Three people continue to fight for life after Melbourne 'thunderstorm asthma' outbreak

Three people remain in a critical condition one week after Melbourne's "thunderstorm asthma" emergency, which killed six people.

Twelve people continue to be treated in hospital as a result of the unprecedented health crisis last Monday.

“Five patients remain in intensive care, three in a critical condition, following this tragic, unforeseen event,” a spokesman for the Department of Health said in a statement today.

Yesterday the sixth death relating to the storm conditions was confirmed.  

More than 8500 patients were treated for breathing difficulties across Monday and Tuesday last week.

READ MORE: Woman who died in Melbourne storm remembered by family

The storm event saw a high pollen count and thunderstorm conditions combine to produce tiny particles in the air that penetrated deep into people's airways, causing attacks for asthma sufferers.

The Inspector-General for Emergency Management has announced an investigation into the cause of the deaths.

His findings will form part of an overarching review that will examine how Ambulance Victoria and emergency services responded and how the community was notified of the unfolding crisis.