A woman holds an umbrella while another uses a portable fan as pedestrians cross an intersection under the sun in Tokyo's Shibuya district on July 9, 2026. (Kyodo)

TOKYO - The risk of death from heatstroke rises when the daytime high exceeds 27.1 C, a joint study by the Tokyo metropolitan government and the University of Tokyo has found, with the research team urging people to actively use their air conditioners as midsummer approaches.

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