Those at increased risk of thunderstorm asthma include:

• people with asthma
• people with undiagnosed asthma i.e. people who have asthma symptoms (such as wheezing, breathlessness, a feeling of tightness in the chest or a persistent cough) but have not yet been diagnosed with asthma
• those who have had asthma in the past
• people with hay fever (seasonal allergic rhinitis) who may or may not have asthma.

People with hay fever in south east Australia are likely to be allergic to grass pollen, and are therefore at increased risk of epidemic thunderstorm asthma. Having both asthma and hay fever or poor control of asthma increases the risk further.