%0 Journal Article %T Microclimate Variations between Semienclosed and Open Sections of a Marathon Route %A Paulina Wong %A Poh-Chin Lai %A Melissa Hart %J Advances in Meteorology %D 2013 %I Hindawi Publishing Corporation %R 10.1155/2013/287934 %X The Hong Kong Standard Chartered Marathon, held annually, is one of the most popular international marathon events. Its primarily urban environmental setting characterized by high-density urban areas, semienclosed tunnels, and suspension bridges, together with the herds of runners, has an influence on the microclimate along the marathon course. This study focused on assessing and comparing variations in temperature and vapour pressure (vis-¨¤-vis relative humidity) against the crowd of runners, or the herd effects, in two different environmental settings along the marathon course: semienclosed (a tunnel) versus open space (a suspension bridge). A series of small iButtons were deployed at strategic locations along the course to undertake minute-by-minute measurements of temperature and relative humidity. It was found that herd effects of varying degrees were present in both semienclosed and open settings. Various environmental differences also played a role in ameliorating or amplifying the climatological effects of the herd of runners. Our study suggests that microclimate variations in different environmental settings and crowd conditions could have an impact on runners. This new knowledge can inform the design of marathon routes. It also establishes the feasibility of employing the iButton logging sensors for widespread deployment and monitoring of meteorological situations. 1. Introduction More than 500 marathons are held annually around the world, with competitors ranging from elite marathon runners to recreational athletes [1]. Each marathon is challenging by the way of its course design and the environment through which the route passes. The increased popularity of marathons has prompted research on the effects of weather conditions on runners. Previous studies have been mainly based on statistical analyses of past marathon data by quantifying effects of weather conditions on the performance or completion times of the runners [2¨C6]. The most noticeable human effect is in the microclimates found in the heavily built-up areas, and this localised microclimate may become more pronounced when runners are tightly bunched in moving packs or ˇ°herdsˇ± [7, 8]. In addition to anthropogenic impacts on the microclimate from the herds of runners, course terrain, landscape, urban configurations, and meteorological conditions will contribute to the microclimate along a marathon route [9], which may influence level of human thermal comfort [10] and performance of each individual runner. However, there is a lack of studies exploring possible impacts of microclimatic %U http://www.hindawi.com/journals/amete/2013/287934/