Value Village ／ Health
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Every summer in Japan, around 90,000 people are taken to hospital by ambulance for heatstroke (熱中症, netchūshō). Many newcomers picture young people exercising outdoors. In fact, more than half of those taken to hospital are older people, and the single most common place it happens is the home. If this is your first Japanese summer, the humidity makes the heat harder on the body than the thermometer suggests. Here are the basics of prevention, and how to judge symptoms when they appear.
| Item | Figure (guide) |
|---|---|
| Ambulance transports | About 90,000 a year (May–September, Fire and Disaster Management Agency; 91,467 in 2023) |
| Age | About 55% of those transported are 65 or older |
| Where it happens | The home is the most common place, at about 40%. Then roads, outdoor workplaces and sports grounds |
| Deaths | Around 1,000–1,500 a year (Vital Statistics). Over 80% are 65 or older; in most indoor deaths the air conditioner was not in use |
| Heat index (WBGT) | 25 and above: caution. 28 and above: severe caution (stop strenuous exercise). 31 and above: danger (avoid going out). At 33 and above a "Heatstroke Alert" (熱中症警戒アラート) is issued |
| Indoor environment | Room temperature 28°C or below, humidity 60% or below as a guide. Older people feel heat less, so place a thermometer-hygrometer and judge by the numbers |
| Fluids | 1.2 L a day besides meals, as a guide (Ministry of the Environment). If you sweat heavily, add 0.1–0.2% salt (sports drinks, oral rehydration solution — 経口補水液, keikō hosui-eki, sold at drugstores) |
| Grade | Symptoms | Response |
|---|---|---|
| Grade I (mild) | Dizziness, light-headedness, muscle pain or cramps, heavy sweating | Move somewhere cool, loosen clothing, cool the neck, armpits and groin, take fluids and salt. If no improvement, go to a medical facility |
| Grade II (moderate) | Headache, nausea, vomiting, feeling weak, unable to concentrate | Go to a medical facility. If the person cannot drink unaided, call 119 |
| Grade III (severe) | Confusion, odd replies, convulsions, unable to walk straight, hot body | Call 119 at once. Until the ambulance arrives, cool the whole body (wet towels plus a fan; ice on the neck, armpits and groin) |
[Verify] The number of transports, the age breakdown and the share by location change each year. Update to the most recent Fire and Disaster Management Agency data at publication. Check the WBGT categories against the Ministry of the Environment's Heat Illness Prevention Information site.
The most common place is the home, and more than half of those taken to hospital are older people. Rooms with the windows shut, sleeping hours and the time after a bath all need care.
By the time you feel thirsty, mild dehydration has already begun. Older people feel thirst less, so drinking at set times is the reliable way.
When the room is hot, a fan only moves hot air around. Both the Ministry of the Environment and the Ministry of Health, Labour and Welfare urge people "not to hesitate to use the air conditioner". Put life before the electricity bill.
Heavy sweating loses salt too. Drinking large amounts of water alone can dilute the salt in your blood and make you unwell. On days you sweat a lot, take salt as well.
Headache, nausea and exhaustion are signs of moderate heatstroke, the stage at which you should see a doctor. If the person responds slowly when spoken to, or cannot drink unaided, call 119. A wrong judgement here can cost a life.
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https://www.wbgt.env.go.jp/
https://www.fdma.go.jp/disaster/heatstroke/post3.html
https://www.mhlw.go.jp/seisakunitsuite/bunya/kenkou_iryou/kenkou/nettyuu/nettyuu_taisaku/
⚠️ Editorial note: the source URLs above were identified by search. Our working environment cannot reach go.jp domains, so the contents have not been checked against the text. Verify every source before publication and record who checked it and when.
What we share here are ideas and everyday practices passed down among people living in Japan, together with general information drawn from public sources. They are not official recommendations, and they are not professional instruction. Practices vary between households and regions.
This is general information. Results vary from person to person and depend on your own conditions and surroundings.
Please decide for yourself, using your own judgement, whether any of this suits your situation. We cannot accept responsibility for any damage, loss or injury arising from following this article.
This article is not meant to diagnose or manage any specific medical condition. If you are worried about your health, see a doctor rather than relying on your own judgement.
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