Although benign, pollen from certain plants can trigger allergic diseases in sensitised individuals. Whole pollen grains landing in the eyes or nasal passages can trigger rhinitis or hay fever, characterised by a blocked or runny nose, sneezing and itchy eyes. According to a recent survey, around 30% of Australians will experience the symptoms of hay fever at some stage of their life.
Fragments of allergic pollen are small enough to enter the lower respiratory tract can trigger asthma in a sensitized person, causing their airways to narrow and making it harder for them to breathe. Around 1 in 10 Australians has asthma.