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Heat stress hazard forecasts for endurance events

Research project

Short description

The Gothenburg Urban Climate Group undertakes ongoing interdisciplinary research on the influence of weather on medical emergencies during endurance events such as marathons and half-marathons, and evaluating screening tools for assessment of heat stress. We aim to develop a predictive tool and recommendations that can improve participants’ safety and the utilization of healthcare resources. In this project, we are developing heat stress forecasts based on numerical weather prediction models. We are currently running the forecast system to collect data for evaluation, and we provide a Preview of the outputs for selected locations (mainly in Sweden) as part of this evaluation effort.

About the project

City marathons are nowadays important events in many communities, creating an exciting experience for participants and spectators, while contributing to multiple health benefits. City marathons attract a large number of participants. Considering training activities and other health related preparation, these events have become an important contributor to public health in Sweden.

Although a number of health benefits come with running, a share of the runners may suffer from health incidents. Weather is a critical extrinsic factor in determining the risk at endurance events. A pilot study on the impact of weather on heat stress hazard under seven Gothenburg half marathons (2010-2016) found collapses increased with increasing heat stress.

The wet-bulb globe temperature index, WBGT, is a heat stress index used to decide whether specific races should run or not. However, the WBGT index is not based on physical theory. Alternatives are include the physiological equivalent temperature index (PET) and the universal thermal comfort index (UTCI), which model thermal conditions in a physiologically relevant way. In the pilot study, the PET index had the strongest correlation with rates of ambulance-required assistances and collapses, followed by the UTCI, with the WBGT index showing substantially poorer correlations. This suggests that PET and UTCI are useful indices of heat stress hazard for endurance events, potentially more useful than WBGT.

Although PET and UTCI cannot be measured directly, they can be calculated from meteorological data and local geographical information. Further, PET and UTCI can be calculated from numerical weather forecast model outputs, as we are developing in this project.