The unusual phenomenon of thunderstorm asthma

Did you know that people with asthma might be at risk of developing symptoms during stormy weather? “Thunderstorm asthma” is uncommon, but can cause severe asthma and breathing difficulties when pollen in the air and storm weather conditions combine. It can also affect people with hay fever or undiagnosed asthma.

Storm clouds and lightening over green field with text overlay "the unusual phenomenon of thunderstorm asthma"

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What is thunderstorm asthma?

Thunderstorm asthma describes asthma symptoms that can happen suddenly during spring or summer when there is a high pollen count combined with hot, humid and stormy weather. When pollen in the air comes into contact with water during storms, it can burst into tiny particles. Lightening can also burst pollen. Once released into the air, the smaller pollen particles are easy to inhale through the nose and mouth. Unlike normal pollen, these smaller particles can travel deep into the lungs and trigger serious asthma symptoms in people with asthma and/or pollen allergies.

Only certain weather conditions create a risk of this type of asthma.

Which countries have reported thunderstorm asthma events?

Thunderstorm asthma can occur in any part of the world where there is a combination of large amounts of grass pollen in the air and summer storms. Most reports of endemic thunderstorm asthma are from South Eastern Australia.

In November 2016 a major thunderstorm asthma event occurred in Melbourne, Australia. Thousands of people experienced sudden onset asthma and breathing problems at once. This made it difficult for ambulances and hospital emergency departments to provide urgent medical assistance to everyone who required it. Sadly a number of people passed away from as a result of severe asthma exacerbations.

After what occurred in 2016, thunderstorm asthma has become much more widely discussed in Australia. Asthma Australia now issues public alerts on high risk days.

Thunderstorm asthma is not a uniquely Australian issue. While it is most common in Australia, it has also occurred in the United Kingdom, the United States and Europe (Italy). According to medical journal, The Lancet, there were approximately 12 endemic thunderstorm asthma events in the 35 years to 2018.1

What are the symptoms of thunderstorm asthma?

People with hay fever may notice that their usual symptoms (like sneezing, runny nose, itchy and watering eyes) are worse on windy, stormy days.

Common symptoms of asthma include:

  • Shortness of breath
  • Wheezing
  • Feeling tight in the chest
  • Persistent coughing

Different people experience different asthma symptoms. Asthma in our family presents mostly as a persistent cough.

If you do experience symptoms, follow you asthma action plan or asthma fist aid. If your symptoms are not improving (or if you do not usually have asthma and do not have an action plan or asthma reliver medication) you should seek immediate medical help.

Heavy rain falling on rainbow striped umbrella with text overlay "Thunderstorm asthma and pollen allergies"

Who is at risk?

People with both asthma and seasonal hay fever are most likely to develop symptoms during thunderstorm asthma events. However, people with just hay fever and no history of asthma may also be at risk. This is particularly the case if you are allergic to rye grass, which is a common cause of spring hay fever in Australia. Thunderstorm asthma can also affect people who have previously undiagnosed asthma (and take them by surprise).

My doctor advised me that I am at risk of thunderstorm asthma. I don’t actually have regular asthma symptoms. However I do suffer from severe hay fever and am highly allergic to a number of different grass pollens, including rye grass. The only time I have developed significant asthma-like symptoms was after one of my increased doses of allergen immunotherapy (allergy shots) for my grass pollen allergies. As a result of this, I do actually carry a a compact asthma spacer and reliever medication in my bag in case of another reaction to my allergy shots. But I also make sure I carry my spacer and reliever medication with me on stormy spring days. (You can read more about the benefits of using a spacer device with your inhaler in our post – Asthma spacers 101: Do you need one?)

How to manage the risk

The National Asthma Council Australia advises that at risk people with hay fever and/or asthma should:

  • make sure hay fever symptoms are controlled and continue to take recommended medications (including nasal spray) as prescribed for the whole of Spring and early Summer (from September to the end of December here in Australia);
  • continue to take asthma preventer medications as prescribed;
  • always carry a reliever inhaler;
  • stay up to date with pollen counts and weather forecasts so that you know if thunderstorms are likely;
  • in the event of a storm, stay inside with windows and doors closed or make sure you switch your car air-conditioning to recirculating air 2.

Anyone with diagnosed asthma should have a written asthma plan to follow.

Also make sure that you learn asthma first aid.

Asthma Australia issues thunderstorm asthma warnings on high risk days. You can follow Asthma Australia on social media to get these alerts.

References and more information

For more general information about thunderstorm asthma, we recommend reading the following helpful articles and resources from peak allergy and asthma bodies in Australia, the United States and the UK:

If you need advice or information about your own asthma, allergies and personal risk of experiencing thunderstorm asthma symptoms, you should speak to your doctor or an allergist/immunologist.

*Disclaimer: Allergy Spot does not provide medical advice. You should always consult a suitably qualified medical practitioner in respect of your own medical conditions, symptoms or concerns. See our Website Terms for more details.

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