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Epidemic Thunderstorm Asthma

Protect yourself this pollen season, managing asthma and allergy matters. 

What is epidemic thunderstorm asthma?
Who is at risk of epidemic thunderstorm asthma? 
What can you do to be prepared?
What should you do if you are experiencing asthma symptoms?
More information and resources

What is epidemic thunderstorm asthma?

Asthma and hay fever symptoms increase every year during grass pollen season. There is also the chance of an epidemic thunderstorm asthma event.

Epidemic thunderstorm asthma events are thought to be triggered by an uncommon combination of high grass pollen levels and a certain type of thunderstorm, resulting in large numbers of people developing asthma symptoms over a short period of time. These events not only cause lots of people to become unwell but their sudden onset and potentially severe nature can put a strain on health services, with many people requiring medical support.

As epidemic thunderstorm asthma events are uncommon, the exact mechanism driving them is still unclear. One view is that pollen grains from grasses get swept up in the wind and carried for long distances. Some can burst open and release tiny particles that are concentrated in the wind just before the thunderstorm. These particles are small enough to be breathed deep into the lungs and can trigger asthma symptoms, making it difficult to breathe.

It is thought that the grass pollen grains and allergens are removed from the air by the rain from the thunderstorm.

Whole grass pollen grains are relatively large and can in some susceptible people cause irritation of the eyes, nose and throat, resulting in what is commonly known as hay fever.

On the other hand, the allergens released from burst grass pollen grains are small enough to get past the nose and throat and be breathed deeply into the lungs. Irritation here can trigger asthma symptoms such as: 

  • wheezing
  • breathlessness
  • a tight feeling in the chest; or
  • coughing

Research to better understand how epidemic thunderstorm asthma events occur is currently underway.

The important points about epidemic thunderstorm asthma events are: 

  • They are uncommon and are not responsible for the seasonal increase in asthma symptoms seen every year
  • They affect a lot of people all at once
  • They can affect people with asthma, people with undiagnosed asthma (i.e. people who have asthma symptoms but have not yet been diagnosed with asthma), those who have had asthma in the past, and people with hay fever who may or may not have asthma.
  • People with hay fever in south eastern Australia are likely to be allergic to grass pollen, and are therefore at increased risk of epidemic thunderstorm asthma.

When do epidemic thunderstorm asthma events occur? 

Thunderstorm asthma events don’t occur every year but when they do, they can happen during the grass pollen season in south-east Australia.

The grass pollen season varies across Australia however in south-east Australia it is typically from October through December.

Who is at risk of epidemic thunderstorm asthma?

Those at increased risk of epidemic thunderstorm asthma include:

  • People with asthma
  • People with a past history of asthma
  • Those with undiagnosed asthma (i.e. people who have asthma symptoms but have not yet been diagnosed with asthma)
  • People with seasonal hay fever (who may or may not  have asthma)

People with hay fever in south eastern Australia are likely to be allergic to grass pollen, and are therefore at increased risk of epidemic thunderstorm asthma.

Having both asthma and hay fever and poor control of asthma increases the risk further.

Most people with asthma can achieve good asthma control. This means that you:

  • Have asthma symptoms on no more than two days a week
  • Need your blue/grey reliever no more than two days a week, or even not at all
  • Experience no limitations on your activities due to asthma and
  • Don’t get any asthma symptoms at night or when you wake up

Take the Asthma Control Test today to find out your level of asthma control and visit your doctor for an asthma review.  

What can you do to be prepared?

What everyone should do? 

Everyone in south east Australia should be aware of the phenomenon known as epidemic thunderstorm asthma. While the environmental conditions that have resulted in previous epidemic thunderstorm asthma events are uncommon, they will reoccur in the coming years and it is important that everyone is prepared. It's important for everyone to know the symptoms of asthma and what do do if someone is having an asthma attack.. 

What should I do if I am at an increased risk?

  • Understand the epidemic thunderstorm asthma phenomenon
  • Have an asthma action plan (where advised by your doctor) and /or have practical knowledge of the 4 steps of asthma first aid
  • Have reliever medication appropriately available in grass pollen season and be aware of how to use it (ideally with a spacer)
  • Be alert to and act on the development of asthma symptoms as explained in your asthma action plan if you have one, or if you don’t, use asthma first aid 

Be aware of thunderstorm forecasts 

Particularly on HIGH or EXTREME pollen count days.

For those at risk, where possible it’s best to avoid being outside during thunderstorms during the grass pollen season – especially in the wind gusts that come before the storm. Go inside and close your doors and windows and if you have your air conditioner on, turn it to recirculate.

Never ignore asthma symptoms like breathlessness, wheezing and tightness in the chest 

Start Asthma First Aid immediately and call Triple Zero (000) for help if symptoms do not get any better or if they start to get worse.

If you:

Think you might have symptoms of asthma or hay fever, OR if you experience wheezing or coughing with your hay fever

  • See your doctor to get symptoms checked and get a proper diagnosis
  • Get an asthma or hay fever action plan
  • Make sure you have the right medication

Know you have asthma

  • Have regular reviews with your doctor to ensure that you have the right medication and good control of your asthma
  • Get an updated asthma action plan that includes advice for epidemic thunderstorm asthma
  • If you have been prescribed a preventer medication – take it every day, even if you feel well
  • Always carry your reliever medication with you – this is your emergency asthma first aid medication

Have had asthma in the past

  • Talk with your doctor about your risks of epidemic thunderstorm asthma and what additional actions would be appropriate for your individual situation, particularly the need for a preventer over the grass pollen season.

Know you have  hay fever

You should understand that you are at increased risk of having asthma, as well as asthma during an epidemic thunderstorm asthma event.

  • If you wheeze or cough with your hay fever, you may have asthma without knowing it. Around 1 in 4 people with hay fever also have asthma, and it is important to recognise that pollen can trigger asthma as well as hay fever symptoms. People with hay fever who also develop symptoms such as wheeze, shortness of breath and chest tightness should see their doctor.
  • See your doctor or pharmacist about a hay fever treatment plan and what you can do to help protect yourself from the risk of thunderstorm asthma, including having an asthma reliever puffer – which is available from a pharmacy without prescription.
  • If you develop asthma symptoms, follow the 4 steps of asthma first aid and make sure you follow up with your doctor. 

What should you do if you are experiencing asthma symptoms?

In an emergency, always call Triple Zero (000).

Follow your written asthma action plan or commence Asthma First Aid. If you are experiencing:

  • a severe or life-threatening asthma attack, call an ambulance - Dial Triple Zero (000) and then start asthma first aid. 
  • a mild to moderate asthma attack, start asthma first aid.

No matter where you are, a pharmacy or doctor’s surgery can assist you – don’t hesitate to seek help. Blue/grey reliever puffers are available over the counter from any pharmacy and they can assist with Asthma First Aid.

Click here for information on recognising signs of an asthma flare-up or attack and how to respond with Asthma First Aid. 

Download the Asthma First Aid Steps

DL (PDF 58.4KB)
A5 (PDF 58.6KB)
A4 (PDF 59.5KB)
A3 (PDF 60KB)

Download the Asthma First Aid App from the iTunes store or Google Play

Apple app store Google Play store

More information & resources

Thunderstorm Asthma Brochure (PDF 739.6KB)
Thunderstorm Asthma Poster (PDF 3.3MB)
Thunderstorm Asthma Campaign - Asthma First Aid Steps (PDF 96.9KB)
Asthma Australia's Thunderstorm Asthma - Consumer Survey Report 2016 (PDF 8.3MB)
Learn more about asthma and hay fever
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