The reason is not entirely clear, but Australians are much more likely to have asthma than people living in any other country. About 11% of Australians suffer from respiratory problems, compared to just 1% elsewhere.
In Melbourne and other parts of south-eastern Australia, as far north as Canberra, Newcastle and Tamworth, people with asthma and / or hay fever (around 20% of the population) should be on alert throughout the spring for what is called an epidemic storm. asthma (AT). The dangerous phenomenon can lead to hospitalization and even death. Oddly, however, this has never been seen in Sydney.
“Unfortunately, a lot of people often underestimate and contract out both conditions,” says Marg Gordon, registered nurse and asthma and respiratory educator at National Asthma Council Australia. “Especially asthmatics, who can feel perfectly well between attacks and thus reduce or stop their preventive treatment. “
The first recorded incidence of AT in Melbourne was in November 1984. There have been eight major events since then, all of which occurred in November, with the exception of today’s storm.
This represents up to a third of the total known epidemics worldwide, making Melbourne the unfortunate world leader in TA. There have been at least 24 outbreaks of AT worldwide, in just six countries: Australia, England, Saudi Arabia, Iran, Canada and Italy.
Of all, the November 2016 outbreak in Melbourne is considered the deadliest, after 3,400 people sought emergency medical care and 10 died. In contrast, the second and third most serious epidemics sent 2,000 and 640 people to the emergency room. So not only do Melburnians suffer from AT more often than anyone else, but it is also more serious here, due to a combination of specific weather conditions and local flora.
The pollen comes from various trees, weeds and grasses (olive pollen triggered TA events in Italy) but in Melbourne the vast areas of ryegrass grown for grazing in the districts of Victoria Western and Mallee are the big deal. These grasses ripen in November, a time when Victoria is prone to wet spring storms.
“[Thunderstorm asthma] is caused by a combination of a high pollen day and a thunderstorm with strong winds and humidity, ”says Gordon.
“In Melbourne, most of our time comes from the west. Storm winds carry the pollen into the atmosphere, where they are saturated with moisture from the storm, shattering them into tiny particles.
“The winds that precede the storm (called outflows) then bring these tiny particles of pollen back to ground level, where they can be inhaled by people and directly enter their airways. If that person has asthma or allergies (even if they go undiagnosed), they may develop symptoms.
By comparing pollen counts, humidity and wind direction to conditions observed in previous events, the Bureau of Meteorology is able to predict TA events with reasonable certainty.
Anyone at risk is advised to avoid being outdoors during thunderstorms, to close doors and windows, and to put air conditioners into recirculation mode, if used. You should also have medication on hand and be prepared with an asthma action plan.
See here for more information on stormy asthma, including symptoms.