Soaring temperatures in Japan have killed at least 57 people since late July, authorities said on Tuesday, highlighting the health threat to athletes and fans that Olympic organisers must tackle before next year's Tokyo games.
Temperatures have been stuck above 31 degrees Celsius (88 degrees Fahrenheit) in and around Tokyo since July 24, the date on which the summer games will open in Japan's capital next year.
More than 1,800 people were taken to hospitals in Tokyo between July 29 and Aug. 4, the Disaster Management Agency said on Tuesday.
Last summer, temperatures hit a record 41.1 degrees Celcius just north of Tokyo, which first hosted the Olympics in 1964. That year, the games were held in October to avoid the heat. Four years later, the Mexico City games were also moved to October.
Most summer games since 1976 have been held during the Northern Hemisphere summer due to international broadcasting and sports schedules, forcing Tokyo organisers to find ways to keep athletes and tens of thousands of fans cool and hydrated.
"Weather conditions were often organisers' challenges in past Olympic and Paralympic games. We also understand that top-tier competitions can sometimes be observed in cities with even tougher weather patterns than in Tokyo," said Masa Takaya, spokesman for the 2020 games.
The 2004 Athens Olympics and 2008 Beijing games were also held in cities known for their summer heat.
"In this respect, input and expertise from the IOC (International Olympic Committee) and the sports federation from their past experiences are extremely valuable," Takaya said.
Tokyo organisers are evaluating heat-fighting measures from mist sprays and ice packs to shaded rest areas and tents at security checkpoints.
"We will keep working closely together with the Tokyo Metropolitan Government, the national government and relevant stakeholders to ensure the successful delivery of the games," Takaya added.
Japanese summers are becoming increasingly hot, and the Japan Meteorological Agency (JMA) coined a new term -- "ferociously hot days" -- in 2007 due to the rising number of days with temperatures above 35 degrees Celcius.
Tomoyuki Kitamura, a JMA scientific officer, said Tokyo suffers from a "heat island effect", where concentrated heat in cities prevents them from cooling off at night.
The heat is made worse by a relative lack of shade in the Japanese capital, which is home to 9.2 million people.
As a result, the Olympic marathons will start at 6 a.m. local time next summer, an hour earlier than scheduled.