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Many experts skeptical about measures to beat the heat during Tokyo Olympics

Officials of the Tokyo Metropolitan Government and other authorities measure the surface temperature of a sidewalk sprayed with water in the capital's Chiyoda Ward on Aug. 13, 2018. (Mainichi)

TOKYO -- Many experts doubt the effectiveness of measures that organizers of the 2020 Summer Olympics and Paralympics in Tokyo are considering to defy the heat, such as installing devices to generate mist and using cool air fans.

In an experiment carried out since July, a study team made up of researchers from the University of Tokyo and others sprayed mist from the top of a 2.8-meter-tall platform set up on the premises of its Komaba campus in Meguro Ward, Tokyo, when the temperature was 35 degrees Celsius.

The mist did give a sensation of coolness, but it is obviously not enough to beat the scorching heat in the middle of summer.

During the Tokyo Games, the organizing committee is considering installing mist-generating devices near the entrance to the new National Stadium, the main venue. However, Takaaki Matsumoto, professor of environmental physiology at Chukyo University School of Health and Sport Sciences, dismisses the measure as being just like "sprinkling water on parched soil."

In a preliminary experiment conducted by the University of Tokyo team, the surface temperature of people's skin declined by only 1 degree after being exposed to mist for 10 minutes. However, the experiment has proven that spraying mist is hardly effective in reducing deep body temperatures that are related to heatstroke.

Ryozo Ooka, professor of urban energy engineering at the University of Tokyo, points out that spraying mist "only marginally helps to alleviate heatstroke."

During the Olympics and Paralympics, many spectators could be forced to wait outside venues for indoor sports for a long time under the scorching sun. The organizing committee is considering setting up tents with cool air fans inside near where spectators will line up while trying to limit the waiting time to about 20 minutes. However, the waiting time for popular events could far surpass that limit.

Osamu Kashimura, professor of environmental physiology at Tokyo University of Agriculture, points out such a measure will not be effective enough to prevent heatstroke.

"Since the time when spectators can use tents is limited, we can't expect the measure to be effective as a whole," Kashimura says. "Those vulnerable to heatstroke such as elderly people should be given priority in using tents."

The Tokyo Metropolitan Government and other authorities are insulating pavements on roads that are part of the route for the marathon and race walk events. However, such pavements can be counterproductive for spectators.

Eiko Kumakura, assistant professor of urban environment engineering at Tokyo Metropolitan University, says insulating pavements "could increase sensory temperature," noting that such pavements reflect sunlight more than asphalt.

Akio Hoshi, professor of health science at Toin University of Yokohama, urges spectators to protect themselves by drinking enough water.

Makoto Yokohari, professor of urban engineering at the University of Tokyo, advises people not to go to the venue if it is too hot. "If you feel the scorching heat is unbearable, you should consider choosing not to go and watch events," he says.

(Japanese original by Yuka Saito, Tokyo Science & Environment News Department)

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