In November 2016, emergency departments of Melbourne, Australia, were overwhelmed by a sudden surge of patients with asthma exacerbations. There was a 672% excess of breathing-related emergency presentations, with 992% more asthma-related admissions than normal. Many of these patients had never had asthma attacks before (72%), but most had a history of hay fever (95%).
The dramatic flood of patients put significant strain on hospital systems, highlighted by some hospitals running out of stocks of inhaled medicines for asthma exacerbations or rooms to treat patients in.
The cause of this bizarre epidemic – dubbed thunderstorm asthma – is still not clear, but it has been theorised to be related to pollens. It has been known for over 30 years that thunderstorms can pick up large volumes of pollen from one area, then dumped on an urban area far away. Because the pollen were exposed to high levels of moisture, they can burst into very small fragments that make it easier to be inhaled into the lungs, bypassing the natural filter systems in the nose.
There is also a possibility that these thunderstorms introduce pollen from species such as rye that are more allergenic than typical pollen found in residential areas, causing worse reactions.
The drastic increase in pollen density and increased penetration to the lungs can trigger a severe asthma attack, particularly in people whose immune systems are sensitive to pollen (hay fever). In the case of the 2016 Melbourne event, ten people ended up dying, while more than 500 excess people were admitted to hospital compared to the normal asthma admission rate.
Instances of thunderstorm asthma have been recorded throughout the world, but scientists have not been able to prove the exact cause. It is a staunch reminder that nature and the environment have direct impacts on our health, in ways we may not even be able to imagine.