Department of Health

Epidemic thunderstorm asthma is thought to be triggered by an uncommon combination of high pollen levels and a certain type of thunderstorm, causing a large number of people to develop asthma symptoms over a short period of time. 

2016 thunderstorm asthma event

This phenomenon occurred in Victoria on the evening of Monday 21 November 2016 and led to thousands of people developing breathing difficulties in a very short period of time. 

While other events have been recorded in Melbourne and in other parts of the world, the November 2016 event was unprecedented in size, severity and impact, and was the largest incident of its type ever recorded in the world.

In the 30 hours from 6 pm on 21 November, there was a 672 per cent increase in respiratory-related presentations to Melbourne and Geelong public hospitals (3,365 more presentations than expected based on the three-year average). 


Tragically, the event also led to 10 deaths, which have been investigated by the State Coroner. 

The response to the November 2016 epidemic thunderstorm asthma event was reviewed by the Inspector-General for Emergency Management (IGEM)

IGEM has also monitored the progress of the implementation of the recommendations from the review

Thunderstorm Asthma Program

Since the November 2016 event, the department has worked closely with a wide range of stakeholders to develop and implement a comprehensive Thunderstorm Asthma Program to minimise the impact that any future epidemic thunderstorm asthma events may have on the community and the Victorian health system. 

As part of the Program, the department has:

  • implemented a public health campaign and education programs for the Victorian community and health professionals 
  • updated its public communications and warnings including integration with Victoria's warning system
  • developed expert clinical guidelines to identify and manage those at increased risk
  • revised the State Health Emergency Response Plan and improved how we plan, communicate and work with our health services and emergency management sector partners during emergencies
  • hosted an epidemic thunderstorm asthma symposium with experts from across Australia
  • published an extensive epidemic thunderstorm asthma literature review, and published a detailed assessment of the known environmental conditions and the health impacts of the event
  • implemented a Real-time Health Emergency Monitoring System to alert the department to significant demands on public hospital emergency departments and ensure early responses to actual or potential health emergencies
  • built and implemented the first Victorian epidemic thunderstorm asthma forecasting system.


Department of Health and Human Services 2017, Response to the November 2016 thunderstorm asthma event.

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Epidemic thunderstorm asthma is thought to be triggered by an uncommon combination of high pollen levels and a certain type of thunderstorm

Reviewed 04 August 2022


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