The smoke from the Marshall Fire carries pollutants across communities on Dec. 30, 2021, in Boulder, Colorado. (Photograph by RJ Sangosti/MediaNews Group/The Denver Post via Getty Images)

A Blazing Air Pollution Crisis

words by yessenia funes

A historic winter wildfire in Colorado challenges the notion of a wildfire season. The Frontline explores what that means for human health after a new study finds wildfires are increasing air pollution across the American West. 

At the end of December, Colorado saw its most destructive wildfire yet. The state is used to wildfires—but not in the winter. After all, Colorado winters are historically known for their snow. Unfortunately, climate change is altering the realities many communities have come to know. For the West, that means more wildfires—and more air pollution, too. 


The Marshall Fire’s cause remains under investigation, but hurricane-force winds and unusually dry conditions for the season fueled the flames, making it impossible to stop once they gained enough force. Snow that followed the destruction is what ultimately put the fire to rest. Before then, the Marshall Fire managed to kill at least one person and took down over 1,000 homes. The incineration of homes and inorganic materials, however, is especially harmful to human health when you consider the amount of toxins such substances release when burned. There’s also the ongoing COVID-19 pandemic, which makes people even more vulnerable to the impacts of this smoke.


A new study published last week looks at how air pollution is worsening across the West due to wildfires. While it doesn’t specifically assess the sort of pollutants that burning homes release, it did look at particulate matter and ozone, a dangerous combination that’s becoming more likely under prolonged wildfire seasons and warmer temperatures.


Welcome to The Frontline, where we take air pollution seriously. I’m Yessenia Funes, climate director of Atmos. Across the globe, more than 4 million people die a year from air pollution. In the U.S., where wildfire seasons are becoming a thing of the past as wildfires increasingly happen year-round, more people will suffer due to poor air quality. New research is giving us an idea of how many more. On Friday, President Joe Biden visited Colorado to see the devastation from the Marshall Fire firsthand. His constituents there need more than inspiring words; they need concrete climate action.






Hyapatia Lee has been living with asthma and chronic obstructive pulmonary disease (also known as COPD) since 1994. The Colorado resident is immunocompromised, so she’s had her fair share of pneumonia scares over her lifetime. That has scarred her lungs. 


However, these chronic diseases have been affecting her daily life more dramatically in recent years due to Colorado’s worsening wildfires. This has become even more frightening due to COVID-19, which has been found to be potentially more deadly for people exposed to wildfire smoke. Some days, Lee awakes struggling to breathe inside her own home. No, her windows aren’t open. And yet the pollutants that these wildfires release make their way inside, attacking her respiratory system. 


“I thought, What have I done? Did I forget to take one of my inhalers at the right time?” Lee said. “Then, I’ll start researching what’s going on in the environment and find out that there is a wildfire somewhere. One of those mornings, I found out the wildfires were all the way in California.”


Unfortunately, Lee is one of 46 million people across the West who experienced exposure to severe air pollution in 2020 when the smoke from California fires moved across the region. A study published last week in Science Advances found that simultaneous exposure to two air pollutants—particulate matter and ozone—has become more common over the last two decades as summertime wildfires have worsened across the West.


The authors gathered air pollution data between 2001 and 2020 for states including California, Oregon, Washington, Nevada, and Colorado. They looked for days that saw high levels of both pollutants and then assessed weather data to determine what conditions encourage the co-occurrence of both. The team identified a trend between hot, dry conditions and these pollution events. Finally, they added wildfire data to the mix to find links between the amount of land burned and the levels of air pollution.

“This is only going to get worse as climate change progresses.”

Hyapatia Lee

You see, wildfires release particulate matter when they burn material (whether that’s grasses or houses). That’s what makes up much of the smoke. Particles even finer than a strand of human hair can make their way through a person’s cardiovascular and respiratory systems when inhaled. Ozone, on the other hand, is a gas that forms when sunlight interacts with other chemicals, such as what’s released from vehicle exhausts or, in this case, wildfires. The hotter it is, the worse the ozone can be, which is why summertime wildfires are especially dangerous. 


Exposure to even one of these pollutants can afflict a person’s lungs, heart, or brain, but the science isn’t totally clear on what happens to the human body when exposed to both pollutants at the same time—especially if that exposure is long-term. The research that exists suggests that exposure to multiple air pollutants at once may cause lower birth weight among newborns. We know individuals living with chronic disease (like Lee) are more vulnerable to these health impacts. We also know that these individuals are disproportionately Black, Indigenous, or other people of color, but there’s growing concern over how even a healthy general population may be affected if people are regularly exposed to such high levels of pollutants. 


“People will still do all these things outside even though they’re breathing the equivalent of 20 cigarettes on a really bad wildfire smoke day,” said Dmitri Kalashnikov, a doctoral student at the Washington State University Vancouver and lead author of the paper, which is the first to assess the co-occurrence of these two pollutants across the entire western U.S. “We need more awareness of just how bad wildfire smoke and the associated air pollution is.”


This reality isn’t lost on Lee, who must take more medication whenever the wildfire smoke exacerbates her asthma or COPD. Some days, she can’t go outside at all. She’ll have to skip a planned grocery store run or pharmacy visit. She worries most about the world we’re leaving behind for her grandchildren and their children. “This is only going to get worse as climate change progresses,” Lee said.


While ozone wasn’t a problem during the recent Marshall Fire because it happened during winter when skies are more overcast, the fact it happened at all is a warning for how winters as we know them may evolve under the climate crisis. Still, the air pollution the fire created shouldn’t be ignored, especially the exposure firefighters experience, said Anthony Gerber, a Colorado-based pulmonologist and professor of medicine at National Jewish Health who is also the chair for the state’s Air Quality Control Commission. Plus, there remains the threat of toxic chemicals dispersed through the smoke that may be lodged inside homes that survived the fire. 


“That incineration of homes and cars and plastics and metals creates a really toxic mix of particulates that falls outside what we typically study or use for public health studies,” Gerber said, speaking for himself and not the groups for which he works. “We know, for example, from even more extreme events like when the World Trade Center was attacked and we had that tremendous amount of pulverized material, [that] a few days of exposure to that mix of dust, and [first responders] wound up with lifelong health problems.” 


Berger has seen firsthand what these wildfires are doing to our most vulnerable. A quarter of his work directly involves caring for patients, most of whom have lung disease. He sees how they struggle to get through summer months. Some of his patients benefit from walking outdoors, but that isn’t always possible during wildfires. “The scope and reach of the problem is big, and it’s growing,” Gerber said. 


Leaders can take steps to better manage forests and prevent fires, but they can’t be stopped in their entirety. We can’t regulate them away as we would other sources of air pollution, such as power plants or trucks. What our policymakers can do is heed the warnings of a heating planet to keep a bad situation from growing worse. They can end the production and consumption of fossil fuels and take tangible steps to reduce greenhouse gas emissions.


Otherwise, the fires and smoke will not only continue; they’ll grow more dangerous and deadly. The deaths and disease that follow will be on those elected officials who failed to act. They’ll have to reckon with the nightmare they’ve created. A nightmare of endless night as smoke muddles our skies. Leaders will have to confront their failure and what they’ve doomed us to become: a nation of people gasping for a breath of fresh air. 

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