The heat and humidity that descends on the Japanese capital after the rainy season has been a concern since it won the bid to host the Games in 2013.
Doubts over Tokyo’s claim in its 2020 pitch that “mild” weather in July and August would provide athletes with the ideal sporting environment were underlined in 2019, when the International Olympic Committee pressured organisers to move the marathon and race walking events to the cooler climes of Sapporo, 800km (500 miglia) north of Tokyo.
The first time Tokyo hosted the Olympics, nel 1964, organisers made the decision to move the “summer” Games to the autumn, when temperatures are comfortably lower.
But athletes competing this year face potentially the hottest Olympics on record, with high temperatures combining with brutal humidity to make every moment spent outdoors an endurance test.
As Tokyo residents were warned not to exercise outdoors, beach volleyball players practising at Shiokaze park complained that the sand was too hot for their feet, prompting staff to hose down the playing surface while athletes waited in the shade.
Olympic organisers have introduced measures they say will protect athletes from the worst effects of the heat, including cooling tents, mist fans and ice cream for volunteers.
The environment ministry’s colour-coded scale warns residents when to avoid regular or heavy exercise. Early on Tuesday afternoon, the ministry reported that the wet bulb globe temperature – which combines temperature, humidity, wind and solar radiation measurements – stood at 31.8 degrees, prompting a “danger” warning. The WBGT is forecast to drop into the upper 20s over the next three days, tuttavia.
The ministry recommends that sports activities should be stopped when WBGT exceeds 31 degrees, but it is unlikely that the same standard will apply to Olympic events. It issued 13 “no exercise” advisories from late July to early August last year – the same timeframe as this year’s Olympics – according to the Kyodo news agency.
The ban on domestic spectators means Japanese sports fans will follow the action from the comfort of their air-conditioned homes, but there is concern that an expected rise in heatstroke cases could place additional pressure on medical services already stretched by Covid-19 infections and the vaccination rollout.
Giappone’s summer heat can pose a serious threat to health, especially among its large population of older people. Nel 2019, più di 71,000 people sought emergency care for heatstroke, con 118 deaths during the June-September period. L'anno scorso, when the pandemic meant there were fewer people out and about, there were still 65,000 cases and 112 deaths.
“Holding the Games during July and August … was a serious issue even before the coronavirus pandemic,” Haruo Ozaki, the chairman of the Tokyo Medical Association, told reporters this month.
“There are still high risks of heatstroke at events such as competitive walking, triathlon and beach volleyball.”
While the pandemic has forced many athletes to arrive only days before their events, others have had time to acclimatise. They include the Australian softball team, who arrived for their training camp in early June and will open the sporting action on Wednesday against Japan in Fukushima, where the forecast is for a high of 37C but, mercifully, plenty of cloud cover.
Agence France-Presse contributed reporting.