Victorians have warned to prepare for a possible thunderstorm asthma outbreak throughout the state.

Health authorities have warned of a moderate risk for “an epidemic thunderstorm asthma event” for the state’s North Central and North East districts on Monday.

A Department of Health and Human Services spokesman said moderate was in the “plan and prepare stage” of the early-warning system, and there was no immediate danger.

But people in affected areas should check the thunderstorm warning app or VicEmergency for updates in case the situation changes, and have their asthma plan ready.

A thunderstorm asthma warning system was introduced in Victoria following the deaths of nine people last year from what experts said was the world’s worst recorded asthma thunderstorm.

The traffic-light warning system was raised to moderate on Sunday for the North Central, Northern Country and Central districts, which includes Melbourne.

The warning comes after nine people died as a result of thunder storm asthma in Melbourne last November.

The findings of a review released in February found that few public health alerts were issued last years outbreak because emergency chiefs did not understand the cause of the crisis.

The rare phenomenon was triggered by a severe storm carrying pollen particles that crippled people with asthma attacks and breathing problems.

Victoria’s inspector-general for emergency management, Tony Pearce, concluded more lives could have been lost if the triple-0 service, paramedics and hospitals had not acted so swiftly.

“It was almost an exceptional response based on the fact that nobody really understood what they were responding to,” he said.

“It is tragic, nine people have passed away as a result of this, but were it not for the way in which the agencies worked together and the system responded on the night, I think that figure could have been a lot higher.”

The report found the rapid onset and scale of the emergency was unexpected and unprecedented.