More than a week after a rare condition known as thunderstorm asthma struck Australia's second-largest city the death toll has risen to eight with one other person on life support, officials said on Tuesday.

The latest two victims died in hospital intensive care units on Monday night and Tuesday morning from medical complications stemming from a wild thunderstorm that struck Melbourne on Nov. 21, a Health Department statement said.

Another patient remained in intensive care. Another six were in hospitals with less serious respiratory and related conditions.

Last week's storm caused rain-sodden ryegrass pollen grains to explode and disperse over the city, with tiny pollen particles penetrating deep into lungs. Around a third of patients who suffered asthma attacks reported never having asthma before.

The storm overwhelmed emergency services and hospitals in this city of 4.5 million people, with 8,500 receiving hospital treatment.

The world's first recorded thunderstorm asthma event occurred in Melbourne in 1987, when hospitals reported a five-fold increase in asthma cases. Similar events have happened in the United States, Canada, Britain and Italy. The last major event in Melbourne was in November 2010.