Nearly three-quarters of the planet will be facing a significant increase in wildfires by 2100, leading to severe public health impacts, a new report by the Global Climate Health Alliance concludes.

“Bigger, more frequent forest and bush fires are having increased and not yet well-studied health impacts on people—including through longer and more frequent exposure to fire smoke by larger populations in distant cities,” the Alliance writes in a release.

The new report, titled “The Limits of Livability: The Emerging Threat of Smoke Impacts from Forest Fires and Climate Change,” outlines a familiar and dangerous feedback loop: more wildfires will mean more carbon lost into the atmosphere, leading to higher temperatures and yet more fires.

But long before that cycle becomes the norm, many more people will experience the public health impacts of breathing wildfire smoke—largely due to policy-makers’ failure to step up to the already-present demands of those impacts, the Alliance says.

“Smoke from landscape fires causes an estimated 339,000 premature deaths per year worldwide, many more deaths than those lost directly, yet receives relatively little attention,” the report explains. Wildfire smoke can travel vast distances (smoke from Australia’s 2019-2020 bushfire season travelled 66,000 kilometres), and it “contains a range of pollutants including particulate matter, carbon dioxide, nitrogen oxides, and volatile organic compounds.”

In British Columbia, the researchers found that “wildfire particulate matter may be more harmful to health than urban particulate air pollution,” with “impacts on respiratory and cardiovascular health…observable within one hour of exposure to PM2.5.” 

The report includes “snapshot” case studies of the wildfire situations in Canada, Brazil, and Australia, providing granular data on the “limits of livability” on a wildfire-plagued planet. It shows a clear correlation between increased levels of PM2.5 particulate matter and poor pulmonary health.

One study of Yellowknife’s 2014 wildfire season found that when PM2.5 increased by just 10 micrograms per cubic metre, “there was an associated increase in emergency room visits of 11% for asthma, 6% for pneumonia, and an 11% increase in chronic obstructive pulmonary disease (COPD)-related hospital admissions.” Those most at risk include children, seniors, anyone who spends a lot of time outdoors (workers and homeless people), and people with certain pre-existing health conditions. 

The report also cites studies linking wildfire smoke exposure to poor pregnancy outcomes, including low birth weights and the onset of gestational diabetes in mothers. The authors also express concern about “the mental health impacts from isolation, decreased physical activity, and reduced connection to the land, particularly for Indigenous people.” 

But despite the urgency, policy-makers have yet to take adequate action, the report states. “Government response to wildfires has largely centred on emergency response to the immediate impacts of the fires themselves, with limited preparation and response to address either short- or long-term impacts of wildfire smoke exposure.” 

Report co-author Frances MacGuire said this imbalance owes in part to “significant research gaps in understanding the full health impacts of smoke from increased wildfire risk in a warming world, and on primary and secondary health services.” For example, “current Canadian public health advice for wildfires is based on responding to episodes that last three days to a week.” 

That kind of advice proved woefully inadequate for the nearly three-month 2014 wildfire season in Yellowknife, for the 10-week state of emergency prompted by the 2017 wildfire in B.C., and for the 23-day state of emergency imposed by the same province the following year. 

One critical element of a public health-informed approach to wildfire smoke would be to “future-proof hospital design and buildings,” the Alliance says. During the Yellowknife fires, for example, “smoke entered the hospital operating theatre, which meant it could not be used for several days at a time.” 

The report also urged stronger public health messaging on wildfire pollution, the creation of “easy to use emergency plans for residents and communities,” and policy that addresses inequity in the impacts of smoke exposure, “including recognition of greater vulnerability of Indigenous people living in remote areas.” 

The most important policy measure, the report added, is “to mitigate climate change, to address this underlying and major contributor to wildfire extremes.” The report authors called on the Canadian government to end public subsidies for fossil fuels, and to “do its fair share and make greater progress on climate change than it has to date, aligning its climate mitigation commitments with the Paris Agreement target of well below 2°C and aiming for 1.5°C.”