Japanese researchers have conducted a series of tests along the marathon course, which will be used during the 2020 Tokyo Olympics, to assess ways of protecting spectators and athletes from heatstroke.
The tests were conducted on Thursday by experts from Hosei University and the Japan Weather Association.
The experts flew a drone equipped with a camera, which is capable of measuring temperatures with infrared light, along the marathon course in central Tokyo. It glided at an altitude of 150 meters.
The drone flew repeatedly at 30-minute intervals to measure the surface temperatures on ordinary paved roads, and on those paved with a special coating.
The data will be used to determine how the temperatures changed, and how effective the coating was at keeping the surface temperatures from rising.
The researchers also recorded surface temperatures around the clock, from the rooftop of a building about 120 meters high, to determine how the temperatures changed over time.
In another test, students wearing instruments, which measured their heart rates and how much they sweat, were asked to stand in the sun, in the shade, and in an area where some water had been sprinkled.
Associate Professor Shun Kawakubo of Hosei University said that studying ways to protect against heatstroke will save lives before, during, and after the Olympic Games. He also said that effective measures can be developed by studying the effects of high temperatures on the human body and on roads.