Grass pollen season has begun in Victoria, with the state's chief health officer warning there is an increased risk of a thunderstorm asthma event.
The state's thunderstorm asthma risk forecasting system was turned on on Monday, with the system to run through to the end of December.
"We want everyone to be as prepared as they can for the grass pollen season," chief health officer Dr Brett Sutton said.
Thunderstorm asthma is thought to be triggered by a unique combination of high amounts of grass pollen in the air and a certain type of thunderstorm. For people who have asthma or hay fever this can trigger severe asthma symptoms.
The largest incident of thunderstorm asthma was in Victoria in November 2016, when thousands of people developed breathing difficulties in a very short period of time. Nine people died and almost 13,000 people presented to Victorian public hospitals.
Dr Sutton said people with asthma or hay fever are at risk of thunderstorm asthma, including those with undiagnosed asthma.
"It can result in symptoms such as wheezing, shortness of breath, feeling tight in the chest, or experiencing persistent coughing," he said. "It can be sudden, serious and even life-threatening."
"Even if you don't think you have asthma, don't ignore symptoms."
Dr Sutton said following the forecasting system can assist people to protect themselves, but shouldn't replace good asthma and hay fever care.
"Those at risk should always follow their asthma or hay fever treatment plan," he said. "Where possible, people with asthma and hay fever should also avoid exposure to springtime thunderstorms."
Epidemic thunderstorm asthma risk forecasts are available on the VicEmergency app and here.
Pollen observations and forecasts in Bendigo are available at melbournepollen.com.au and via the Melbourne Pollen Count App.