Thunderstorm asthma has returned to Melbourne sending hundreds of patients to hospital with asthma-related symptoms in less than 24 hours last week.

EDs across Victoria reported a spike in presentations following stormy conditions on Melbourne Cup Day, with 231 patients attending hospitals between 4pm on Tuesday 7 November and 2:30pm on Wednesday 8 November — more than five times the normal amount.

A thunderstorm asthma alert was issued for most of the state.

“We are seeing an increase in people suffering asthma symptoms across parts of Victoria,” stated a VicEmergency warning last week.

“People may experience asthma symptoms or difficulty breathing due to the combination of thunderstorm activity and high grass pollen levels.”

Victoria’s Department of Health developed a warning system after Melbourne experienced the world’s worst thunderstorm asthma event in November 2016, which killed 10 people and forced 14,000 people to seek urgent medicare care.

Thunderstorm asthma monitoring runs across Victoria from October to December during the peak grass pollen season.

There have already been multiple warnings issued this season.