Global study: Wildfire smoke kills people in cities far from fires

Guatemala, Thailand, and Paraguay had the highest proportion of estimated annual deaths from wildfire smoke.

Wildfire smoke causes more than 33,000 deaths a year across 43 countries, according to a new global study.


While previous studies estimated premature deaths from wildfires in a specific country or region, authors of a study published Wednesday in Lancet Planetary Health say this is the most comprehensive assessment to-date of global wildfire mortality. The findings come as the smoke from yet another season of record-breaking wildfires in the Northern Hemisphere impacts air quality hundreds of miles away from burn areas.

"Policy makers and public health professionals should raise awareness of wildfire pollution to guide prompt public responses and take actions to reduce exposure," write the study authors.

The study authors first estimated daily fine particulate matter (PM 2.5) concentration using a combination of machine learning, ground measurements, weather conditions, and chemical transport models. They then cross-referenced those pollution levels with data on more than 65 million deaths from 2000-2016 across 749 cities in 43 countries to get city-specific death estimates from wildfires.

They found that short-term exposure to wildfire PM 2.5 pollution caused, on average, 33,150 deaths a year in the countries looked at in the study, with an estimated 6,993 cardiovascular deaths and 3,503 respiratory-related deaths a year.

Of the countries studied, Guatemala had the highest proportion of estimated deaths from wildfire smoke, followed by Thailand and Paraguay. The authors note that all the mortality data used in the study comes from cities, and that the study is not a comprehensive look at global mortality; for example, although wildfires have burned more than 40 million acres in Siberia this summer, no Russian cities were included in the study.

Far-reaching impacts of wildfires

Lake Tahoe wildfire

Wildfire approaching South Lake Tahoe, September 1, 2021. (Credit: The National Guard/flickr)

Lead author Yuming Guo, professor of global environmental health and biostatistics at Monash University, told EHN that he was surprised to see that citizens from certain countries that don't have frequent wildfires, like France and Germany, were still harmed from wildfire smoke.

PM 2.5 refers to particles that are 2.5 microns or smaller in diameter—for reference, a human hair is about 70 microns wide. Because of their small size, these fine particles can travel deep into the lungs, where they can damage airways and enter the bloodstream. Children, infants, older adults and people who already have heart and lung conditions are especially at-risk from PM 2.5 pollution.

While wildfires are far from the only source of PM 2.5 pollution in cities, the study authors found that PM 2.5 exposure from wildfires was more deadly, and longer-lasting, than fine particle pollution from other urban sources. They suspect that's in part because of the chemical makeup and smaller size of the particles in wildfire smoke.

Wildfire smoke also contributes to suicide, diabetes, renal diseases, and other conditions, said Guo. The study authors suggest that future research should look at the mortality data by age, sex, and other factors to better understand who is most vulnerable.

Climate change is worsening wildfires by making wildfire-prone parts of the world, like California and Australia, hotter and drier.

Banner photo credit: Chris LeBoutillier/Unsplash

Get our Good News newsletter

Get the best positive, solutions-oriented stories we've seen on the intersection of our health and environment, FREE every Tuesday in your inbox. Subscribe here today. Keep the change tomorrow.

Feeling anxious about climate change? Experts say you're not alone

Mathitha Ramachandran, a junior at Fox Chapel Area High School, is only 16 years old but she's already spent years worrying about climate change.

Keep reading... Show less

Invasive species are threatening Antarctica's fragile ecosystems

Keeping Antarctica pristine is becoming more challenging with growing threats from human activity and climate change.

They knew industrial pollution was ruining the neighborhood's air. If only regulators had listened

Raw throats, burning eyes, strong acid smells. Air monitoring that showed chemicals linked to leukemia. Barbara Weckesser and her neighbors told regulators that air pollution was making them sick. The law let them ignore her.

Don’t call it climate change. Red states prepare for ‘extreme weather’

Bracing for global warming is the rare climate issue that appeals to both Republicans and Democrats, and 34 states have done some sort of climate-adaptation planning.

How ‘climate migrants’ are roiling American politics

Refugees fleeing weather-related disasters are changing the political equation in Florida, Virginia, California, Idaho and beyond.
From our Newsroom

​​How to address the looming crisis of climate anxiety

As climate change worsens, the need will grow for mental health services. Some therapists are recommending climate action to ease worry. Others are advocating for community-based therapies to fill the gap.

Silent Earth: Averting the insect apocalypse

As insects become more scarce, our world will slowly grind to a halt, for it cannot function without them.

Worsening heat waves are hammering the disabled community

EHN talked to people with disabilities put in increased danger during last summer's Pacific Northwest heat waves. Activists say accessible cooling centers and air conditioning are key to combating this injustice.

Colonialism, the climate crisis, and the need to center Indigenous voices

As world leaders gather at COP26, the lack of acknowledgment for the historical root causes of the current climate crisis has hamstrung our ability to ensure equitable climate adaptation for marginalized communities.