Approximately 2.4 million or 1 in 10 Australians have asthma, making this one of the most common medical conditions in Australia.
A large proportion of asthma is related to allergies to airborne particles, such as pollens, dust mites and animal dander. Many people will have heard of thunderstorm asthma due to media coverage of the recent severe thunderstorm asthma attack in which a number of people died and thousands needed acute medical care.
Thunderstorm asthma has been reported in a number of countries around the world, however Australia has had more than its fair share, with at least 6 episodes in the last 30 to 40 years. Thunderstorm asthma in Australia is mostly related to grass pollen allergy, and usually occurs in Spring, often towards the end of Spring when pollen counts are highest.
Many of the people affected by thunderstorm asthma were not previously aware they had asthma, however most seem to have a background of seasonal allergic rhinitis (hayfever). Hayfever occurs when people are allergic to tiny grass pollen particles in the air and they inhale these into their nasal passages triggering off an allergic reaction which results in sneezing, itchy eyes, runny nose and a dry irritating cough. Although the pollen particles are tiny they are still large enough to be trapped in the nose and not get any further into the body. In thunderstorm asthma the grass pollen particles are broken into tiny particles which are then inhaled right down into the lungs triggering off a severe allergic reaction and airway narrowing.
Thunderstorm asthma doesn’t just happen with every thunderstorm as it requires a number of things to coincide to create a “perfect storm”. Firstly there needs to be a very high pollen count, then the wind needs to blow in the right (or perhaps we should say wrong) direction, blowing the pollen particles towards the storm and up into the clouds where the pollen particles absorb water until they burst releasing huge amounts of miniscule particles into the air, the weather then needs to blow the particles back down to the ground, where people can inhale them through their noses and into their lungs.
The people most affected by thunderstorm asthma appear to be the people not taking any asthma medication. Ventolin (salbutamol) is an asthma reliever medication that helps relieve muscle spasm in inflamed airways, however is not effective as the only treatment in thunderstorm asthma as it doesn’t treat the underlying cause of inflammation. Asthma preventer medication (inhaled corticosteroids) is a very effective and safe form of treatment which helps treat the airway inflammation that occurs when you inhale particles you are allergic to down into your lungs.
As you can see a thunderstorm asthma attack won’t happen every time there is a thunderstorm, but in the right setting may cause havoc. If you suffer from seasonal allergic rhinitis (hayfever) or have any symptoms of asthma such as wheeze, breathlessness, night-time cough, the next time you see your GP it would be best to discuss whether you need any further assessment or strategies to minimise your chance of a thunderstorm asthma attack.
Dr. Chris Daley
Sleep and Respiratory Physician