Summer in Japan is not a fun prospect. While there are various things to look forward to — fireworks, beach visits and the Bon holidays among them — this quarter of the calendar is marked by one thing above all: the weather. Almost a month of the season is spent under the pulverizing humidity of tsuyu (the rainy season).
Even more humidity follows the endless gray skies and downpours. “Record high” temperature news has become a running theme for Japan since 2018, when Kumagaya, Saitama Prefecture, clocked a record 41.4 degrees Celsius — matched in Hamamatsu, Shizuoka Prefecture, last year. Cities throughout Japan, including Tokyo, now experience consecutive days of 35-plus degrees; these heatwaves see reporters soliciting vox pops from passersby on TV news — “Atsui desu ne?” (“Hot, isn’t it?”) Yes, indeed it is.
This sort of heat is dangerous. In 2019, over 12,000 people nationwide were hospitalized with heatstroke (necchūshō in Japanese). While preventing heatstroke could be as simple as keeping the air conditioning running day and night, that’s not necessarily the only thing you can do (nor should it be).
Chilling at home
Any walk in July or August is a recipe for severe sweat, but air-conditioned establishments provide heavenly respite, like palatial refrigerators. Such is the power of AC, and it’s the first tool we have in the fight against heatstroke at home.
Hanako Okada, a spokesperson for the Heat Illness Prevention Communication Project, an initiative devised by The Japan Empowerment Consortium, says that even a room not exposed to direct sunlight poses a risk of heatstroke. She suggests measuring the room temperature and making sure it stays at 28 C or lower.
“As for the air conditioner, set the wind direction so that the cold air does not hit you directly,” Okada says. “When used in combination with an electric fan, you’ll feel cooler at the same temperature.”
But with air conditioning and fan usage accounting for an estimated 10% of global electricity demand (and estimates from the International Energy Agency indicating energy needs for cooling will triple by 2050), it’s worth looking for greener alternatives to cooling your home.
“The temperature rise in your room can be suppressed by using a ‘green curtain’ that grows plants such as gōya (bitter gourd) and kyūri (cucumber) on the outside of your building,” says Hiroaki Igarashi, from the public relations office of the Japan Weather Association, which also runs the Heatstroke Zero site. Guides on how to set up your own green curtain abound; nets (admittedly plastic) for your chosen plants to climb can be purchased for around ¥1,000. Additional privacy is an added perk.
For something more low maintenance, Igarashi recommends awnings. Either sudare — the catch-all term for bamboo or reed blinds stitched together that hang outside windows — or yoshizu, which tend to be larger and attach from the eaves down to the ground outside the window. “These can shut out up to 80% of the sun’s heat,” he says. Just make sure to set them up where the sun hits your window.
But for those extra hot and humid days, when no amount of shading will help and there’s no breeze to warrant having the door open for ventilation, it’s time for a multipronged, holistic solution. “By using an air conditioner, a fan and a dehumidifier, you can keep the room cool and the humidity low,” Igarashi says.
“There’s no such thing as ‘you only have to do this one method,’” Okada agrees. “So it’s best to think of it in terms of behavior, housing and clothing.”
You may already have your household affairs in order when it comes to keeping cool. But avoiding heatstroke doesn’t stop at what you can control inside.
When your body temperature rises, you sweat: a normal way to release heat from the body. But in a hot, humid environment, that doesn’t work so well. As you continue to sweat, you become dehydrated and your body temperature rises sharply, which can result in heatstroke. This generally occurs when temperatures exceed 25 C, Okada says, with particularly dangerous symptoms, even death, occurring at 30 C and above.
“Heatstroke can happen anytime, anywhere and to anyone, depending on the conditions,” Igarashi says. “Temperature is not the only cause of heatstroke. It’s caused by three main factors: environment, body and behavior.
“You need to be especially careful about heatstroke when the temperature is high, the humidity is high, when you’re not feeling well, your body is not accustomed to the heat or you are exercising hard.”
Wearing a hat, using a parasol or simply sticking to the shade when you’re out and about are all ways to minimize the chances of overheating. Okada also recommends wearing usugi (light clothing); Igarashi expands this to “clothing made of materials that are highly breathable and quick-drying.”
Bathing is another option — or simply wiping your body down with a damp cloth (especially at the nape of your neck, underarms and tops of thighs). Used in conjunction with a fan, it’s a good way to lower your body temperature. Go manual with a sensu (folding fan) or uchiwa (handled fan) to save on electricity bills.
Japan is nothing if not emphatic about food, and for the heat of summer there are some culinary customs that can help cool your body. It may seem obvious, but it begins with chilled beverages.
“Cold drinks are a good way to cool your body directly,” Okada says. “Beverages absorb (into the body) well at 5 C to 15 C and have a large cooling effect.” Many favor chilled mugicha (roasted barley tea) for its health benefits; practically all supermarkets stock giant mugicha tea bags that you can steep in large containers of water overnight. Kakigōri (shaved ice) is a sweeter option that also fits the bill.
“In addition, cucumbers and watermelons, which are in season in summer, contain a lot of water and are recommended. It’s a good idea to chill it and eat it,” she adds.
Grilled unagi (eel) slathered with tare may not seem like a heat-buster, but it’s a summer staple and is traditionally eaten on Doyo no Ushi no Hi, or Day of the Ox (midsummer, which falls on July 28 this year). Though nutritious, medicinal effects of eel are unproven. But food that increases the appetite, as the heat tends to decrease it, is valued during summer, too — shichimi (“seven flavor” seasoning) is thought to do just that. Ginger is another good option (try this ginger pork), as are make-ahead, light meals.
When contending with fan positioning at home, or jealously guarding your spot in the shade of a traffic light pole as you wait to cross the road, it’s easy to forget that summers have historically been hot in Japan. It must have been a very sticky affair in the Edo Period (1603-1868) and beyond, but Edokko (old-time Tokyoites) had some tricks up their sleeve. Many are still relevant today.
One of these pieces of wisdom, Okada says, is uchimizu. Literally “striking water,” this involves sprinkling, splashing or otherwise inundating the balcony, garden or the pavement immediately outside one’s home with water. She recommends doing this “in the morning or evening, rather than in the daytime,” so the water doesn’t evaporate right away. For over a decade, uchimizu has been a government-recommended practice.
Other pearls of sagacity that have dripped into the wider consciousness include a good fright. Though maybe more of a distraction than anything else, spooky stories are thought to induce chills. Above all, summertime Edo was a world of smoke, heat and mosquitos: patience was key.
For information, advice and alerts about heat stress across the country, visit the Ministry of Environment’s dedicated website at www.wbgt.env.go.jp/en.
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