Another two people have died in the wake of last week's "thunderstorm asthma" outbreak, bringing the death toll for the freak weather event to eight.

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.