The lingering danger of heat

Another alarming fact that was revealed on the TV Asahi Morning Show's report on heat stroke, is that heat effects linger. According to a joint study by the University of Tokyo and the Tokyo Metropolitan Medical Examiner’s Office once daytime temperatures begin to exceed 31°C, the risk of heat‑related death doesn’t just rise for that day - it lingers. 

Their research revealed the effects of the heat can remain in the body for four to five days, increasing vulnerability long after the hottest afternoon has passed. Even more alarming is how sharply the danger climbs: for every 1°C increase above that threshold, the risk becomes 1.5 times higher. It’s a steep curve, and it shows how quickly “a little hotter than usual” can turn into something genuinely dangerous.

Japan’s summers are no longer something we can shrug off. This kind of research makes it clear that heat isn’t just a momentary discomfort - it’s a cumulative stress on the body. Staying cool, hydrated, and aware of indoor temperatures isn’t just good practice; it’s essential protection.