Roxburgh Park man Ranjith Peiris died in the intensive care unit at Northern Hospital on Tuesday morning.

Another person critically injured after last week's thunderstorm crisis has died since yesterday afternoon.

One patient continues to receive specialist ICU care in a Melbourne hospital and remains in a critical condition. Another seven people are still in hospital being treated for sickness related to the unprecedented outbreak.

Mr Peiris, 57, was put on life support eight days ago after he struggled to breathe and lost consciousness during the storm.

His son, Roshan, desperately tried to revive his father while the family waited more than an hour for an ambulance.

"He couldn't take a breath in so I was breathing air into him as forcefully as I could, started compressions," he told The Age on Saturday.

"He'd come back but then he'd go unresponsive, back to being unconscious, blue."

Roshan said his father passed away while receiving the last rites just before 12pm.

He said his distraught mother keeps reliving the events of Monday night.

"Mum just keeps saying, 'if only they told me, if only they told me. If only I knew I would have brought you here earlier'."

"If we knew how long the ambulance was going to take we could have done something. We could have taken him [to hospital] ourselves," Roshan said.

The Peiris family were last week critical of authorities' failure to warn about the impact of the storm and over the delayed emergency response.

They said had they know about the ambulance delays, they would have driven Ranjith to hospital themselves.

"How will the state react if there was a real disaster?", Roshan said.

Fairfax Media has revealed most Melbourne hospitals did not follow the state's health emergency plan during the unprecedented weather event last Monday, despite Health Minister Jill Hennessy likening its impact to 150 bombs going off across Melbourne.

The state's health authorities are also under pressure to explain why the public were not given information about the unfolding disaster on the night to alert people at risk and provide more advice about emergency care.

The outbreak triggered more than 1900 calls to Ambulance Victoria on Monday night and Tuesday morning, and hospitals across the city were inundated with 8500 patients suffering from respiratory conditions.

Dr Michael Sutherland, a Respiratory Physician and Allergist at the Epworth Hospital, said the event, which affected people without a history of asthma, was likely to be the most severe epidemic on record. He said the government was now working toward a co-ordinated warning system to be in place by next pollen season.

Asthma Australia is now surveying people who felt symptoms during last week's outbreak to better understand what can be done to protect them in future.

"Although these events are rare we need to think about how we can be best prepared in future," CEO of Asthma Australia Michele Goldman said.

The survey can be accessed here