The thermal stress along a marathon course in Tokyo is evaluated using a radiation balance model. The wet-bulb globe temperatures (WBGTs) for runners and spectators are calculated based on the surrounding building and tree geometries using the Solar LongWave Environmental Irradiance Geometry model. Analysis is conducted in terms of summer days in August 2018, which was during the hottest summer in the past 5 years. The WBGT classification for runners along the outward leg (until around 14 km) reaches the “Warning” level (WBGT = 26.5°C) despite of the many shadows on the street in the early morning (until 0645 JST). The WBGT increases around the Imperial Palace because the road has a sky view factor of over 95%, and no obstacles to make shadows on the street at around 0750 JST. The WBGT classification for runners reaches the level of “Severe warning.” For spectators, the difference of average WBGT from the runners are about 0.1°C although the difference could be significant locally due to partial shading on a road side.

使用辐射平衡模型评估东京马拉松赛道上的热应力。运动员和观众的湿球地球温度（WBGT）使用Solar LongWave环境辐照度几何模型根据周围的建筑物和树木的几何形状进行计算。根据2018年8月的夏季进行分析，这是过去5年中最热的夏季。尽管清晨街道上有许多阴影（直到0645 JST），但沿外腿（直到14 km）的跑步者的WBGT分类达到“警告”级别（WBGT = 26.5°C）。WBGT在故宫周围增加，因为这条道路的天空视野系数超过95％，并且在0750 JST左右没有障碍物在街道上造成阴影。运动员的WBGT分类达到“严重警告”级别。对于观众而言，跑步者的平均WBGT差异约为0.1°C，尽管该差异可能会由于路边的局部阴影而在局部显着。