The short version
- Spring hay fever with wheeze or cough is the single strongest risk factor
- Risk runs from October to December, on days with high grass pollen and a storm front
- Treating hay fever properly through the season lowers the risk
- Anyone at risk should have a reliever inhaler and a written action plan
What actually happens
On days with high grass pollen, a particular kind of storm front can sweep pollen grains up, rupture them in humid air, and scatter fragments small enough to reach deep into the lungs. Ordinary pollen is filtered by the nose. These fragments are not.
The result can be sudden, severe wheeze and breathlessness affecting a large number of people at once, within minutes to hours of the storm arriving. Victoria has the world's most significant recorded experience of this, and western Victoria's grasslands put Ballarat squarely in the zone.
Who is most at risk
- Anyone with spring hay fever, particularly if it comes with cough, wheeze or chest tightness — even without an asthma diagnosis
- People with asthma, especially where it is poorly controlled
- People sensitised to ryegrass pollen
- Anyone who has had breathing symptoms during a previous spring storm
The group most often caught out is the one that does not think of itself as asthmatic — people who put a spring cough down to hay fever and have never owned a reliever inhaler.
What to do before the season
Book a review in September or early October, before the season peaks. A useful appointment covers whether your hay fever is being treated adequately, whether you need a preventer for it, whether you should have a reliever inhaler and a spacer, and whether spirometry would clarify what is going on.
Treating hay fever properly is not a cosmetic concern here. Controlled nasal symptoms through the season measurably lowers the risk of a thunderstorm asthma event, and improves asthma control generally.
On a high-risk day
Victoria runs an epidemic thunderstorm asthma risk forecast through the grass pollen season. On high-risk days: stay indoors with windows closed while the storm passes, use air conditioning on recirculate if you have it, carry your reliever, and avoid being outside during the wind gusts that arrive ahead of the rain.
Asthma first aid, worth knowing by heart
Sit the person upright. Give 4 separate puffs of a blue reliever through a spacer, taking 4 breaths for each puff. Wait 4 minutes. If there is no improvement, repeat. If there is still no improvement, call 000 and say it is asthma, continuing the reliever while you wait.
Call 000 immediately if the person cannot speak in full sentences, if their lips look blue, or if they are drowsy. See asthma and COPD for how action plans work.
Common questions
Yes. Many people affected have spring hay fever and no asthma diagnosis. Hay fever with cough, wheeze or chest tightness is the key risk signal.
Grass pollen season, roughly October to December, on days combining high pollen with a particular kind of storm front. Victoria publishes a risk forecast through the season.
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