Is thunderstorm asthma becoming more common?

With the arrival of spring comes warnings about thunderstorm asthma. But ten years ago, most of us hadn’t heard of it.

So where did thunderstorm asthma come from? Is this a recent phenomenon?

In 2016, the most in the world catastrophic storm asthma the event took Melbourne by surprise. Part of the response to this is to escalate warnings and monitoring.

However, there are also signs that climate change may be making storm asthma more likely, with more extreme weather conditions, longer pollen seasons and an escalate in the number of Australians reporting hay fever.

A groundbreaking disaster

Many Australians first heard about thunderstorm asthma in November 2016, when: important event shook Melbourne.

Estimated during an overnight storm 10,000 people were taken to hospitals due to severe asthma attacks. Faced with thousands of calls to emergency numbers, ambulances and emergency departments were unprepared to cope with the rapid escalate in the number of people requiring urgent medical care. Unfortunately, ten of these people died.

It was the most catastrophic event in the history of thunderstorm asthma and the first case of death anywhere in the world.

The Victorian Department of Health responded implemented initiativesincluding public awareness campaigns and improving health and emergency services to prepare for future storm asthma events.

Network pollen monitoring stations also established statewide to collect data to lend a hand predict future events.

A problem for several decades

Although this event was unexpected, it was not the first case of thunderstorm asthma in Australia – we have known about it for decades.

Melbourne reported its first case of thunderstorm asthma in 1984, just a year after the phenomenon occurred first discovered in Birmingham, UK.

Since then, cases of thunderstorm asthma have been reported in other parts of Australia, including Canberra and Novel South Wales. But it is still most common in Melbourne. Compared to any other city (or country), the difference is significant: over a quarter of all known events worldwide took place in Melbourne.

Why Melbourne?

Melbourne’s location makes it a popular location for these types of events. Winds blowing from the north of Melbourne are usually parched and balmy because they come from the deserts of central Australia, while winds from the south are cooler because they come from the ocean.

When balmy and cold air mix over Melbourne, it creates ideal conditions storms form.

Northern winds also bring vast amounts of pollen from agricultural fields to the city, especially grass pollen. It’s not only that the most common cause seasonal hay fever in Melbourne, but also a the main factor causing thunderstorm asthma.

Why grass pollen?

There is a particular reason why grass pollen is the main culprit of thunderstorm asthma in Australia. There is a lot of humidity in the air during storms. The grass pollen will absorb this moisture, causing it to swell like a water balloon.

If the pollen absorbs too much water in the air, it may crack or “rupture”, releasing hundreds of microscopic particles into the air that can be carried away by mighty winds.

Typically, when you inhale pollen, it gets stuck in your upper respiratory tract – such as your nose and throat. This is what causes typical hay fever symptoms such as sneezing or a runny nose.

But microscopic particles released from torn grass pollen do much smaller and don’t get stuck in the upper airway so easily. Instead, they can travel deep into the respiratory tract until they reach the lungs. This can cause more sedate symptoms, such as wheezing or difficulty breathing, even in people with no previous history of asthma.

Grass pollen burst.
Kira Hughes/included, CC BY

So who is at risk?

You might think that asthma is the biggest risk factor for thunderstorm asthma. In fact, the biggest risk factor is hay fever.

Until 99% of patients patients who went to the emergency department during the 2016 Melbourne event had hay fever, while the majority (60%) had not previously been diagnosed with asthma.

Every person hospitalized patients were allergic to at least one type of grass pollen. Everyone had a sensitivity to darnel.