Using a value chain to develop a new warning service from scratch - epidemic thunderstorm asthma risk forecasts in Victoria, Australia

In November 2016, an unprecedented epidemic thunderstorm asthma event in Victoria, Australia, resulted in many thousands of people developing breathing difficulties in a very short period of time. It caused ten deaths and created extreme demand across the Victorian health and emergency services. Because of the link between thunderstorm asthma and grass pollen allergies, a new early warning system for epidemic thunderstorm asthma (ETSA) risk was developed and operates during grass pollen season (October-December) each year. The warnings are delivered through a partnership between the Victorian Department of Health, the Bureau of Meteorology, the University of Melbourne, and AirHealth Lab.

Value chain concepts were instrumental in the design of the warnings. Starting with the user needs, namely health sector preparedness and community safety, the partners worked backwards to determine the value chain of necessary capabilities (communication, risk assessment, hazard prediction, modelling, observations) and information flows that would be needed to provide a thunderstorm asthma warning service. This process highlighted gaps in knowledge of the hazard, and the need to develop capability to measure and predict grass pollen to support the thunderstorm asthma warnings. The value chain also helped define the partners’ roles and responsibilities in delivering the warnings.

Focused effort by the partners enabled the thunderstorm asthma warning system to be implemented in time for the 2017 pollen season, accompanied by a full range of community, health and emergency sector awareness raising and education activities. The system uses a categorical risk-based approach, combining operational forecasting of gusty winds in severe thunderstorms with forecasts of high ambient grass pollen concentrations, which together generate the risk of epidemic thunderstorm asthma. This system now provides the first daily epidemic thunderstorm asthma risk warning service in the world that covers a wide area, and integrates into the health, ambulance and emergency management sector.

At the end of each season the partners meet to review the performance of the warning system, including its ability to predict the hazard (i.e. the weather and grass pollen conditions associated with thunderstorm asthma risk) and the impact (unusually high numbers of people presenting to hospital emergency departments with asthma symptoms). The warnings show modest skill in discriminating between days with and without health impacts.

This cyclical review process has led to continuous improvements in all aspects of the warnings system. These include more accurate grass pollen forecasts based on machine learning, progressive installation of automated pollen monitors to replace manual pollen counting, near real time detection of asthma spikes in hospital emergency departments based on natural language processing, and use of value-oriented metrics to tune the weather and grass pollen thresholds to optimize warning performance.