Heatstroke Prevention: Caution Needed Even around End of Rainy Season

Editorial

16:38 JST, June 29, 2025

Heatstroke occurs when the body loses water and its ability to regulate temperature declines. Although heatstroke is often associated with midsummer, many people also suffer from it in May and June. This is attributable to the fact that it is more difficult for people to regulate their body temperature because high humidity means that sweat evaporates less.

Sufficient caution is needed for this type of heatstroke, which is typical in the rainy season.

In addition, during the period immediately after the end of the rainy season, the number of people suffering from heatstroke usually increases rapidly, as the body has not yet fully become used to the heat. Consciously acclimatizing to the heat by engaging in light exercise, such as walking, is considered effective.

In recent years, about 90,000 people a year have been transported to a hospital by ambulance due to heatstroke in Japan, and more than 1,000 people died. Many of those who died from heatstroke were in their 70s and 80s. Elderly people are unlikely to be aware of the heat and their thirst, and they develop heatstroke without realizing it even at home.

To prevent heatstroke, it is important to drink fluids frequently and use air-conditioning sufficiently. It is crucial that people around the elderly check on them and encourage them to use air-conditioning.

The Industrial Safety and Health Law has been revised to require companies to strengthen measures against heatstroke in the workplace, starting this month. It can be said that the measure is necessary to protect the health of workers because extreme heat is becoming common.

Employees with symptoms such as headaches, dizziness or unsteadiness should be detected promptly and allowed to rest. If their condition appears abnormal, they should be taken to a medical facility immediately. Workplace managers must establish such procedures and communication networks in advance.

Deaths due to heatstroke are conspicuous in industries where people often work under the blazing sun, such as construction, manufacturing and transportation, but indoor workplaces are also at risk.

It is likely important for employers to provide spacious break rooms where air conditioning and ways to hydrate are available, as well as to introduce well-ventilated work clothes and uniforms.

With the summer vacation period approaching, the risk of heatstroke will rise further along with an increase in children’s sports and outdoor activities. Sports organizations have increasingly introduced rules to suspend activities when the wet bulb globe temperature (WBGT) — known as the heat index — which is calculated from factors such as temperature and humidity, exceeds a certain threshold.

Ingenuity is called for, such as introducing “cooling times” during sports events to cool the body from the inside with sherbet-like beverages. Consideration also should be given to holding games in the morning or evening hours when it is cooler, or moving events to the winter season, without sticking to traditional practices.

(From The Yomiuri Shimbun, June 29, 2025)