Thunderstorm Asthma - Protect yourself this pollen season

21 December 2018

By Dr Angie Bone , Victoria’s Deputy Chief Health Officer

We are now in the midst of Victoria’s grass pollen season, which causes an increase in people experiencing asthma and hay fever each year. The season also brings the chance of thunderstorm asthma.

Here is a short video that explains what thunderstorm asthma is.

Thunderstorm Asthma Overview

What is thunderstorm asthma?

Thunderstorm asthma is asthma that is triggered by a unique combination of high amounts of grass pollen in the air and a certain type of thunderstorm.

Grass pollen grains get swept up into the air and carried for long distances. Some of the pollen grains burst open and release tiny particles that are concentrated in the wind gusts that come just before the thunderstorm. These particles are small enough to be breathed deep into the lungs, making it difficult for people to breathe.

For people who have asthma or hay fever, this can trigger asthma symptoms very quickly.

These symptoms  include wheezing, feeling short of breath and tight in the chest, and coughing. They can be sudden, serious and even life threatening.

While these events are uncommon, when they do occur, it is typically during the grass pollen season – between October and the end of December.

When this phenomenon causes a large number of people develop asthma symptoms over a short period of time, it is known as epidemic thunderstorm asthma.

Why am I hearing about thunderstorm asthma?

Allianz Global Assistance Overseas Health - Thunderstorm Asthma in Victoria

On 21 November 2016, Melbourne experienced the world’s largest epidemic thunderstorm asthma event , with thousands of people developing breathing difficulties in a very short period of time.

Calls to 000, Ambulance Victoria, and our hospitals were pushed to the limit with huge spikes in ambulance callouts and people presenting to hospital emergency departments. Tragically, the event contributed to 10 deaths.

Unfortunately, many people who were affected in November 2016 did not know about the risk to their health or the steps to take to protect themselves.

Who is at risk of thunderstorm asthma?

People with asthma and people with hay fever are at risk of thunderstorm asthma.

This includes people who have had asthma in the past, and people with undiagnosed asthma. It’s therefore important for people who experience asthma symptoms, such as wheezing or feeling tight in the chest, to talk to their doctor – even if these symptoms come and go.

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

Having both asthma and hay fever or poorly controlled asthma increases the risk further.

Allianz Global Assistance Overseas Health - Who is at risk of thunderstorm asthma?

We also know that people with cultural backgrounds from Asia, Southeast Asia, India and the Indian subcontinent were over-represented in hospital emergency department admissions in November 2016.

The reason for this is not fully understood, but we do know that it’s common for people who have moved to Australia from other parts of the world to develop asthma and hay fever after they move here. Research suggests that people who have moved to Australia from Asia are more likely to develop hay fever the longer they stay in Australia.

How can I prevent thunderstorm asthma?

If you think you may have asthma or hay fever, talk to your doctor and get an asthma action plan or hay fever treatment plan and the right medication. It’s better to check now and get these conditions under control.

Some medications can take time to become effective, so it’s important to start treatment as soon as possible. Ideally, you should talk to your doctor and update your plans each year before the start of the grass pollen season.

Good asthma management year-round, as well as treating hay fever symptoms, makes a person less vulnerable to asthma flare-ups. This includes taking preventer medication as prescribed, using correct inhaler technique, having an up-to-date asthma action plan and an annual review with your doctor.

During the grass pollen season (October–December) you can also check the epidemic thunderstorm asthma forecast, which is available on the VicEmergency website (and app) or the Melbourne Pollen website (and app).

With access to the forecast, people at increased risk can take actions to protect their health on moderate or high risk days, such as carrying reliever medication with you and avoiding being outside during any thunderstorms that emerge, especially the wind gusts that come before the storm.

Good asthma and hay fever control, together with avoiding exposure to springtime thunderstorms (especially the wind gusts that precede them) are the best ways to prevent thunderstorm asthma.

It's also important for everyone in the community to know the signs and symptoms of asthma, and know the four steps of asthma first aid so they know what to do if someone is having an asthma attack.

Managing asthma and allergies matters. For more information, visit the Better Health Channel at

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