Victorians with asthma and hayfever are being advised to carry their puffer at all times and move inside amid potentially deadly thunderstorm asthma conditions.
A high to moderate risk of epidemic thunderstorm asthma has been set down for western and central parts of Victoria on Wednesday as severe storms sweep across the state, bringing damaging winds and heavy rain.
Ten people died during or soon after a thunderstorm asthma event in Melbourne on November 21 in 2016, with about 1400 people also treated in hospital.
Thunderstorm asthma can be triggered when a high pollen count combines with heat and a storm that brings wind and moisture.
Chief Health Officer Brett Sutton has issued an air quality warning to residents in the Mallee, Northern Country, Wimmera and South West districts.
They've been told to be on the lookout for signs of asthma or breathing difficulties due to the combination of thunderstorm activity and high grass pollen levels.
"If you have a history of asthma or hayfever, or you experience wheezing, breathlessness, a feeling of tightness in the chest or a persistent cough, you should have reliever medication with you at all times today," the advice says.
"Avoid the wind gusts before the storm. Go inside and close your windows and doors before and during the storm."
"If you're experiencing any of the above symptoms you may be having an asthma attack."
Professor Sutton said there was an "increased chance" of people suffering an asthma attack or breathing difficulties.
If someone suffers an asthma attack or is struggling to breathe, triple-zero should be called immediately.
It comes as the Bureau of Meteorology updates Wednesday's warning for severe thunderstorms across most of the Mallee and Wimmera.
The wild weather is expected to reach central parts of Victoria including Melbourne during the early to mid-evening, senior forecaster Richard Russell says.
The thunderstorms and high pollen count has the potential to create hazardous conditions, with the bureau briefing the Department of Health and Human Services on the situation.
"We see thunderstorms a lot (in Victoria) during spring," Mr Russell said.
"It's our most common time to see them and we do get the occasional severe storms which we are expecting today.
"But the big factor in play here is the fact that the pollen is so high across the state."
Justin Dunlop, Ambulance Victoria's state health commander, said earlier this week the bureau had informed him the next fortnight would be the peak of this year's October to December pollen season.
