NHK has learned that a study suggests an anti-heat measure for next year's Tokyo Olympics and Paralympics may have an effect opposite to that intended.
The Tokyo Metropolitan and central governments are applying a special coating to more than 100 kilometers of roads, including the Olympic marathon course, to reduce surface temperatures.
A group of researchers at the Tokyo University of Agriculture led by Professor Osamu Kashimura compared normal and coated roads on sunny days this month and in July to evaluate the coating's effectiveness.
The results show surface temperatures on the special roads were about 10 degrees Celsius cooler than those on the normal roads.
But when measured at the heights of 50, 150 and 200 centimeters, average temperatures on the coated roads were higher.
When the sunlight was especially strong, the average temperatures were about 1.5 degrees higher. The difference exceeded more than 3 degrees at some times of the day.
Professor Kashimura says the special coating lowers surface temperatures by reflecting sunlight, but the reflected sunlight makes people standing on the road feel hotter.
Kashimura points out that there's a risk of heatstroke among athletes and spectators of the Olympics. He says authorities should examine the effectiveness of the coating and take necessary steps to prevent heatstroke.
Land ministry officials say athletes who ran on the coated roads reported that they felt cooler. The officials say they consider the measure effective based on various assessments.