Experts giving evidence to the royal commission into the 'Black Summer' bushfires say far more people were impacted by the lingering smoke haze than the actual fires.
Smoke from Australia's recent summer of bushfires killed 455 people and impacted 80 per cent of the country's population, a royal commission into the disaster has heard.
The 'Black Summer' bushfires killed 33 people, destroyed about 3,100 homes and burned about 12 million hectares across Australia.
But experts giving evidence to the Royal Commission into National Natural Disaster Arrangements on Tuesday said smoke from the blazes affected far more people than the actual fires.
"Our estimate was 80 per cent of the population of Australia were adversely affected by smoke from these fires," Fay Johnston, from the University of Tasmania's Menzies Institute for Medical Research, told the inquiry.
In addition to the 445 "excess deaths" attributable to smoke from the bushfires, researchers said there had been 3,340 admissions to hospital for heart and lung-related problems and 1,373 additional presentations to emergency departments for asthma.
Researchers estimated the smoke-related health costs associated with premature deaths and hospital admissions were $2 billion.
"That was a major departure from anything we had seen in the previous 20 years," Associate Prof Johnston said.
The inquiry also heard it would take at least five years for people to recover from the trauma of the bushfires.
Research from Victoria's 2009 Black Saturday bushfires shows someone who has experienced a major disaster is at greater risk of mental health problems in the years afterward, University of Melbourne public health professor Lisa Gibbs said.
"When we're thinking about the recent season of bushfires, it's still very early days in the recovery," Professor Gibbs said.
"One of the recommendations from our research is that we always think in at least a five-year recovery framework from a major disaster.
"That's the reality of the process it takes."
About 200 of the 1,700 submissions received by the royal commission have focused on health and mental wellbeing.
Senior counsel assisting the commission, Dominique Hogan-Doran SC, said those submissions emphasised the compounding effect of the drought, bushfires and now the coronavirus pandemic.
The submissions highlighted the major stresses of incorrect, outdated and unclear information being provided during the bushfire emergency and the loss of internet and communications.
Ms Hogan-Doran said additional trauma had also been reported of people struggling to access medical services.
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Additional reporting by Claudia Farhart, AAP.