When the Perins Peak Fire ignited west of Durango on May 24, a thick cloud of brown smoke darkened the sun.
As Durangoans breathed in, they ingested the toxic smoke.
Research has shown that wildfires have significant health consequences leading to cancer, respiratory disease and even premature death. Public health officials and medical groups say that as climate change worsens wildfires, the risks to human health in Southwest Colorado will only grow.
But even as they voice concerns about the health impacts of wildfires, a new report from the American Lung Association suggests a solution might already be in place.
“We know that climate change is making conditions more likely that we’re going to have more severe and frequent wildfires,” said Nick Torres, director of advocacy for the American Lung Association’s Colorado office. “If we do nothing, that is not going to benefit public health when it comes to the health impacts of wildfire smoke. We are recognizing that prescribed burning could be a useful tool to help address this increasingly urgent issue as we see more and more wildfires.”
As wildfires burn forests, they produce three significant sources of air pollution.
The first is coarse particulate matter, otherwise known as PM10. At 10 micrometers or smaller, PM10 is approximately one-fifth the width of a human hair.
Coarse particulate matter from wildfires exacerbates respiratory disease and often leads to irritation in the nose, throat and lungs, and can trigger sensitive groups like asthma and those with COPD, said Dr. Afif El-Hasan, a pediatrician in California and a former board member on the American Lung Association of California’s state governing board.
Ozone, while often associated with industrial pollution, is also a byproduct of wildfires.
“Ozone causes what seems to be like a sunburn on the inside of the lungs. It’s very irritating and causes an inflammatory response,” El-Hasan said.
But the most dangerous air pollutant wildfires produce is fine particulate matter, or PM2.5.
The health risk that PM2.5 poses is a direct result of its size; at 2.5 micrometers or less, PM2.5 is approximately 1/25 the width of a human hair.
“Because they are smaller, you can inhale them farther into your lungs,” said Brian Devine, environmental health director at San Juan Basin Public Health. “They do present the greatest health problems for most people.”
Deep in the lungs, fine particulate matter can penetrate the body’s defenses and even enter into the bloodstream.
In the short term, exposure to PM2.5 has been linked to increases in asthma attacks, hospital admissions for heart and lung conditions and premature death. Studies have connected long-term exposure to PM2.5 to heart and lung disease and even cancer.
A 2015 review by the International Agency for Research on Cancer concluded that fine particulate matter was a cause of lung cancer.
But particulate matter and ozone pollution from burning trees are just one piece of the puzzle with wildfire smoke.
As wildfires scorch communities across Southwest Colorado, they consume forests, but also buildings, vehicles and propane tanks, all of which give off toxic chemicals that can then be inhaled in wildfire smoke.
A 2021 study published in the peer-reviewed journal Nature Communications found that fine particulate matter from wildfires was up to 10 times more toxic than pollution from industrial sources.
Unlike pollution from cars or power plants, which is regulated, wildfires release whatever they burn.
“The particulates themselves can be made up of multiple chemicals and particles, which are basically poisons in the body,” El-Hasan said. “When something gets past the defenses of the lungs, you’re basically getting a dose of a carcinogen into your bloodstream thanks to the lungs.”
“It can be some pretty poisonous stuff that’s out there,” he said.
One 2012 study published in Environmental Health Perspectives estimated 339,000 people die annually across the globe because of exposure to wildfires.
Climate change has the potential to worsen the health effects of wildfires in Southwest Colorado, and it’s a point of concern for Devine.
“We think it’s very clear that this is one of several impacts on environmental public health that’s going to be exacerbated by global climate change,” he said. “We know that the western United States is going to be drier and we have a whole lot of forests that haven’t burned on their regular burn intervals and are drying out. The result of that is going to be hotter fires, bigger fires and more air quality impacts.”
Alongside more frequent and larger fires, scientists forecast more drought in the Southwest.
Drought will further the harmful effects of wildfires, not only by helping to ignite more blazes but also reducing rain, which cleanses the air, El-Hasan said.
As Southwest Colorado’s communities face worsening health risks from wildfires, they may also have an immediate solution that benefits both wildfire mitigation and residents’ health.
On June 8, the American Lung Association released a report that examined the potential for prescribed fires to mitigate the health impacts of wildfires.
Though research that directly contrasts the two is limited, the report concluded that emerging evidence suggests prescribed fires have fewer air quality and health impacts.
Prescribed fires often burn at lower intensities for less time than wildfires. Fire crews also plan burns to limit their effects on air quality, conduct them on days with higher humidity and under more predictable conditions.
Both reduce potential exposure to harmful wildfire smoke.
But the greatest benefit of prescribed burns is control. Crews can guide prescribed burns more readily, steering them away from things such as homes and propane tanks, and reducing the toxins that the fires release in smoke.
“Given the alternative of uncontrolled wildfires, certainly the preference would be to look more at prescribed burns as a tool to mitigate the negative air quality impacts (and) health impacts,” Torres said.
While the American Lung Association highlights the potential of prescribed fires, its report notes that scientists must conduct more research to compare the two and reach conclusions that can inform public health and land management.
As public health advocates and scientists begin studying the benefits of prescribed fire, there are steps that residents of Southwest Colorado can take to reduce their risk amid wildfires.
On days with heavy smoke, El-Hasan and Torres suggested people stay indoors and attempt close off their homes as best they can.
But precautions for wildfire smoke can also be more nuanced.
Wildfires typically follow a diurnal pattern with smoke sinking closer to the ground at night and rising as air mixes during the day. Air quality is often worst in early evening and at night and best around midday, Devine said.
“You can probably at certain air quality levels very safely go for a walk, but maybe not go for vigorous exercise,” he said. “Maybe you need to reduce your vigorous exercise rather than stop it entirely.”
Emerging research also suggests that for many people indoor air can be as bad since fine particulate matter from wildfire smoke can penetrate their homes.
“At certain air quality levels when we’re getting up into ‘very unhealthy’ and ‘hazardous,’ we’re starting to share messages in the public health community not just about staying indoors but actually trying to filter your air indoors,” Devine said.
Those concerned about the health impacts of smoke can always use N95 masks, though they must fit tightly to keep fine particulates out, he said.
With a fiery future forecast for Southwest Colorado, awareness and action will be key to addressing the health consequences of wildfires.
“We know that we can create very specific short-term spikes in unhealthy air because of wildfires, so we’re trying to focus on ways that the public can be better aware,” Torres said.