stroke (heat stroke, sunstroke)
Heat stroke information

[City of Yokohama, Fire Bureau]
Heat stroke related information

[Ministry of the Environment]
Heat stroke prevention information site (the outside site)
Live broadcast and prediction (the outside site) of heat index (WBGT)
Downloading (the outside site) of the spread enlightenment material
Heat stroke environmental health manual (March, 2018 revised edition) (the outside site)

[Ministry of Health, Labour and Welfare]
"Let's drink water for health"; campaign (the outside site)
Labor hygiene measures in the workplace [heat stroke prophylaxis] (the outside site)
For the heat stroke prevention (the outside site)

[the Ministry of Internal Affairs and Communications Fire and Disaster Management Agency]
Heat stroke conveyance information (nationwide) (the outside site)

[the Meteorological Agency]
To protect the body from heat stroke [including predictive information, weather forecast of temperature]; (the outside site)
Abnormal weather early warning information (the outside site)
The Kanto Koshin district one month forecast (the outside site)

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Inquiry to this page

Health and Social Welfare Bureau health security department health business section

Telephone: 045-671-2451

Telephone: 045-671-2451

Fax: 045-663-4469

E-Mail address [email protected]

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