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As summer starts to scorch Japan, some advice on preventing heatstroke

A man walks while wiping off sweat amid extreme heat in Tokyo's Chiyoda Ward on Aug. 2, 2022. (Mainichi/Kotaro Yoshida)

TOKYO -- Summery days are set to continue early across Japan beginning on May 16, according to the Japan Meteorological Agency (JMA).

    Daily high temperatures of 25 degrees Celsius or over will hit the country, particularly in western Japan, on May 16, while in places such as Tokyo and Nagoya, highs are expected to hit 30 degrees or above on May 17 and 18. With the sudden change in weather, people will need to take precautions to avoid heatstroke.

    While many suffer from heatstroke during July and August, caution needs to be taken starting around May, when people are not yet used to the heat. The Mainichi Shimbun spoke with an expert to find out ways to prevent the illness.

    According to data collected by the Fire and Disaster Management Agency, an external agency of the Ministry of Internal Affairs and Communications, 71,029 people were transported to hospitals for heatstroke last year between May and September. This was the third-highest figure since surveys began in 2008. In May alone, 2,668 were taken to hospitals for heatstroke and four died.

    The human body takes measures such as sweating and increasing blood flow to relieve excess heat. But in this early part of the hot season, it cannot sweat very well.

    "During this time of year when people are not yet used to the heat, people should do things such as going shopping during the morning or evening and using sun umbrellas," is the advice offered by Hiroshi Nose, a specially appointed professor of Sports Medical Sciences at the Shinshu University Graduate School of Medicine with in-depth knowledge about ways to prevent heatstroke.

    One reason the elderly suffer from heatstroke more than young people is their difficulty sensing when they are thirsty. People should get into the habit of drinking one or two cups of water in the morning, even when one does not feel thirsty.

    Other measures can be taken now, before things really heat up. According to sources including the 2023 edition of "Ways to prevent heatstroke in daily life," published by the Japanese Society of Biometeorology this April, people are advised to aim for around 30 minutes of moderate exercise per day from May to June. For example, by alternating between walking at a brisk and leisurely pace at three-minute intervals. "This is an easy measure for the middle-aged and elderly to take. After keeping this up for about two weeks, the body will adapt to the heat and begin to sweat more easily," professor Nose pointed out.

    Additionally, drinking fluids containing protein and sugars, such as milk, immediately after exercise increases blood flow and helps the body regulate its temperature. People who don't like milk can try alternatives such as yogurt or cheese. Professor Nose added, "To prevent heatstroke, it's important to think and take action."

    (Japanese original by Mikako Shimogiri, Lifestyle, Science & Environment News Department)

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