Thunderstorm asthma

This fact sheet provides guidance on how to minimise the risk of asthma attacks triggered by thunderstorms.

Minimising the risk of asthma attacks triggered by thunderstorms.


On the evening of Monday, 21 November 2016, a thunderstorm asthma event occurred in Melbourne that caused unprecedented numbers of people to develop asthma symptoms and seek emergency treatment at the same time. It resulted in nine deaths and is the largest event of its kind on record globally.

Thunderstorm asthma events are difficult to predict. They are infrequent and don’t happen every year.

In NSW, minor thunderstorm asthma events have happened during the grass pollen season (typically October to December) in regions such as Wagga Wagga and northern NSW, as well in the ACT.

Whole grass pollen grains are relatively large and can cause hay fever symptoms in some susceptible people. Thunderstorm asthma is thought to be triggered when a thunderstorm involves rapid changes in wind, temperature and humidity, which can cause pollen grains to burst into tiny particles that get past the nose and throat and penetrate deep into the lungs.

Anyone can experience asthma symptoms during a thunderstorm asthma event – even people who don’t have a history of asthma. It can affect people living in metropolitan, regional or rural areas.

However, those at increased risk are people with:

  • a history of asthma
  • hay fever (allergic rhinitis), particularly seasonal hay fever
  • an allergy to grass pollen.


Asthma symptoms include:

  • wheezing
  • breathlessness
  • coughing
  • chest tightness.

Preparing for a thunderstorm asthma event at your workplace

The weather can’t be controlled but there are a number of things persons conducting a business or undertaking (PCBUs) and workers can do to be prepared for possible thunderstorm events.

PCBUs should:

  • know which of your workers are asthmatic. Arrange for workers – particularly outdoor workers – to have their asthma management plans updated to include their regular medications and any advice for thunderstorm asthma
  • check on and communicate with these workers regularly about their respiratory status – and more frequently during changing weather conditions
  • check the pollen forecast app daily
  • check weather forecasts for possible thunderstorms – particularly on days with a high or extreme pollen count
  • be prepared for unexpected weather changes that may trigger an asthma attack
  • where possible, have workers indoors with doors and windows closed until the storm front has passed
  • ensure a trained first aider is onsite at all times.

Workers with asthma have a personal responsibility to proactively manage their asthma condition.

Most people can achieve good asthma control by using their inhalers every day (even if feeling well), having regular check-ups with their doctor and a current asthma management plan.

They should also:

  • always have their prescribed reliever medications on them when at work
  • know the signs of worsening asthma and remain alert to them. Act on the development of any asthma symptoms
  • check pollen levels where they live, work and when travelling interstate
  • stay indoors with doors and windows closed on high-pollen and windy days, and during and after a thunderstorm until the storm front has passed. If there is air conditioning, set it on ‘recirculate’
  • have their medications and asthma management plans regularly reviewed and updated by their doctor, and seek urgent medical review if they are concerned about their asthma
  • wear respiratory protection during rapidly changing weather conditions (involving wind, temperature and humidity).

Managing an asthma attack

If a worker with no history of asthma starts experiencing asthma symptoms, medical treatment should be sought immediately.

If an asthmatic worker thinks they are having an asthma attack, they should follow the instructions in their asthma management plan. Their asthma symptoms can be severely increased during thunderstorm asthma events and can be life threatening.

If there are signs that a worker’s condition is deteriorating, urgent medical care must be obtained.

Signs of rapid deterioration are that the person:

  • finds little or no relief from their reliever inhaler
  • is unable to speak comfortably
  • their lips start turning blue
  • they collapse into unconsciousness.

Further information

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