What is thunderstorm asthma?

By Stephanie Chalkley-Rhoden.

Melbourne is known as a global hotspot for thunderstorm asthma — a condition brought on when storms play havoc with pollen which can even affect people who do not normally suffer from respiratory problems.

One in 10 Australians have asthma, a long-term lung condition with no cure that can make it difficult to breathe.

In ‘regular’ asthma, something triggers the muscles around a person’s airways to squeeze tight, swell and create more mucus. Experts have not been able to pin down what these triggers are.

But occasionally there are incidents of thunderstorm asthma that are sparked but large storms, like a cool change in spring, that can cause significant breathing problems to people who do not have the condition.

In Melbourne, almost after a spring weather change caused a mass-flare up across the city.

Robin Auld from Asthma Victoria said it was caused by a change in the size of pollen particles.

“What we understand is the heavy rain causes the rye grass pollen to absorb moisture and they then burst and become much smaller,” he said.

“And those smaller particles can be dispersed very easily by wind over quite a distance.

“It’s those smaller particles that can then get in through the nose, into the small bronchial tubes in the lungs and that’s what causes the allergic reaction.

“In normal circumstances the rye grass pollen can be trapped in the nose because it’s a little bit larger. [The hairs] catches things before it goes in.”

Thunderstorm asthma in Melbourne, Wagga Wagga, London

Mr Auld said the condition was quite rare, and the first known incident of thunderstorm asthma occurred in 1987 in Melbourne. Endemics have also been reported in London.

After another major incident in Wagga Wagga, researchers began looking into it.

“[It] found 95 per cent of those that were affected by thunderstorm asthma had a history of hayfever, and 96 per cent of those people had tested positive to grass pollen allergies, particularly rye grass,” Mr Auld said.

“I was at the Alfred Hospital in November 2010 in a work group and all of a sudden all of the doctors left, and I think 90 people had presented at their emergency department as a result of thunderstorm asthma, that was the last time there was a major impact in Melbourne.”

Following that incident in 2010, Associate Professor Cenk Suphioglu from Deakin University told ABC’s Catalyst program that Melbourne was a particular hotspot for thunderstorm asthma.

“Because when these pollens are being released, [they] are picked up by northerly winds and all of the growth is in the northern parts of Victoria,” he said.

“The northerly winds pick them up and bring them into the metropolitan area where most of us are, and then you have the perfect model system for thunderstorm-induced asthma.”

This post originally appeared on ABC News.