TOKYO >> A number of people fell ill recently due to high temperatures at a rowing test event for the 2020 Tokyo Olympic and Paralympic Games, despite ongoing preparations to prevent heatstroke during test events nationwide.

A marathon swimming test event at another site, meanwhile, was moved up by several hours as a countermeasure against heat.

These challenges spotlight concerns about the weather during the actual Games less than a year away.

“I want to watch the Olympic races a year from now, but this extreme heat (feels life-threatening),” said a spectator from Saitama on Aug. 11, her face covered in sweat. She was in attendance to watch the rowing competitions.

The Sea Forest Waterway, site of the rowing contest, was completed in May. But to reduce construction costs, only about half of the grandstand, with a capacity of 2,000, is covered by a roof. That day, areas directly exposed to sunlight reached 92.6 degrees by 10 a.m.

At the venue, metropolitan officials distributed cooling packs and set up tents made with thermal barrier materials for spectators waiting for buses.

Despite all the efforts, one visitor suffered from apparent heatstroke and received medical treatment on site.

According to the Japan Rowing Association, 10 participating athletes felt ill, primarily during an awards ceremony that was held outdoors.

On the same day, a marathon swimming test event was held at Odaiba Marine Park in Tokyo. As water temperatures rose, the men’s race was moved up to start at 7 a.m. instead of 10 a.m.

FINA, an international federation that administers Olympic water sports competitions, stipulates that races must be held in water temperatures of 87.8 degrees or lower. But by 5 a.m., water temperature at the marine park had already reached 85.8 degrees.