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)External Link

IGEM has also monitored the progress of the implementation of the recommendations from the reviewExternal Link

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:


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

Reviewed 11 March 2023

Your health: Report of the Chief Health Officer, Victoria, 2018

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