What Is Thunderstorm Asthma, And Why Is It Worst In Melbourne?

Image: Getty/Mark Kolbe

Hospitals across Melbourne were put on emergency alert on Monday night as thousands of people called ambulance services, reporting breathing difficulties and other severe symptoms. Emergency rooms were so strained that day units were opened to handle the overflow. It was a severe outbreak of the phenomenon called "thunderstorm asthma" -- but how does an emergency like this actually happen?

Monday's outbreak was one of the worst in the short history in which the phenomenon has been known -- it was first named in Melbourne in 1987 after two epidemics in November 1987 and November 1989. In both instances, hospital visits were noted to increased between five and ten times within a single 24-hour period. This week's outbreak looks to be the first recorded instance of fatal cases of thunderstorm asthma, with three patients reported dead and others still in intensive care.

What Causes Thunderstorm Asthma?

Thunderstorm asthma mostly affects young people with a history of hay fever or allergic rhinitis, a condition which approximately 15 per cent of Australians have. Those who suffer from thunderstorm asthma don't necessarily have to have a prior history of asthma, however. Other victims of thunderstorm asthma tend to be people who have been diagnosed with forms of asthma so mild that it wasn't worth medicating.

The phenomenon occurs when a very specific set of circumstances combines to create a dangerous environment for those with pollen allergies. Where usually grass pollen is too large to enter the lungs, and ends up being filtered out by the lungs, moisture in the air on stormy days can cause the pollen to 'explode' into much smaller particles, which can make their way into the lungs. These tiny allergenic particles can cause an acute asthmatic attack in people with hay fever, even those who haven't experienced an asthma attack before. The symptoms often occur quickly, including breathing difficulty, coughing and in some extreme cases, even vomiting.

Why Is It So Bad In Melbourne?

Thunderstorm asthma has been described as an exceedingly rare event, but it seems that Melbourne is a prime candidate for outbreaks. Major occurences have happened in Melbourne both in the 80s and as recently as 2010, almost always happening in November. Other instances have been documented in Wagga Wagga, London, Birmingham and Naples.

Right now Melbourne is in the middle of its 'pollen season', with a large volume of rye grass pollen being blown in from the areas north and west of Melbourne. Even on a regular day, Melbourne's pollen season can be tough for those with hay fever. Add in the city's temperamental weather, and Melbourne's predisposition towards thunderstorm asthma starts to make a lot of sense.

"Melbourne, being surrounded by parks and bushland, combined with the well-recognised Melbourne 'four seasons in one day' weather patterns is particularly set up for this scenario," Dr Simon Judkins told The Age. "The movement from a hot a windy day where there is an increased pollen load in the air to an incoming storm front which adds a lot of moisture to the air will see pollens absorb the moisture, and burst. This releases thousands of tiny allergen particles which are then inhaled by people and can trigger asthma attacks."

Figuring out when an outbreak is going to happen is not so simple, however. It doesn't occur on all days when thunderstorms and a high pollen count combine, so there must be another as yet unknown factor to it. Figuring out this pattern is a little more difficult, as instances are so rare that it's exceedingly hard to study.

What Do You Do If You Have It?

So if you think you're being affected by thunderstorm asthma, what can you do? Those who have medication for pre-diagnosed asthma, can implement their asthma plan, but for others it may be an entirely new experience. If you ever have trouble breathing, call an ambulance right away.

With thunderstorm asthma, however, prevention is the best medicine -- especially when emergency services are likely to be tied up with thousands of other calls. During Monday's epidemic Victoria ran out of ambulances for a full hour, and even mobilised other emergency services to help. If you think you're likely to be at risk, you should be using a preventer inhaler -- a type of asthma medication that will reduce inflammation in the lungs over a longer period of time and reduce the likelihood of an asthma attack occurring at all.


Comments

    "If you think you're likely to be at risk, you should be using a preventer inhaler"

    Which means seeing your GP, as these are only available by prescription.

    However, for those with either very mild or only occasional wheezing episodes, another option would be to obtain a short-acting relief inhaler (salbutamol). This would at least allow some degree of self-medication in the event of such asthma attacks as described above, while waiting for an ambulance. Best of all, they don't require a prescription and can be ordered over the counter after a quick consultation with a pharmacist.

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