Japan advises effective heatstroke prevention methods amid rising summer temperatures

Medical experts warn that popular cooling gadgets such as adhesive cooling sheets and neck coolers do not prevent heatstroke because they only create a sensation of cold without helping the body dissipate internal heat. Dr. Kei Nagashima, a physician specializing in heatstroke prevention, stresses that the key is to enable the body to release heat to the environment.

Data from the Japan Meteorological Agency show a sharp increase in extremely hot days: in 2015 Tokyo recorded 11 days above 35 °C, rising to 25 days in 2025, while Nagano went from 7 to 26 days. From 2026, days exceeding 40 °C will be classified as “severe heat days.”

Professor Shinya Hayasaka of Tokyo City University recommends specific bathing practices to avoid overheating. He advises a full‑body soak in water around 38 °C with carbonated bath salts for 10–15 minutes, which improves blood flow without raising core temperature. Cooler showers (30–35 °C) are suggested after intense heat exposure, and overly hot water should be avoided as it can increase body temperature and stress the cardiovascular system. These measures aim to reduce the risk of heatstroke and summer fatigue as Japan endures prolonged heatwaves.