Australia's health system is still unprepared for harm caused by bushfire smoke, despite lessons that should have been learned from the last mega-fire season.
A report by the Global Climate and Health Alliance released on Thursday warns the health threat will get worse unless governments support communities and health systems to step up.
Bushfire smoke is particularly harmful for unborn babies, children, the elderly and people with existing medical conditions.
Studies among firefighters have shown that lung function can return to normal but the cumulative impact of repeat exposure is unknown.
The report, The Limits of Livability, draws on case studies of bushfire harm to health in Australia, Canada and across Brazil's Amazon rainforest.
Australia's health protection advice is currently limited to advising on short-term exposure of a few hours or days.
But the 2019/20 bushfires created smoke conditions that lasted for months.
Canberra recorded the worst air quality in the world during the 2019/20 bushfire season, with people warned to stay indoors as the capital choked through an unprecedented shutdown.
"Not one of us was prepared for a bushfire smoke problem," cardiologist Dr Arnagretta Hunter said.
"It doesn't fit into the framework of our understanding of the environmental hazards in Australia.
"The next one could be worse."
Smoke from landscape fires causes an estimated 339,000 premature deaths per year worldwide, many more than the lives lost immediately in fire zones.
During Australia's 2019/20 bushfires, smoke caused 429 premature deaths, 3320 hospital admissions for cardiovascular or respiratory conditions, and 1523 emergency asthma presentations.
The smoke-related health costs over the bushfire season reached $1.95 billion, with the long-term impacts of exposure to bushfire smoke still unknown.
As communities begin to recover, the mental health impact can also be devastating.
Report lead author Frances MacGuire said health services in vulnerable countries must plan for longer and more intense fire and smoke events.
Heat and smoke-proofing new hospital buildings, and ensuring there are adequate supply flows of everything from masks to asthma inhalers is recommended.
Better public health information is also needed to provide practical advice on fire and smoke risk.
The report also backs Indigenous forest management techniques and integrating that knowledge into fire agencies.
"We want people to be fire practitioners, to start caring for the land and apply the right fire for the right country type," said Indigenous fire stick practitioner Noel Webster.
"But they don't do that, they got one fire methodology. And that applies right across the landscape."
On the international stage, Australia could make far greater progress on climate change than it has to date.
The report backs renewable energy and an end to taxpayer subsidies for new coal, gas and oil exploration to offer health benefits while supporting the push to limit global warming.
NSW South Coast public health doctor Joanne Walker said climate change clearly played a role in the conditions that led up to Australia's fires and the drought that preceded them.
"These are the kinds of health impacts that climate change has, and will continue to have, if we do not take urgent action to address the climate change crisis," Dr Walker said.
Australian Associated Press